Sriraman Tallam
17 years ago
24 changed files with 1332 additions and 131 deletions
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// icf.cc -- Identical Code Folding.
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//
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// Copyright 2009 Free Software Foundation, Inc.
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// Written by Sriraman Tallam <tmsriram@google.com>.
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// This file is part of gold.
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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// MA 02110-1301, USA.
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// Identical Code Folding Algorithm
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// ----------------------------------
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// Detecting identical functions is done here and the basic algorithm
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// is as follows. A checksum is computed on each .text section using
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// its contents and relocations. If the symbol name corresponding to
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// a relocation is known it is used to compute the checksum. If the
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// symbol name is not known the stringified name of the object and the
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// section number pointed to by the relocation is used. The checksums
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// are stored as keys in a hash map and a section is identical to some
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// other section if its checksum is already present in the hash map.
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// Checksum collisions are handled by using a multimap and explicitly
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// checking the contents when two sections have the same checksum.
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//
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// However, two functions A and B with identical text but with
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// relocations pointing to different .text sections can be identical if
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// the corresponding .text sections to which their relocations point to
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// turn out to be identical. Hence, this checksumming process must be
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// done repeatedly until convergence is obtained. Here is an example for
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// the following case :
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//
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// int funcA () int funcB ()
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// { {
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// return foo(); return goo();
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// } }
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//
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// The functions funcA and funcB are identical if functions foo() and
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// goo() are identical.
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//
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// Hence, as described above, we repeatedly do the checksumming,
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// assigning identical functions to the same group, until convergence is
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// obtained. Now, we have two different ways to do this depending on how
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// we initialize.
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//
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// Algorithm I :
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// -----------
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// We can start with marking all functions as different and repeatedly do
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// the checksumming. This has the advantage that we do not need to wait
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// for convergence. We can stop at any point and correctness will be
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// guaranteed although not all cases would have been found. However, this
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// has a problem that some cases can never be found even if it is run until
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// convergence. Here is an example with mutually recursive functions :
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//
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// int funcA (int a) int funcB (int a)
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// { {
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// if (a == 1) if (a == 1)
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// return 1; return 1;
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// return 1 + funcB(a - 1); return 1 + funcA(a - 1);
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// } }
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//
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// In this example funcA and funcB are identical and one of them could be
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// folded into the other. However, if we start with assuming that funcA
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// and funcB are not identical, the algorithm, even after it is run to
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// convergence, cannot detect that they are identical. It should be noted
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// that even if the functions were self-recursive, Algorithm I cannot catch
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// that they are identical, at least as is.
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//
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// Algorithm II :
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// ------------
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// Here we start with marking all functions as identical and then repeat
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// the checksumming until convergence. This can detect the above case
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// mentioned above. It can detect all cases that Algorithm I can and more.
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// However, the caveat is that it has to be run to convergence. It cannot
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// be stopped arbitrarily like Algorithm I as correctness cannot be
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// guaranteed. Algorithm II is not implemented.
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//
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// Algorithm I is used because experiments show that about three
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// iterations are more than enough to achieve convergence. Algorithm I can
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// handle recursive calls if it is changed to use a special common symbol
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// for recursive relocs. This seems to be the most common case that
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// Algorithm I could not catch as is. Mutually recursive calls are not
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// frequent and Algorithm I wins because of its ability to be stopped
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// arbitrarily.
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//
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// Caveat with using function pointers :
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// ------------------------------------
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//
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// Programs using function pointer comparisons/checks should use function
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// folding with caution as the result of such comparisons could be different
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// when folding takes place. This could lead to unexpected run-time
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// behaviour.
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//
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//
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// How to run : --icf
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// Optional parameters : --icf-iterations <num> --print-icf-sections
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//
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// Performance : Less than 20 % link-time overhead on industry strength
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// applications. Up to 6 % text size reductions.
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#include "gold.h" |
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#include "object.h" |
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#include "gc.h" |
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#include "icf.h" |
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#include "symtab.h" |
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#include "libiberty.h" |
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namespace gold |
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{ |
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// This function determines if a section or a group of identical
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// sections has unique contents. Such unique sections or groups can be
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// declared final and need not be processed any further.
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// Parameters :
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// ID_SECTION : Vector mapping a section index to a Section_id pair.
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// IS_SECN_OR_GROUP_UNIQUE : To check if a section or a group of identical
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// sections is already known to be unique.
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// SECTION_CONTENTS : Contains the section's text and relocs to sections
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// that cannot be folded. SECTION_CONTENTS are NULL
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// implies that this function is being called for the
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// first time before the first iteration of icf.
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static void |
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preprocess_for_unique_sections(const std::vector<Section_id>& id_section, |
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std::vector<bool>* is_secn_or_group_unique, |
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std::vector<std::string>* section_contents) |
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{ |
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Unordered_map<uint32_t, unsigned int> uniq_map; |
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std::pair<Unordered_map<uint32_t, unsigned int>::iterator, bool> |
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uniq_map_insert; |
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for (unsigned int i = 0; i < id_section.size(); i++) |
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{ |
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if ((*is_secn_or_group_unique)[i]) |
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continue; |
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uint32_t cksum; |
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Section_id secn = id_section[i]; |
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section_size_type plen; |
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if (section_contents == NULL) |
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{ |
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const unsigned char* contents; |
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contents = secn.first->section_contents(secn.second, |
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&plen, |
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false); |
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cksum = xcrc32(contents, plen, 0xffffffff); |
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} |
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else |
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{ |
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const unsigned char* contents_array = reinterpret_cast |
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<const unsigned char*>((*section_contents)[i].c_str()); |
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cksum = xcrc32(contents_array, (*section_contents)[i].length(), |
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0xffffffff); |
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} |
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uniq_map_insert = uniq_map.insert(std::make_pair(cksum, i)); |
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if (uniq_map_insert.second) |
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{ |
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(*is_secn_or_group_unique)[i] = true; |
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} |
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else |
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{ |
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(*is_secn_or_group_unique)[i] = false; |
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(*is_secn_or_group_unique)[uniq_map_insert.first->second] = false; |
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} |
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} |
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} |
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// This returns the buffer containing the section's contents, both
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// text and relocs. Relocs are differentiated as those pointing to
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// sections that could be folded and those that cannot. Only relocs
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// pointing to sections that could be folded are recomputed on
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// subsequent invocations of this function.
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// Parameters :
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// FIRST_ITERATION : true if it is the first invocation.
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// SECN : Section for which contents are desired.
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// SECTION_NUM : Unique section number of this section.
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// NUM_TRACKED_RELOCS : Vector reference to store the number of relocs
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// to ICF sections.
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// KEPT_SECTION_ID : Vector which maps folded sections to kept sections.
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// SECTION_CONTENTS : Store the section's text and relocs to non-ICF
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// sections.
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static std::string |
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get_section_contents(bool first_iteration, |
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const Section_id& secn, |
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unsigned int section_num, |
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unsigned int* num_tracked_relocs, |
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Symbol_table* symtab, |
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const std::vector<unsigned int>& kept_section_id, |
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std::vector<std::string>* section_contents) |
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{ |
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section_size_type plen; |
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const unsigned char* contents = NULL; |
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if (first_iteration) |
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{ |
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contents = secn.first->section_contents(secn.second, |
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&plen, |
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false); |
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} |
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// The buffer to hold all the contents including relocs. A checksum
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// is then computed on this buffer.
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std::string buffer; |
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std::string icf_reloc_buffer; |
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if (num_tracked_relocs) |
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*num_tracked_relocs = 0; |
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Icf::Section_list& seclist = symtab->icf()->section_reloc_list(); |
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Icf::Symbol_list& symlist = symtab->icf()->symbol_reloc_list(); |
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Icf::Addend_list& addendlist = symtab->icf()->addend_reloc_list(); |
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Icf::Section_list::iterator it_seclist = seclist.find(secn); |
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Icf::Symbol_list::iterator it_symlist = symlist.find(secn); |
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Icf::Addend_list::iterator it_addendlist = addendlist.find(secn); |
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buffer.clear(); |
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icf_reloc_buffer.clear(); |
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// Process relocs and put them into the buffer.
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if (it_seclist != seclist.end()) |
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{ |
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gold_assert(it_symlist != symlist.end()); |
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gold_assert(it_addendlist != addendlist.end()); |
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Icf::Sections_reachable_list v = it_seclist->second; |
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Icf::Symbol_info s = it_symlist->second; |
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Icf::Addend_info a = it_addendlist->second; |
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Icf::Sections_reachable_list::iterator it_v = v.begin(); |
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Icf::Symbol_info::iterator it_s = s.begin(); |
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Icf::Addend_info::iterator it_a = a.begin(); |
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for (; it_v != v.end(); ++it_v, ++it_s, ++it_a) |
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{ |
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// ADDEND_STR stores the symbol value and addend, each
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// atmost 16 hex digits long. it_v points to a pair
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// where first is the symbol value and second is the
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// addend.
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char addend_str[34]; |
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snprintf(addend_str, sizeof(addend_str), "%llx %llx", |
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(*it_a).first, (*it_a).second); |
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Section_id reloc_secn(it_v->first, it_v->second); |
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// If this reloc turns back and points to the same section,
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// like a recursive call, use a special symbol to mark this.
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if (reloc_secn.first == secn.first |
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&& reloc_secn.second == secn.second) |
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{ |
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if (first_iteration) |
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{ |
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buffer.append("R"); |
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buffer.append(addend_str); |
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buffer.append("@"); |
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} |
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continue; |
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} |
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Icf::Uniq_secn_id_map& section_id_map = |
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symtab->icf()->section_to_int_map(); |
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Icf::Uniq_secn_id_map::iterator section_id_map_it = |
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section_id_map.find(reloc_secn); |
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if (section_id_map_it != section_id_map.end()) |
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{ |
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// This is a reloc to a section that might be folded.
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if (num_tracked_relocs) |
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(*num_tracked_relocs)++; |
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char kept_section_str[10]; |
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unsigned int secn_id = section_id_map_it->second; |
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snprintf(kept_section_str, sizeof(kept_section_str), "%u", |
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kept_section_id[secn_id]); |
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if (first_iteration) |
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{ |
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buffer.append("ICF_R"); |
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buffer.append(addend_str); |
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} |
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icf_reloc_buffer.append(kept_section_str); |
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// Append the addend.
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icf_reloc_buffer.append(addend_str); |
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icf_reloc_buffer.append("@"); |
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} |
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else |
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{ |
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// This is a reloc to a section that cannot be folded.
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// Process it only in the first iteration.
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if (!first_iteration) |
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continue; |
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uint64_t secn_flags = (it_v->first)->section_flags(it_v->second); |
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// This reloc points to a merge section. Hash the
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// contents of this section.
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if ((secn_flags & elfcpp::SHF_MERGE) != 0) |
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{ |
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uint64_t entsize = |
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(it_v->first)->section_entsize(it_v->second); |
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long long offset = it_a->first + it_a->second; |
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section_size_type secn_len; |
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const unsigned char* str_contents = |
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(it_v->first)->section_contents(it_v->second, |
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&secn_len, |
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false) + offset; |
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if ((secn_flags & elfcpp::SHF_STRINGS) != 0) |
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{ |
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// String merge section.
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const char* str_char = |
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reinterpret_cast<const char*>(str_contents); |
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switch(entsize) |
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{ |
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case 1: |
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{ |
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buffer.append(str_char); |
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break; |
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} |
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case 2: |
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{ |
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const uint16_t* ptr_16 = |
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reinterpret_cast<const uint16_t*>(str_char); |
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unsigned int strlen_16 = 0; |
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// Find the NULL character.
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while(*(ptr_16 + strlen_16) != 0) |
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strlen_16++; |
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buffer.append(str_char, strlen_16 * 2); |
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} |
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break; |
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case 4: |
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{ |
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const uint32_t* ptr_32 = |
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reinterpret_cast<const uint32_t*>(str_char); |
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unsigned int strlen_32 = 0; |
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// Find the NULL character.
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while(*(ptr_32 + strlen_32) != 0) |
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strlen_32++; |
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buffer.append(str_char, strlen_32 * 4); |
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} |
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break; |
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default: |
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gold_unreachable(); |
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} |
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} |
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else |
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{ |
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// Use the entsize to determine the length.
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buffer.append(reinterpret_cast<const |
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char*>(str_contents), |
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entsize); |
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} |
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} |
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else if ((*it_s) != NULL) |
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{ |
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// If symbol name is available use that.
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const char *sym_name = (*it_s)->name(); |
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buffer.append(sym_name); |
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// Append the addend.
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buffer.append(addend_str); |
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buffer.append("@"); |
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} |
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else |
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{ |
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// Symbol name is not available, like for a local symbol,
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// use object and section id.
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buffer.append(it_v->first->name()); |
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char secn_id[10]; |
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snprintf(secn_id, sizeof(secn_id), "%u",it_v->second); |
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buffer.append(secn_id); |
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// Append the addend.
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buffer.append(addend_str); |
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buffer.append("@"); |
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} |
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} |
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} |
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} |
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if (first_iteration) |
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{ |
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buffer.append("Contents = "); |
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buffer.append(reinterpret_cast<const char*>(contents), plen); |
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// Store the section contents that dont change to avoid recomputing
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// during the next call to this function.
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(*section_contents)[section_num] = buffer; |
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} |
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else |
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{ |
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gold_assert(buffer.empty()); |
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// Reuse the contents computed in the previous iteration.
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buffer.append((*section_contents)[section_num]); |
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} |
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buffer.append(icf_reloc_buffer); |
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return buffer; |
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} |
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// This function computes a checksum on each section to detect and form
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// groups of identical sections. The first iteration does this for all
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// sections.
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// Further iterations do this only for the kept sections from each group to
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// determine if larger groups of identical sections could be formed. The
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// first section in each group is the kept section for that group.
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//
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// CRC32 is the checksumming algorithm and can have collisions. That is,
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// two sections with different contents can have the same checksum. Hence,
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// a multimap is used to maintain more than one group of checksum
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// identical sections. A section is added to a group only after its
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// contents are explicitly compared with the kept section of the group.
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//
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// Parameters :
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// ITERATION_NUM : Invocation instance of this function.
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// NUM_TRACKED_RELOCS : Vector reference to store the number of relocs
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// to ICF sections.
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// KEPT_SECTION_ID : Vector which maps folded sections to kept sections.
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// ID_SECTION : Vector mapping a section to an unique integer.
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// IS_SECN_OR_GROUP_UNIQUE : To check if a section or a group of identical
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// sectionsis already known to be unique.
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// SECTION_CONTENTS : Store the section's text and relocs to non-ICF
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// sections.
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static bool |
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match_sections(unsigned int iteration_num, |
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Symbol_table* symtab, |
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std::vector<unsigned int>* num_tracked_relocs, |
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std::vector<unsigned int>* kept_section_id, |
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const std::vector<Section_id>& id_section, |
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std::vector<bool>* is_secn_or_group_unique, |
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std::vector<std::string>* section_contents) |
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{ |
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Unordered_multimap<uint32_t, unsigned int> section_cksum; |
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std::pair<Unordered_multimap<uint32_t, unsigned int>::iterator, |
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Unordered_multimap<uint32_t, unsigned int>::iterator> key_range; |
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bool converged = true; |
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if (iteration_num == 1) |
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preprocess_for_unique_sections(id_section, |
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is_secn_or_group_unique, |
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NULL); |
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else |
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preprocess_for_unique_sections(id_section, |
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is_secn_or_group_unique, |
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section_contents); |
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std::vector<std::string> full_section_contents; |
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for (unsigned int i = 0; i < id_section.size(); i++) |
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{ |
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full_section_contents.push_back(""); |
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if ((*is_secn_or_group_unique)[i]) |
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continue; |
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Section_id secn = id_section[i]; |
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std::string this_secn_contents; |
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uint32_t cksum; |
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if (iteration_num == 1) |
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{ |
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unsigned int num_relocs = 0; |
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this_secn_contents = get_section_contents(true, secn, i, &num_relocs, |
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symtab, (*kept_section_id), |
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section_contents); |
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(*num_tracked_relocs)[i] = num_relocs; |
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} |
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else |
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{ |
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if ((*kept_section_id)[i] != i) |
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{ |
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// This section is already folded into something. See
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// if it should point to a different kept section.
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unsigned int kept_section = (*kept_section_id)[i]; |
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if (kept_section != (*kept_section_id)[kept_section]) |
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{ |
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(*kept_section_id)[i] = (*kept_section_id)[kept_section]; |
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} |
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continue; |
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} |
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this_secn_contents = get_section_contents(false, secn, i, NULL, |
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symtab, (*kept_section_id), |
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section_contents); |
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} |
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const unsigned char* this_secn_contents_array = |
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reinterpret_cast<const unsigned char*>(this_secn_contents.c_str()); |
|||
cksum = xcrc32(this_secn_contents_array, this_secn_contents.length(), |
|||
0xffffffff); |
|||
size_t count = section_cksum.count(cksum); |
|||
|
|||
if (count == 0) |
|||
{ |
|||
// Start a group with this cksum.
|
|||
section_cksum.insert(std::make_pair(cksum, i)); |
|||
full_section_contents[i] = this_secn_contents; |
|||
} |
|||
else |
|||
{ |
|||
key_range = section_cksum.equal_range(cksum); |
|||
Unordered_multimap<uint32_t, unsigned int>::iterator it; |
|||
// Search all the groups with this cksum for a match.
|
|||
for (it = key_range.first; it != key_range.second; ++it) |
|||
{ |
|||
unsigned int kept_section = it->second; |
|||
if (full_section_contents[kept_section].length() |
|||
!= this_secn_contents.length()) |
|||
continue; |
|||
if (memcmp(full_section_contents[kept_section].c_str(), |
|||
this_secn_contents.c_str(), |
|||
this_secn_contents.length()) != 0) |
|||
continue; |
|||
(*kept_section_id)[i] = kept_section; |
|||
converged = false; |
|||
break; |
|||
} |
|||
if (it == key_range.second) |
|||
{ |
|||
// Create a new group for this cksum.
|
|||
section_cksum.insert(std::make_pair(cksum, i)); |
|||
full_section_contents[i] = this_secn_contents; |
|||
} |
|||
} |
|||
// If there are no relocs to foldable sections do not process
|
|||
// this section any further.
|
|||
if (iteration_num == 1 && (*num_tracked_relocs)[i] == 0) |
|||
(*is_secn_or_group_unique)[i] = true; |
|||
} |
|||
|
|||
return converged; |
|||
} |
|||
|
|||
|
|||
// This is the main ICF function called in gold.cc. This does the
|
|||
// initialization and calls match_sections repeatedly (twice by default)
|
|||
// which computes the crc checksums and detects identical functions.
|
|||
|
|||
void |
|||
Icf::find_identical_sections(const Input_objects* input_objects, |
|||
Symbol_table* symtab) |
|||
{ |
|||
unsigned int section_num = 0; |
|||
std::vector<unsigned int> num_tracked_relocs; |
|||
std::vector<bool> is_secn_or_group_unique; |
|||
std::vector<std::string> section_contents; |
|||
|
|||
// Decide which sections are possible candidates first.
|
|||
|
|||
for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); |
|||
p != input_objects->relobj_end(); |
|||
++p) |
|||
{ |
|||
for (unsigned int i = 0;i < (*p)->shnum(); ++i) |
|||
{ |
|||
// Only looking to fold functions, so just look at .text sections.
|
|||
if (!is_prefix_of(".text.", (*p)->section_name(i).c_str())) |
|||
continue; |
|||
if (!(*p)->is_section_included(i)) |
|||
continue; |
|||
if (parameters->options().gc_sections() |
|||
&& symtab->gc()->is_section_garbage(*p, i)) |
|||
continue; |
|||
this->id_section_.push_back(Section_id(*p, i)); |
|||
this->section_id_[Section_id(*p, i)] = section_num; |
|||
this->kept_section_id_.push_back(section_num); |
|||
num_tracked_relocs.push_back(0); |
|||
is_secn_or_group_unique.push_back(false); |
|||
section_contents.push_back(""); |
|||
section_num++; |
|||
} |
|||
} |
|||
|
|||
unsigned int num_iterations = 0; |
|||
|
|||
// Default number of iterations to run ICF is 2.
|
|||
unsigned int max_iterations = (parameters->options().icf_iterations() > 0) |
|||
? parameters->options().icf_iterations() |
|||
: 2; |
|||
|
|||
bool converged = false; |
|||
|
|||
while (!converged && (num_iterations < max_iterations)) |
|||
{ |
|||
num_iterations++; |
|||
converged = match_sections(num_iterations, symtab, |
|||
&num_tracked_relocs, &this->kept_section_id_, |
|||
this->id_section_, &is_secn_or_group_unique, |
|||
§ion_contents); |
|||
} |
|||
|
|||
if (parameters->options().print_icf_sections()) |
|||
{ |
|||
if (converged) |
|||
gold_info(_("%s: ICF Converged after %u iteration(s)"), |
|||
program_name, num_iterations); |
|||
else |
|||
gold_info(_("%s: ICF stopped after %u iteration(s)"), |
|||
program_name, num_iterations); |
|||
} |
|||
|
|||
this->icf_ready(); |
|||
} |
|||
|
|||
// This function determines if the section corresponding to the
|
|||
// given object and index is folded based on if the kept section
|
|||
// is different from this section.
|
|||
|
|||
bool |
|||
Icf::is_section_folded(Object* obj, unsigned int shndx) |
|||
{ |
|||
Section_id secn(obj, shndx); |
|||
Uniq_secn_id_map::iterator it = this->section_id_.find(secn); |
|||
if (it == this->section_id_.end()) |
|||
return false; |
|||
unsigned int section_num = it->second; |
|||
unsigned int kept_section_id = this->kept_section_id_[section_num]; |
|||
return kept_section_id != section_num; |
|||
} |
|||
|
|||
// This function returns the folded section for the given section.
|
|||
|
|||
Section_id |
|||
Icf::get_folded_section(Object* dup_obj, unsigned int dup_shndx) |
|||
{ |
|||
Section_id dup_secn(dup_obj, dup_shndx); |
|||
Uniq_secn_id_map::iterator it = this->section_id_.find(dup_secn); |
|||
gold_assert(it != this->section_id_.end()); |
|||
unsigned int section_num = it->second; |
|||
unsigned int kept_section_id = this->kept_section_id_[section_num]; |
|||
Section_id folded_section = this->id_section_[kept_section_id]; |
|||
return folded_section; |
|||
} |
|||
|
|||
} // End of namespace gold.
|
|||
@ -0,0 +1,140 @@ |
|||
// icf.h -- Identical Code Folding
|
|||
|
|||
// Copyright 2009 Free Software Foundation, Inc.
|
|||
// Written by Sriraman Tallam <tmsriram@google.com>.
|
|||
|
|||
// This file is part of gold.
|
|||
|
|||
// This program is free software; you can redistribute it and/or modify
|
|||
// it under the terms of the GNU General Public License as published by
|
|||
// the Free Software Foundation; either version 3 of the License, or
|
|||
// (at your option) any later version.
|
|||
|
|||
// This program is distributed in the hope that it will be useful,
|
|||
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|||
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|||
// GNU General Public License for more details.
|
|||
|
|||
// You should have received a copy of the GNU General Public License
|
|||
// along with this program; if not, write to the Free Software
|
|||
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
|
|||
// MA 02110-1301, USA.
|
|||
|
|||
#ifndef GOLD_ICF_H |
|||
#define GOLD_ICF_H |
|||
|
|||
#include <vector> |
|||
|
|||
#include "elfcpp.h" |
|||
#include "symtab.h" |
|||
|
|||
namespace gold |
|||
{ |
|||
|
|||
class Object; |
|||
class Input_objects; |
|||
class Symbol_table; |
|||
|
|||
typedef std::pair<Object*, unsigned int> Section_id; |
|||
|
|||
class Icf |
|||
{ |
|||
public: |
|||
struct Section_id_hash |
|||
{ |
|||
size_t operator()(const Section_id& loc) const |
|||
{ return reinterpret_cast<uintptr_t>(loc.first) ^ loc.second; } |
|||
}; |
|||
|
|||
typedef std::vector<Section_id> Sections_reachable_list; |
|||
typedef std::vector<Symbol*> Symbol_info; |
|||
typedef std::vector<std::pair<long long, long long> > Addend_info; |
|||
typedef Unordered_map<Section_id, |
|||
Sections_reachable_list, |
|||
Section_id_hash> Section_list; |
|||
typedef Unordered_map<Section_id, Symbol_info, Section_id_hash> Symbol_list; |
|||
typedef Unordered_map<Section_id, Addend_info, Section_id_hash> Addend_list; |
|||
typedef Unordered_map<Section_id, |
|||
unsigned int, |
|||
Section_id_hash> Uniq_secn_id_map; |
|||
|
|||
Icf() |
|||
: id_section_(), section_id_(), kept_section_id_(), |
|||
num_tracked_relocs(NULL), icf_ready_(false), |
|||
section_reloc_list_(), symbol_reloc_list_(), |
|||
addend_reloc_list_() |
|||
{ } |
|||
|
|||
// Returns the kept folded identical section corresponding to
|
|||
// dup_obj and dup_shndx.
|
|||
Section_id |
|||
get_folded_section(Object* dup_obj, unsigned int dup_shndx); |
|||
|
|||
// Forms groups of identical sections where the first member
|
|||
// of each group is the kept section during folding.
|
|||
void |
|||
find_identical_sections(const Input_objects* input_objects, |
|||
Symbol_table* symtab); |
|||
|
|||
// This is set when ICF has been run and the groups of
|
|||
// identical sections have been formed.
|
|||
void |
|||
icf_ready() |
|||
{ this->icf_ready_ = true; } |
|||
|
|||
// Returns true if ICF has been run.
|
|||
bool |
|||
is_icf_ready() |
|||
{ return this->icf_ready_; } |
|||
|
|||
// Returns the kept section corresponding to the
|
|||
// given section.
|
|||
bool |
|||
is_section_folded(Object* obj, unsigned int shndx); |
|||
|
|||
// Returns a map of a section to a list of all sections referenced
|
|||
// by its relocations.
|
|||
Section_list& |
|||
section_reloc_list() |
|||
{ return this->section_reloc_list_; } |
|||
|
|||
// Returns a map of a section to a list of all symbols referenced
|
|||
// by its relocations.
|
|||
Symbol_list& |
|||
symbol_reloc_list() |
|||
{ return this->symbol_reloc_list_; } |
|||
|
|||
// Returns a maps of a section to a list of symbol values and addends
|
|||
// of its relocations.
|
|||
Addend_list& |
|||
addend_reloc_list() |
|||
{ return this->addend_reloc_list_; } |
|||
|
|||
// Returns a mapping of each section to a unique integer.
|
|||
Uniq_secn_id_map& |
|||
section_to_int_map() |
|||
{ return this->section_id_; } |
|||
|
|||
private: |
|||
|
|||
// Maps integers to sections.
|
|||
std::vector<Section_id> id_section_; |
|||
// Does the reverse.
|
|||
Uniq_secn_id_map section_id_; |
|||
// Given a section id, this maps it to the id of the kept
|
|||
// section. If the id's are the same then this section is
|
|||
// not folded.
|
|||
std::vector<unsigned int> kept_section_id_; |
|||
unsigned int* num_tracked_relocs; |
|||
// Flag to indicate if ICF has been run.
|
|||
bool icf_ready_; |
|||
|
|||
// These lists are populated by gc_process_relocs in gc.h.
|
|||
Section_list section_reloc_list_; |
|||
Symbol_list symbol_reloc_list_; |
|||
Addend_list addend_reloc_list_; |
|||
}; |
|||
|
|||
} // End of namespace gold.
|
|||
|
|||
#endif |
|||
@ -0,0 +1,51 @@ |
|||
// icf_test.cc -- a test case for gold
|
|||
|
|||
// Copyright 2009 Free Software Foundation, Inc.
|
|||
// Written by Sriraman Tallam <tmsriram@google.com>.
|
|||
|
|||
// This file is part of gold.
|
|||
|
|||
// This program is free software; you can redistribute it and/or modify
|
|||
// it under the terms of the GNU General Public License as published by
|
|||
// the Free Software Foundation; either version 3 of the License, or
|
|||
// (at your option) any later version.
|
|||
|
|||
// This program is distributed in the hope that it will be useful,
|
|||
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|||
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|||
// GNU General Public License for more details.
|
|||
|
|||
// You should have received a copy of the GNU General Public License
|
|||
// along with this program; if not, write to the Free Software
|
|||
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
|
|||
// MA 02110-1301, USA.
|
|||
|
|||
// The goal of this program is to verify if identical code folding
|
|||
// correctly identifies and folds functions. folded_func must be
|
|||
// folded into kept_func.
|
|||
|
|||
int common() |
|||
{ |
|||
return 1; |
|||
} |
|||
|
|||
int kept_func() |
|||
{ |
|||
common(); |
|||
// Recursive call.
|
|||
kept_func(); |
|||
return 1; |
|||
} |
|||
|
|||
int folded_func() |
|||
{ |
|||
common(); |
|||
// Recursive call.
|
|||
folded_func(); |
|||
return 1; |
|||
} |
|||
|
|||
int main() |
|||
{ |
|||
return 0; |
|||
} |
|||
@ -0,0 +1,40 @@ |
|||
#!/bin/sh |
|||
|
|||
# icf_test.sh -- test --icf |
|||
|
|||
# Copyright 2009 Free Software Foundation, Inc. |
|||
# Written by Sriraman Tallam <tmsriram@google.com>. |
|||
|
|||
# This file is part of gold. |
|||
|
|||
# This program is free software; you can redistribute it and/or modify |
|||
# it under the terms of the GNU General Public License as published by |
|||
# the Free Software Foundation; either version 3 of the License, or |
|||
# (at your option) any later version. |
|||
|
|||
# This program is distributed in the hope that it will be useful, |
|||
# but WITHOUT ANY WARRANTY; without even the implied warranty of |
|||
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
|||
# GNU General Public License for more details. |
|||
|
|||
# You should have received a copy of the GNU General Public License |
|||
# along with this program; if not, write to the Free Software |
|||
# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
|||
# MA 02110-1301, USA. |
|||
|
|||
# The goal of this program is to verify if icf works as expected. |
|||
# File icf_test.cc is in this test. This program checks if the |
|||
# identical sections are correctly folded. |
|||
|
|||
check() |
|||
{ |
|||
func_addr_1=`grep $2 $1 | awk '{print $1}'` |
|||
func_addr_2=`grep $3 $1 | awk '{print $1}'` |
|||
if [ $func_addr_1 != $func_addr_2 ] |
|||
then |
|||
echo "Identical Code Folding failed to fold" $2 "and" $3 |
|||
exit 1 |
|||
fi |
|||
} |
|||
|
|||
check icf_test.stdout "folded_func" "kept_func" |
|||
Loading…
Reference in new issue