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[Liftoff] Add code comments on debug builds

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Code comments help a lot to understand the generated code. Add a
comment before each instruction, and some special comments for longer
instructions.

R=titzer@chromium.org

Bug: v8:6600
Change-Id: Ic18974e5cc89e23533e3abc54b0389723b77ff73
Reviewed-on: https://chromium-review.googlesource.com/1049626
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53064}
This commit is contained in:
Clemens Hammacher 2018-05-08 12:48:27 +02:00 committed by Commit Bot
parent c34562803e
commit 9f5018c9b0
1 changed files with 17 additions and 1 deletions
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18
src/wasm/baseline/liftoff-compiler.cc
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@ -43,6 +43,15 @@ namespace {
__ LoadFromInstance(dst.gp(), WASM_INSTANCE_OBJECT_OFFSET(name), \
LoadType(type).size());
#ifdef DEBUG
#define DEBUG_CODE_COMMENT(str) \
do { \
__ RecordComment(str); \
} while (false)
#else
#define DEBUG_CODE_COMMENT(str) ((void)0)
#endif
constexpr LoadType::LoadTypeValue kPointerLoadType =
kPointerSize == 8 ? LoadType::kI64Load : LoadType::kI32Load;
@ -493,8 +502,9 @@ class LiftoffCompiler {
BindUnboundLabels(decoder);
}
void NextInstruction(Decoder* decoder, WasmOpcode) {
void NextInstruction(Decoder* decoder, WasmOpcode opcode) {
TraceCacheState(decoder);
DEBUG_CODE_COMMENT(WasmOpcodes::OpcodeName(opcode));
}
void Block(Decoder* decoder, Control* block) {
@ -1473,6 +1483,7 @@ class LiftoffCompiler {
if (!FLAG_untrusted_code_mitigations || env_->use_trap_handler) {
return index;
}
DEBUG_CODE_COMMENT("Mask memory index");
// Make sure that we can overwrite {index}.
if (__ cache_state()->is_used(index)) {
LiftoffRegister old_index = index;
@ -1501,6 +1512,7 @@ class LiftoffCompiler {
}
uint32_t offset = imm.offset;
index = AddMemoryMasking(index, &offset, pinned);
DEBUG_CODE_COMMENT("Load from memory");
LiftoffRegister addr = pinned.set(__ GetUnusedRegister(kGpReg, pinned));
LOAD_INSTANCE_FIELD(addr, MemoryStart, kPointerLoadType);
RegClass rc = reg_class_for(value_type);
@ -1534,6 +1546,7 @@ class LiftoffCompiler {
}
uint32_t offset = imm.offset;
index = AddMemoryMasking(index, &offset, pinned);
DEBUG_CODE_COMMENT("Store to memory");
LiftoffRegister addr = pinned.set(__ GetUnusedRegister(kGpReg, pinned));
LOAD_INSTANCE_FIELD(addr, MemoryStart, kPointerLoadType);
uint32_t protected_store_pc = 0;
@ -1741,6 +1754,7 @@ class LiftoffCompiler {
__ emit_cond_jump(kUnsignedGreaterEqual, invalid_func_label, kWasmI32,
index.gp(), tmp_const.gp());
DEBUG_CODE_COMMENT("Check indirect call signature");
// Load the signature from {instance->ift_sig_ids[key]}
LOAD_INSTANCE_FIELD(table, IndirectFunctionTableSigIds, kPointerLoadType);
__ LoadConstant(tmp_const,
@ -1759,6 +1773,7 @@ class LiftoffCompiler {
LiftoffAssembler::kWasmIntPtr, scratch.gp(),
tmp_const.gp());
DEBUG_CODE_COMMENT("Execute indirect call");
if (kPointerSize == 8) {
// {index} has already been multiplied by 4. Multiply by another 2.
__ LoadConstant(tmp_const, WasmValue(2));
@ -1964,6 +1979,7 @@ void LiftoffCompilationUnit::AbortCompilation() {
#undef TRACE
#undef WASM_INSTANCE_OBJECT_OFFSET
#undef LOAD_INSTANCE_FIELD
#undef DEBUG_CODE_COMMENT
} // namespace wasm
} // namespace internal