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[ESIMD] Break @llvm.fmuladd back into mul/add to satisfy VC BE. #5075

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Merged
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Dec 4, 2021
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[ESIMD] Break @llvm.fmuladd back into mul/add to satisfy VC BE. #5075

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39 changes: 37 additions & 2 deletions llvm/lib/SYCLLowerIR/LowerESIMD.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -978,6 +978,39 @@ static Instruction *generateGenXCall(ExtractElementInst *EEI,
return Inst;
}

// Translates the following intrinsics:
// %res = call float @llvm.fmuladd.f32(float %a, float %b, float %c)
// %res = call double @llvm.fmuladd.f64(double %a, double %b, double %c)
// To
// %mul = fmul <type> %a, <type> %b
// %res = fadd <type> %mul, <type> %c
void translateFmuladd(CallInst *CI) {
assert(CI->getIntrinsicID() == Intrinsic::fmuladd);
IRBuilder<> Bld(CI);
auto *Mul = Bld.CreateFMul(CI->getOperand(0), CI->getOperand(1));
auto *Res = Bld.CreateFAdd(Mul, CI->getOperand(2));
CI->replaceAllUsesWith(Res);
}

// Translates an LLVM intrinsic to a form, digestable by the BE.
bool translateLLVMIntrinsic(CallInst *CI) {
Function *F = CI->getCalledFunction() ? CI->getCalledFunction() : nullptr;
assert(F && F->isIntrinsic());

switch (F->getIntrinsicID()) {
case Intrinsic::assume:
// no translation - it will be simply removed.
// TODO: make use of 'assume' info in the BE
break;
case Intrinsic::fmuladd:
translateFmuladd(CI);
break;
default:
return false; // "intrinsic wasn't translated, keep the original call"
}
return true; // "intrinsic has been translated, erase the original call"
}

/// Replaces the load \p LI of SPIRV global with corresponding call(s) of GenX
/// intrinsic(s). The users of \p LI may also be transformed if needed for
/// def/use type correctness.
Expand Down Expand Up @@ -1469,8 +1502,10 @@ size_t SYCLLowerESIMDPass::runOnFunction(Function &F,
Function *Callee = nullptr;
if (CI && (Callee = CI->getCalledFunction())) {
// TODO workaround for ESIMD BE until it starts supporting @llvm.assume
if (match(&I, PatternMatch::m_Intrinsic<Intrinsic::assume>())) {
ToErase.push_back(CI);
if (Callee->isIntrinsic()) {
if (translateLLVMIntrinsic(CI)) {
ToErase.push_back(CI);
}
continue;
}
StringRef Name = Callee->getName();
Expand Down
26 changes: 26 additions & 0 deletions llvm/test/SYCLLowerIR/esimd_lower_llvm_intrin.ll
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@@ -0,0 +1,26 @@
; RUN: opt -LowerESIMD -S < %s | FileCheck %s

; This test checks that LowerESIMD pass correctly lowers some llvm intrinsics
; which can't be handled by the VC BE.
target datalayout = "e-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-n8:16:32:64"
target triple = "spir64-unknown-unknown"

declare float @llvm.fmuladd.f32(float %x, float %y, float %z)
declare double @llvm.fmuladd.f64(double %x, double %y, double %z)

define spir_func float @test_fmuladd_f32(float %x, float %y, float %z) {
%1 = call float @llvm.fmuladd.f32(float %x, float %y, float %z)
; CHECK: %[[A:[0-9a-zA-Z\._]+]] = fmul float %x, %y
; CHECK: %[[B:[0-9a-zA-Z\._]+]] = fadd float %[[A]], %z
ret float %1
; CHECK: ret float %[[B]]
}

define spir_func double @test_fmuladd_f64(double %x, double %y, double %z) {
%1 = call double @llvm.fmuladd.f64(double %x, double %y, double %z)
; CHECK: %[[A:[0-9a-zA-Z\._]+]] = fmul double %x, %y
; CHECK: %[[B:[0-9a-zA-Z\._]+]] = fadd double %[[A]], %z
ret double %1
; CHECK: ret double %[[B]]
}