Don't compress empty debug section

2012-07-03  H.J. Lu  <hongjiu.lu@intel.com>

	PR binutils/14319
	* elf.c (_bfd_elf_make_section_from_shdr): Don't compress empty
	debug section.

2012-07-03  H.J. Lu  <hongjiu.lu@intel.com>

	PR binutils/14319
	* binutils-all/compress.exp: Test compress empty debug sections.

	* binutils-all/dw2-empty.S: New file.

bfd/ChangeLog

@@ -1,3 +1,9 @@
+2012-07-03  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR binutils/14319
+	* elf.c (_bfd_elf_make_section_from_shdr): Don't compress empty
+	debug section.
+
 2012-07-03  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR ld/3351

bfd/elf.c

@@ -1025,7 +1025,7 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
       else
 	{
 	  /* Normal section.  Check if we should compress.  */
-	  if ((abfd->flags & BFD_COMPRESS))
+	  if ((abfd->flags & BFD_COMPRESS) && newsect->size != 0)
 	    action = compress;
 	}
 

binutils/testsuite/ChangeLog

@@ -1,3 +1,10 @@
+2012-07-03  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR binutils/14319
+	* binutils-all/compress.exp: Test compress empty debug sections.
+
+	* binutils-all/dw2-empty.S: New file.
+
 2012-06-07  Thomas Schwinge  <thomas@codesourcery.com>
 
 	* binutils-all/i386/i386.exp: Don't skip for x86_64-*-linux*.

binutils/testsuite/binutils-all/compress.exp

@@ -133,3 +133,32 @@ if ![string match "" $got] then {
 	pass "$testname"
     }
 }
+
+set testfile tmpdir/dw2-emty.o
+
+if { ![binutils_assemble_flags $srcdir/$subdir/dw2-empty.S $testfile --nocompress-debug-sections] } then {
+    unsupported "compressed debug sections"
+    return
+}
+
+set testname "objcopy compress empty debug sections"
+set got [binutils_run $OBJCOPY "--compress-debug-sections $testfile ${copyfile}.o"]
+if ![string match "" $got] then {
+    fail "objcopy ($testname)"
+} else {
+    send_log "cmp $testfile ${copyfile}.o\n"
+    verbose "cmp $testfile ${copyfile}.o"
+    set src1 ${testfile}
+    set src2 ${copyfile}.o
+    set status [remote_exec build cmp "${src1} ${src2}"]
+    set exec_output [lindex $status 1]
+    set exec_output [prune_warnings $exec_output]
+
+    if [string match "" $exec_output] then {
+	pass "objcopy ($testname)"
+    } else {
+	send_log "$exec_output\n"
+	verbose "$exec_output" 1
+	fail "objcopy ($testname)"
+    }
+}

binutils/testsuite/binutils-all/dw2-empty.S

@@ -0,0 +1 @@
+	.section .debug_line