[llvm] 4f39139 - [llvm-mc] Add --runs option for benchmarking (#151149)
via llvm-commits
llvm-commits at lists.llvm.org
Wed Jul 30 09:05:49 PDT 2025
Author: Rahul Joshi
Date: 2025-07-30T09:05:46-07:00
New Revision: 4f39139df31bd908ce0253aa8078f509aa0327d0
URL: https://github.com/llvm/llvm-project/commit/4f39139df31bd908ce0253aa8078f509aa0327d0
DIFF: https://github.com/llvm/llvm-project/commit/4f39139df31bd908ce0253aa8078f509aa0327d0.diff
LOG: [llvm-mc] Add --runs option for benchmarking (#151149)
Add support for measuring decode times in llvm-mc tool. Add command line
options to enable time-trace profiling (similar to llc or opt) and add
option `runs` to run the decoder several times on each instruction.
Added:
llvm/test/tools/llvm-mc/disassembler-profile.test
Modified:
llvm/tools/llvm-mc/Disassembler.cpp
llvm/tools/llvm-mc/Disassembler.h
llvm/tools/llvm-mc/llvm-mc.cpp
Removed:
################################################################################
diff --git a/llvm/test/tools/llvm-mc/disassembler-profile.test b/llvm/test/tools/llvm-mc/disassembler-profile.test
new file mode 100644
index 0000000000000..67afdce3a5423
--- /dev/null
+++ b/llvm/test/tools/llvm-mc/disassembler-profile.test
@@ -0,0 +1,12 @@
+# REQUIRES: aarch64-registered-target
+# RUN: rm -rf %t.json
+# RUN: llvm-mc -triple=aarch64 -disassemble -o /dev/null %s -runs=1000 -time-trace -time-trace-file=%t.json
+# RUN: FileCheck --input-file %t.json %s
+
+# Note: Test input taken from llvm/test/MC/Disassembler/AArch64/udf.txt
+
+# CHECK: "name":"Total getInstruction"
+# CHECK: "args":{"count":3,"avg ms":{{.*}}}
+[0x00,0x00,0x00,0x00]
+[0x01,0x02,0x00,0x00]
+[0xff,0xff,0x00,0x00]
diff --git a/llvm/tools/llvm-mc/Disassembler.cpp b/llvm/tools/llvm-mc/Disassembler.cpp
index 86727931067a5..2ee422126dbfb 100644
--- a/llvm/tools/llvm-mc/Disassembler.cpp
+++ b/llvm/tools/llvm-mc/Disassembler.cpp
@@ -24,6 +24,7 @@
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/SourceMgr.h"
+#include "llvm/Support/TimeProfiler.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/TargetParser/Triple.h"
@@ -32,24 +33,29 @@ using namespace llvm;
typedef std::pair<std::vector<unsigned char>, std::vector<const char *>>
ByteArrayTy;
-static bool PrintInsts(const MCDisassembler &DisAsm, const ByteArrayTy &Bytes,
+static MCDisassembler::DecodeStatus getInstruction(const MCDisassembler &DisAsm,
+ const MCSubtargetInfo &STI,
+ MCInst &Inst, uint64_t &Size,
+ ArrayRef<uint8_t> Bytes,
+ uint64_t Address) {
+ if (STI.getTargetTriple().getArch() == Triple::hexagon)
+ return DisAsm.getInstructionBundle(Inst, Size, Bytes, Address, nulls());
+ return DisAsm.getInstruction(Inst, Size, Bytes, Address, nulls());
+}
+
+static bool printInsts(const MCDisassembler &DisAsm, const ByteArrayTy &Bytes,
SourceMgr &SM, MCStreamer &Streamer, bool InAtomicBlock,
- const MCSubtargetInfo &STI) {
+ const MCSubtargetInfo &STI, unsigned NumBenchmarkRuns) {
ArrayRef<uint8_t> Data(Bytes.first);
// Disassemble it to strings.
uint64_t Size;
- uint64_t Index;
- for (Index = 0; Index < Bytes.first.size(); Index += Size) {
- MCInst Inst;
+ for (uint64_t Index = 0; Index < Bytes.first.size(); Index += Size) {
- MCDisassembler::DecodeStatus S;
- if (STI.getTargetTriple().getArch() == Triple::hexagon)
- S = DisAsm.getInstructionBundle(Inst, Size, Data.slice(Index), Index,
- nulls());
- else
- S = DisAsm.getInstruction(Inst, Size, Data.slice(Index), Index, nulls());
+ MCInst Inst;
+ MCDisassembler::DecodeStatus S =
+ getInstruction(DisAsm, STI, Inst, Size, Data.slice(Index), Index);
switch (S) {
case MCDisassembler::Fail:
SM.PrintMessage(SMLoc::getFromPointer(Bytes.second[Index]),
@@ -74,6 +80,18 @@ static bool PrintInsts(const MCDisassembler &DisAsm, const ByteArrayTy &Bytes,
Streamer.emitInstruction(Inst, STI);
break;
}
+
+ if (S == MCDisassembler::Success && NumBenchmarkRuns != 0) {
+ // Benchmark mode, collect timing for decoding the instruction several
+ // times.
+ MCInst BMInst;
+ TimeTraceScope timeScope("getInstruction");
+ for (unsigned I = 0; I < NumBenchmarkRuns; ++I) {
+ BMInst.clear();
+ BMInst.setOpcode(0);
+ S = getInstruction(DisAsm, STI, BMInst, Size, Data.slice(Index), Index);
+ }
+ }
}
return false;
@@ -151,7 +169,7 @@ int Disassembler::disassemble(const Target &T, const std::string &Triple,
MCSubtargetInfo &STI, MCStreamer &Streamer,
MemoryBuffer &Buffer, SourceMgr &SM,
MCContext &Ctx, const MCTargetOptions &MCOptions,
- bool HexBytes) {
+ bool HexBytes, unsigned NumBenchmarkRuns) {
std::unique_ptr<const MCRegisterInfo> MRI(T.createMCRegInfo(Triple));
if (!MRI) {
errs() << "error: no register info for target " << Triple << "\n";
@@ -207,8 +225,8 @@ int Disassembler::disassemble(const Target &T, const std::string &Triple,
ErrorOccurred |= byteArrayFromString(ByteArray, Str, SM, HexBytes);
if (!ByteArray.first.empty())
- ErrorOccurred |=
- PrintInsts(*DisAsm, ByteArray, SM, Streamer, InAtomicBlock, STI);
+ ErrorOccurred |= printInsts(*DisAsm, ByteArray, SM, Streamer,
+ InAtomicBlock, STI, NumBenchmarkRuns);
}
if (InAtomicBlock) {
diff --git a/llvm/tools/llvm-mc/Disassembler.h b/llvm/tools/llvm-mc/Disassembler.h
index 5efffca1e9926..5ee47d54200be 100644
--- a/llvm/tools/llvm-mc/Disassembler.h
+++ b/llvm/tools/llvm-mc/Disassembler.h
@@ -32,7 +32,8 @@ class Disassembler {
static int disassemble(const Target &T, const std::string &Triple,
MCSubtargetInfo &STI, MCStreamer &Streamer,
MemoryBuffer &Buffer, SourceMgr &SM, MCContext &Ctx,
- const MCTargetOptions &MCOptions, bool HexBytes);
+ const MCTargetOptions &MCOptions, bool HexBytes,
+ unsigned NumBenchmarkRuns);
};
} // namespace llvm
diff --git a/llvm/tools/llvm-mc/llvm-mc.cpp b/llvm/tools/llvm-mc/llvm-mc.cpp
index da89af71bbbe8..f69f7c725c6b4 100644
--- a/llvm/tools/llvm-mc/llvm-mc.cpp
+++ b/llvm/tools/llvm-mc/llvm-mc.cpp
@@ -12,6 +12,7 @@
//===----------------------------------------------------------------------===//
#include "Disassembler.h"
+#include "llvm/ADT/ScopeExit.h"
#include "llvm/DWARFCFIChecker/DWARFCFIFunctionFrameAnalyzer.h"
#include "llvm/DWARFCFIChecker/DWARFCFIFunctionFrameStreamer.h"
#include "llvm/MC/MCAsmBackend.h"
@@ -37,6 +38,7 @@
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/TargetSelect.h"
+#include "llvm/Support/TimeProfiler.h"
#include "llvm/Support/ToolOutputFile.h"
#include "llvm/Support/WithColor.h"
#include "llvm/TargetParser/Host.h"
@@ -240,6 +242,23 @@ static cl::opt<ActionType> Action(
"Colored disassembly of strings of hex bytes")),
cl::cat(MCCategory));
+static cl::opt<unsigned>
+ NumBenchmarkRuns("runs", cl::desc("Number of runs for benchmarking"),
+ cl::cat(MCCategory));
+
+static cl::opt<bool> TimeTrace("time-trace", cl::desc("Record time trace"));
+
+static cl::opt<unsigned> TimeTraceGranularity(
+ "time-trace-granularity",
+ cl::desc(
+ "Minimum time granularity (in microseconds) traced by time profiler"),
+ cl::init(500), cl::Hidden);
+
+static cl::opt<std::string>
+ TimeTraceFile("time-trace-file",
+ cl::desc("Specify time trace file destination"),
+ cl::value_desc("filename"));
+
static const Target *GetTarget(const char *ProgName) {
// Figure out the target triple.
if (TripleName.empty())
@@ -371,6 +390,20 @@ int main(int argc, char **argv) {
cl::HideUnrelatedOptions({&MCCategory, &getColorCategory()});
cl::ParseCommandLineOptions(argc, argv, "llvm machine code playground\n");
+
+ if (TimeTrace)
+ timeTraceProfilerInitialize(TimeTraceGranularity, argv[0]);
+
+ auto TimeTraceScopeExit = make_scope_exit([]() {
+ if (!TimeTrace)
+ return;
+ if (auto E = timeTraceProfilerWrite(TimeTraceFile, OutputFilename)) {
+ logAllUnhandledErrors(std::move(E), errs());
+ return;
+ }
+ timeTraceProfilerCleanup();
+ });
+
MCTargetOptions MCOptions = mc::InitMCTargetOptionsFromFlags();
MCOptions.CompressDebugSections = CompressDebugSections.getValue();
MCOptions.ShowMCInst = ShowInst;
@@ -620,7 +653,8 @@ int main(int argc, char **argv) {
}
if (disassemble)
Res = Disassembler::disassemble(*TheTarget, TripleName, *STI, *Str, *Buffer,
- SrcMgr, Ctx, MCOptions, HexBytes);
+ SrcMgr, Ctx, MCOptions, HexBytes,
+ NumBenchmarkRuns);
// Keep output if no errors.
if (Res == 0) {
@@ -628,5 +662,6 @@ int main(int argc, char **argv) {
if (DwoOut)
DwoOut->keep();
}
+
return Res;
}
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