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[MCA] Use MCInstrAnalysis to analyse call/return instructions #123882

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merged 2 commits into from
Jan 22, 2025
Merged

[MCA] Use MCInstrAnalysis to analyse call/return instructions #123882

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6ac9962
[MCA] Use MCInstrAnalysis to analyse call/return instructions
wangpc-pp Jan 22, 2025
e0f9ac8
Register MCInstrAnalysis for SystemZ to fix test errors
wangpc-pp Jan 22, 2025
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16 changes: 8 additions & 8 deletions llvm/lib/MCA/InstrBuilder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -219,11 +219,10 @@ static void initializeUsedResources(InstrDesc &ID,
});
}

static void computeMaxLatency(InstrDesc &ID, const MCInstrDesc &MCDesc,
const MCSchedClassDesc &SCDesc,
const MCSubtargetInfo &STI,
unsigned CallLatency) {
if (MCDesc.isCall()) {
static void computeMaxLatency(InstrDesc &ID, const MCSchedClassDesc &SCDesc,
const MCSubtargetInfo &STI, unsigned CallLatency,
bool IsCall) {
if (IsCall) {
// We cannot estimate how long this call will take.
// Artificially set an arbitrarily high latency.
ID.MaxLatency = CallLatency;
Expand Down Expand Up @@ -599,23 +598,24 @@ InstrBuilder::createInstrDescImpl(const MCInst &MCI,
ID->NumMicroOps = SCDesc.NumMicroOps;
ID->SchedClassID = SchedClassID;

if (MCDesc.isCall() && FirstCallInst) {
bool IsCall = MCIA->isCall(MCI);
if (IsCall && FirstCallInst) {
// We don't correctly model calls.
WithColor::warning() << "found a call in the input assembly sequence.\n";
WithColor::note() << "call instructions are not correctly modeled. "
<< "Assume a latency of " << CallLatency << "cy.\n";
FirstCallInst = false;
}

if (MCDesc.isReturn() && FirstReturnInst) {
if (MCIA->isReturn(MCI) && FirstReturnInst) {
WithColor::warning() << "found a return instruction in the input"
<< " assembly sequence.\n";
WithColor::note() << "program counter updates are ignored.\n";
FirstReturnInst = false;
}

initializeUsedResources(*ID, SCDesc, STI, ProcResourceMasks);
computeMaxLatency(*ID, MCDesc, SCDesc, STI, CallLatency);
computeMaxLatency(*ID, SCDesc, STI, CallLatency, IsCall);

if (Error Err = verifyOperands(MCDesc, MCI))
return std::move(Err);
Expand Down
9 changes: 9 additions & 0 deletions llvm/lib/Target/SystemZ/MCTargetDesc/SystemZMCTargetDesc.cpp
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Expand Up @@ -15,6 +15,7 @@
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstrAnalysis.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCStreamer.h"
Expand Down Expand Up @@ -243,6 +244,10 @@ createNullTargetStreamer(MCStreamer &S) {
return new SystemZTargetStreamer(S);
}

static MCInstrAnalysis *createSystemZMCInstrAnalysis(const MCInstrInfo *Info) {
return new MCInstrAnalysis(Info);
}

extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeSystemZTargetMC() {
// Register the MCAsmInfo.
TargetRegistry::RegisterMCAsmInfo(getTheSystemZTarget(),
Expand Down Expand Up @@ -283,4 +288,8 @@ extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeSystemZTargetMC() {
// Register the null streamer
TargetRegistry::RegisterNullTargetStreamer(getTheSystemZTarget(),
createNullTargetStreamer);

// Register the MCInstrAnalysis.
TargetRegistry::RegisterMCInstrAnalysis(getTheSystemZTarget(),
createSystemZMCInstrAnalysis);
}
15 changes: 6 additions & 9 deletions llvm/test/tools/llvm-mca/RISCV/SiFive7/jump.s
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Expand Up @@ -12,12 +12,12 @@ ret

# CHECK: Iterations: 1
# CHECK-NEXT: Instructions: 5
# CHECK-NEXT: Total Cycles: 10
# CHECK-NEXT: Total Cycles: 200
# CHECK-NEXT: Total uOps: 5

# CHECK: Dispatch Width: 2
# CHECK-NEXT: uOps Per Cycle: 0.50
# CHECK-NEXT: IPC: 0.50
# CHECK-NEXT: uOps Per Cycle: 0.03
# CHECK-NEXT: IPC: 0.03
# CHECK-NEXT: Block RThroughput: 5.0

# CHECK: Instruction Info:
Expand Down Expand Up @@ -58,13 +58,10 @@ ret
# CHECK-NEXT: - - - 1.00 - - - - ret

# CHECK: Timeline view:
# CHECK-NEXT: Index 0123456789
# CHECK-NEXT: Index 0123

# CHECK: [0,0] DeeE . . j .Ltmp0
# CHECK-NEXT: [0,1] .DeeE. . jal a0, .Ltmp1
# CHECK-NEXT: [0,2] . DeeE . jr a0
# CHECK-NEXT: [0,3] . DeeE. jalr t0, a0
# CHECK-NEXT: [0,4] . .DeeE ret
# CHECK: [0,0] DeeE j .Ltmp0
# CHECK-NEXT: Truncated display due to cycle limit

# CHECK: Average Wait times (based on the timeline view):
# CHECK-NEXT: [0]: Executions
Expand Down
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