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[llvm-exegesis] Add explicit support for setting DF in X86 #115644

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Merged
merged 1 commit into from
Nov 18, 2024
Merged

[llvm-exegesis] Add explicit support for setting DF in X86 #115644

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13 changes: 13 additions & 0 deletions llvm/tools/llvm-exegesis/lib/X86/Target.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -537,6 +537,8 @@ struct ConstantInliner {
std::vector<MCInst> loadImplicitRegAndFinalize(unsigned Opcode,
unsigned Value);

std::vector<MCInst> loadDirectionFlagAndFinalize();

private:
ConstantInliner &add(const MCInst &Inst) {
Instructions.push_back(Inst);
Expand Down Expand Up @@ -612,6 +614,15 @@ ConstantInliner::loadImplicitRegAndFinalize(unsigned Opcode, unsigned Value) {
return std::move(Instructions);
}

std::vector<MCInst> ConstantInliner::loadDirectionFlagAndFinalize() {
if (Constant_.isZero())
add(MCInstBuilder(X86::CLD));
else if (Constant_.isOne())
add(MCInstBuilder(X86::STD));

return std::move(Instructions);
}

void ConstantInliner::initStack(unsigned Bytes) {
assert(Constant_.getBitWidth() <= Bytes * 8 &&
"Value does not have the correct size");
Expand Down Expand Up @@ -1089,6 +1100,8 @@ std::vector<MCInst> ExegesisX86Target::setRegTo(const MCSubtargetInfo &STI,
0x1f80);
if (Reg == X86::FPCW)
return CI.loadImplicitRegAndFinalize(X86::FLDCW16m, 0x37f);
if (Reg == X86::DF)
return CI.loadDirectionFlagAndFinalize();
return {}; // Not yet implemented.
}

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8 changes: 8 additions & 0 deletions llvm/unittests/tools/llvm-exegesis/X86/TargetTest.cpp
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Expand Up @@ -585,6 +585,14 @@ TEST_F(X86Core2TargetTest, SetRegToFP1_4Bits) {
OpcodeIs(X86::LD_Fp80m), IsStackDeallocate(10)));
}

TEST_F(X86Core2TargetTest, SetRegToDf1) {
EXPECT_THAT(setRegTo(X86::DF, APInt(1, 1)), ElementsAre(OpcodeIs(X86::STD)));
}

TEST_F(X86Core2TargetTest, SetRegToDf0) {
EXPECT_THAT(setRegTo(X86::DF, APInt(1, 0)), ElementsAre(OpcodeIs(X86::CLD)));
}

TEST_F(X86Core2Avx512TargetTest, FillMemoryOperands_ADD64rm) {
const Instruction &I = getInstr(X86::ADD64rm);
InstructionTemplate IT(&I);
Expand Down
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