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Implement AOT static PGO (#2243)

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LLVM PGO (Profile-Guided Optimization) allows the compiler to better optimize code
for how it actually runs. This PR implements the AOT static PGO, and is tested on
Linux x86-64 and x86-32. The basic steps are:

1. Use `wamrc --enable-llvm-pgo -o <aot_file_of_pgo> <wasm_file>`
   to generate an instrumented aot file.
2. Compile iwasm with `cmake -DWAMR_BUILD_STATIC_PGO=1` and run
      `iwasm --gen-prof-file=<raw_profile_file> <aot_file_of_pgo>`
    to generate the raw profile file.
3. Run `llvm-profdata merge -output=<profile_file> <raw_profile_file>`
    to merge the raw profile file into the profile file.
4. Run `wamrc --use-prof-file=<profile_file> -o <aot_file> <wasm_file>`
    to generate the optimized aot file.
5. Run the optimized aot_file: `iwasm <aot_file>`.

The test scripts are also added for each benchmark, run `test_pgo.sh` under
each benchmark's folder to test the AOT static pgo.
This commit is contained in:
Wenyong Huang
2023-06-05 09:17:39 +08:00
committed by GitHub
parent f1e9029ebc
commit 8d88471c46
29 changed files with 2000 additions and 53 deletions
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26
core/iwasm/compilation/aot_llvm.c
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@ -1670,6 +1670,12 @@ aot_create_comp_context(const AOTCompData *comp_data, aot_comp_option_t option)
if (option->disable_llvm_lto)
comp_ctx->disable_llvm_lto = true;
if (option->enable_llvm_pgo)
comp_ctx->enable_llvm_pgo = true;
if (option->use_prof_file)
comp_ctx->use_prof_file = option->use_prof_file;
if (option->enable_stack_estimation)
comp_ctx->enable_stack_estimation = true;
@ -2829,3 +2835,23 @@ aot_load_const_from_table(AOTCompContext *comp_ctx, LLVMValueRef base,
(void)const_type;
return const_value;
}
bool
aot_set_cond_br_weights(AOTCompContext *comp_ctx, LLVMValueRef cond_br,
int32 weights_true, int32 weights_false)
{
LLVMMetadataRef md_nodes[3], meta_data;
LLVMValueRef meta_data_as_value;
md_nodes[0] = LLVMMDStringInContext2(comp_ctx->context, "branch_weights",
strlen("branch_weights"));
md_nodes[1] = LLVMValueAsMetadata(I32_CONST(weights_true));
md_nodes[2] = LLVMValueAsMetadata(I32_CONST(weights_false));
meta_data = LLVMMDNodeInContext2(comp_ctx->context, md_nodes, 3);
meta_data_as_value = LLVMMetadataAsValue(comp_ctx->context, meta_data);
LLVMSetMetadata(cond_br, 2, meta_data_as_value);
return true;
}