From a5f6dda2bc0e6f38728037237cde2f548605bf7b Mon Sep 17 00:00:00 2001
From: Andrew Waterman <andrew@sifive.com>
Date: Wed, 16 Apr 2025 15:28:09 -0700
Subject: [PATCH] Remove VLAs in DTM (-Wvla)

---
 fesvr/dtm.cc | 28 +++++++++++++---------------
 fesvr/dtm.h  |  2 --
 2 files changed, 13 insertions(+), 17 deletions(-)

diff --git a/fesvr/dtm.cc b/fesvr/dtm.cc
index ffbb9e4c..a0c3254d 100644
--- a/fesvr/dtm.cc
+++ b/fesvr/dtm.cc
@@ -51,6 +51,9 @@
     }                                                           \
   }
 
+#define MAX_DATA_WORDS (1 << DM_ABSTRACTCS_DATACOUNT_LENGTH)
+#define MAX_PROG_WORDS (1 << DM_ABSTRACTCS_PROGBUFSIZE_LENGTH)
+
 uint32_t dtm_t::do_command(dtm_t::req r)
 {
   req_buf = r;
@@ -145,7 +148,7 @@ void dtm_t::resume(int hartsel)
 
 uint64_t dtm_t::save_reg(unsigned regno)
 {
-  uint32_t data[xlen/(8*4)];
+  uint32_t data[MAX_DATA_WORDS];
   uint32_t command = AC_ACCESS_REGISTER_TRANSFER | AC_AR_SIZE(xlen) | AC_AR_REGNO(regno);
   RUN_AC_OR_DIE(command, 0, 0, data, xlen / (8*4));
 
@@ -158,7 +161,7 @@ uint64_t dtm_t::save_reg(unsigned regno)
 
 void dtm_t::restore_reg(unsigned regno, uint64_t val)
 {
-  uint32_t data[xlen/(8*4)];
+  uint32_t data[MAX_DATA_WORDS];
   data[0] = (uint32_t) val;
   if (xlen > 32) {
     data[1] = (uint32_t) (val >> 32);
@@ -177,8 +180,8 @@ uint32_t dtm_t::run_abstract_command(uint32_t command,
                                      const uint32_t program[], size_t program_n,
                                      uint32_t data[], size_t data_n)
 { 
-  assert(program_n <= ram_words);
-  assert(data_n    <= data_words);
+  assert(program_n <= MAX_PROG_WORDS);
+  assert(data_n    <= MAX_DATA_WORDS);
   
   for (size_t i = 0; i < program_n; i++) {
     write(DM_PROGBUF0 + i, program[i]);
@@ -217,8 +220,8 @@ size_t dtm_t::chunk_align()
 
 void dtm_t::read_chunk(uint64_t taddr, size_t len, void* dst)
 {
-  uint32_t prog[ram_words];
-  uint32_t data[data_words];
+  uint32_t prog[MAX_PROG_WORDS];
+  uint32_t data[MAX_DATA_WORDS];
 
   uint8_t * curr = (uint8_t*) dst;
 
@@ -270,8 +273,8 @@ void dtm_t::read_chunk(uint64_t taddr, size_t len, void* dst)
 
 void dtm_t::write_chunk(uint64_t taddr, size_t len, const void* src)
 {  
-  uint32_t prog[ram_words];
-  uint32_t data[data_words];
+  uint32_t prog[MAX_PROG_WORDS];
+  uint32_t data[MAX_DATA_WORDS];
 
   const uint8_t * curr = (const uint8_t*) src;
 
@@ -365,8 +368,8 @@ void dtm_t::die(uint32_t cmderr)
 
 void dtm_t::clear_chunk(uint64_t taddr, size_t len)
 {
-  uint32_t prog[ram_words];
-  uint32_t data[data_words];
+  uint32_t prog[MAX_PROG_WORDS];
+  uint32_t data[MAX_DATA_WORDS];
   
   halt(current_hart);
   uint64_t s0 = save_reg(S0);
@@ -563,11 +566,6 @@ void dtm_t::producer_thread()
   // Poll until the debugger agrees it's enabled.
   while ((read(DM_DMCONTROL) & DM_DMCONTROL_DMACTIVE) == 0) ;
     
-  // These are checked every time we run an abstract command.
-  uint32_t abstractcs = read(DM_ABSTRACTCS);
-  ram_words = get_field(abstractcs, DM_ABSTRACTCS_PROGBUFSIZE);
-  data_words = get_field(abstractcs, DM_ABSTRACTCS_DATACOUNT);
-
   // These things are only needed for the 'modify_csr' function.
   // That could be re-written to not use these at some performance
   // overhead.
diff --git a/fesvr/dtm.h b/fesvr/dtm.h
index f47b648c..03c2f793 100644
--- a/fesvr/dtm.h
+++ b/fesvr/dtm.h
@@ -109,8 +109,6 @@ class dtm_t : public htif_t
 
   static const int max_idle_cycles = 10000;
 
-  size_t ram_words;
-  size_t data_words;
   int num_harts;
   int current_hart;