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/*========================== begin_copyright_notice ============================
Copyright (C) 2024-2025 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
#include "GenX.h"
#include "GenXTargetMachine.h"
#include "GenXUtil.h"
#include "GenXVisa.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/InitializePasses.h"
#define DEBUG_TYPE "GENX_FLOAT_CONTROL"
namespace llvm {
class GenXFloatControl : public FunctionPass {
uint32_t Mask = 0;
bool getFloatControl(Function &F, uint32_t *Val);
Value *buildCr0Update(uint32_t Value, Instruction *InsertBefore);
void buildCr0Write(Value *V, Instruction *InsertBefore);
public:
static char ID;
explicit GenXFloatControl() : FunctionPass(ID) {}
bool runOnFunction(Function &F) override;
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<TargetPassConfig>();
AU.setPreservesAll();
}
StringRef getPassName() const override { return "GenXFloatControl"; }
};
void initializeGenXFloatControlPass(PassRegistry &);
} // namespace llvm
using namespace llvm;
using namespace genx;
using namespace visa;
char GenXFloatControl::ID = 0;
INITIALIZE_PASS_BEGIN(GenXFloatControl, "GenXFloatControl", "GenXFloatControl",
false, false)
INITIALIZE_PASS_DEPENDENCY(TargetPassConfig)
INITIALIZE_PASS_END(GenXFloatControl, "GenXFloatControl", "GenXFloatControl",
false, false)
FunctionPass *llvm::createGenXFloatControlPass() {
initializeGenXFloatControlPass(*PassRegistry::getPassRegistry());
return new GenXFloatControl();
}
bool GenXFloatControl::runOnFunction(Function &F) {
// By default allow to specify with the attribute only
// rounding and denorm modes
Mask = CRBits::RoundingBitMask | CRBits::DoublePrecisionDenorm |
CRBits::SinglePrecisionDenorm | CRBits::HalfPrecisionDenorm;
// Default float control:
// rounding mode = nearest even
// denormals = retain
uint32_t FloatControl = CRBits::RTNE | CRBits::DoublePrecisionDenorm |
CRBits::SinglePrecisionDenorm |
CRBits::HalfPrecisionDenorm;
const auto *Subtarget = &getAnalysis<TargetPassConfig>()
.getTM<GenXTargetMachine>()
.getGenXSubtarget();
if (!getFloatControl(F, &FloatControl) && !fg::isHead(F))
return false;
if (Subtarget->hasSystolicDenormControl()) {
// Always retain denormals in systolic operations
Mask |= CRBits::SystolicDenorm;
FloatControl |= CRBits::SystolicDenorm;
}
// On kernel entry cr0 is set to zero, so in case of zero float control
// we don't need to update it
if (FloatControl == 0 && fg::isGroupHead(F))
return false;
// Kernels, stackcalls and subroutines with attribute set float control on
// entry - provided by the attribute or the default one
auto *OldV = buildCr0Update(FloatControl, F.getEntryBlock().getFirstNonPHI());
if (fg::isGroupHead(F))
return true;
// Stackcalls and subroutines with attribute must save caller's float
// control on entry and restore it before return
for (auto &BB : F)
if (auto *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
buildCr0Write(OldV, RI);
return true;
}
bool GenXFloatControl::getFloatControl(Function &F, uint32_t *Val) {
if (!F.hasFnAttribute(FunctionMD::CMFloatControl))
return false;
F.getFnAttribute(FunctionMD::CMFloatControl)
.getValueAsString()
.getAsInteger(0, *Val);
return true;
}
Value *GenXFloatControl::buildCr0Update(uint32_t Value,
Instruction *InsertBefore) {
IRBuilder<> B(InsertBefore);
auto &DL = InsertBefore->getDebugLoc();
auto *M = InsertBefore->getModule();
auto *Ty = B.getInt32Ty();
auto *VTy = IGCLLVM::FixedVectorType::get(Ty, 4);
auto *Id = B.getInt32(PreDefined_Vars::PREDEFINED_CR0);
Region R(Ty);
auto *ReadPredefDecl =
vc::getAnyDeclaration(M, GenXIntrinsic::genx_read_predef_reg, {VTy, VTy});
auto *WritePredefDecl = vc::getAnyDeclaration(
M, GenXIntrinsic::genx_write_predef_reg, {VTy, VTy});
auto *AndReadPredef =
B.CreateCall(ReadPredefDecl, {Id, UndefValue::get(VTy)});
auto *AndRdRegion =
R.createRdRegion(AndReadPredef, "", InsertBefore, DL, true);
auto *And = B.CreateAnd(AndRdRegion, ~Mask);
auto *AndWrRegion =
R.createWrRegion(AndReadPredef, And, "", InsertBefore, DL);
B.CreateCall(WritePredefDecl, {Id, AndWrRegion});
auto *OrReadPredef = B.CreateCall(ReadPredefDecl, {Id, UndefValue::get(VTy)});
auto *OrRdRegion = R.createRdRegion(OrReadPredef, "", InsertBefore, DL, true);
auto *Or = B.CreateOr(OrRdRegion, Value & Mask);
auto *OrWrRegion = R.createWrRegion(OrReadPredef, Or, "", InsertBefore, DL);
B.CreateCall(WritePredefDecl, {Id, OrWrRegion});
return AndRdRegion;
}
void GenXFloatControl::buildCr0Write(Value *V, Instruction *InsertBefore) {
IRBuilder<> B(InsertBefore);
auto &DL = InsertBefore->getDebugLoc();
auto *M = InsertBefore->getModule();
auto *Ty = B.getInt32Ty();
auto *VTy = IGCLLVM::FixedVectorType::get(Ty, 4);
auto *Id = B.getInt32(PreDefined_Vars::PREDEFINED_CR0);
Region R(Ty);
auto *ReadPredefDecl =
vc::getAnyDeclaration(M, GenXIntrinsic::genx_read_predef_reg, {VTy, VTy});
auto *WritePredefDecl = vc::getAnyDeclaration(
M, GenXIntrinsic::genx_write_predef_reg, {VTy, VTy});
auto *ReadPredef = B.CreateCall(ReadPredefDecl, {Id, UndefValue::get(VTy)});
auto *WrRegion = R.createWrRegion(ReadPredef, V, "", InsertBefore, DL);
B.CreateCall(WritePredefDecl, {Id, WrRegion});
}
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