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[DXIL] Implement log intrinsic Lowering
Completes #86192 `DXIL.td` - add log2 to dxilop lowering `DXILIntrinsicExpansion.cpp` - add log and log10 to log2 expansions
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6 files changed

+117
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lines changed

‎llvm/lib/Target/DirectX/DXIL.td

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -274,6 +274,9 @@ def Frac : DXILOpMapping<22, unary, int_dx_frac,
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"Returns a fraction from 0 to 1 that represents the "
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"decimal part of the input.",
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[llvm_halforfloat_ty, LLVMMatchType<0>]>;
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def Log2 : DXILOpMapping<23, unary, int_log2,
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"Returns the base-2 logarithm of the specified value.",
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[llvm_halforfloat_ty, LLVMMatchType<0>]>;
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def Sqrt : DXILOpMapping<24, unary, int_sqrt,
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"Returns the square root of the specified floating-point"
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"value, per component.",

‎llvm/lib/Target/DirectX/DXILIntrinsicExpansion.cpp

Lines changed: 34 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -35,6 +35,8 @@ static bool isIntrinsicExpansion(Function &F) {
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switch (F.getIntrinsicID()) {
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case Intrinsic::abs:
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case Intrinsic::exp:
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case Intrinsic::log:
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case Intrinsic::log10:
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case Intrinsic::dx_any:
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case Intrinsic::dx_clamp:
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case Intrinsic::dx_uclamp:
@@ -108,8 +110,8 @@ static bool expandExpIntrinsic(CallInst *Orig) {
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Ty->isVectorTy() ? ConstantVector::getSplat(
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ElementCount::getFixed(
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cast<FixedVectorType>(Ty)->getNumElements()),
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ConstantFP::get(EltTy, numbers::log2e))
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: ConstantFP::get(EltTy, numbers::log2e);
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ConstantFP::get(EltTy, numbers::log2ef))
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: ConstantFP::get(EltTy, numbers::log2ef);
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Value *NewX = Builder.CreateFMul(Log2eConst, X);
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auto *Exp2Call =
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Builder.CreateIntrinsic(Ty, Intrinsic::exp2, {NewX}, nullptr, "dx.exp2");
@@ -169,6 +171,32 @@ static bool expandLerpIntrinsic(CallInst *Orig) {
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return true;
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}
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static bool expandLogIntrinsic(CallInst *Orig,
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float LogConstVal = numbers::ln2f) {
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Value *X = Orig->getOperand(0);
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IRBuilder<> Builder(Orig->getParent());
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Builder.SetInsertPoint(Orig);
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Type *Ty = X->getType();
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Type *EltTy = Ty->getScalarType();
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Constant *Ln2Const =
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Ty->isVectorTy() ? ConstantVector::getSplat(
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ElementCount::getFixed(
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cast<FixedVectorType>(Ty)->getNumElements()),
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ConstantFP::get(EltTy, LogConstVal))
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: ConstantFP::get(EltTy, LogConstVal);
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auto *Log2Call =
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Builder.CreateIntrinsic(Ty, Intrinsic::log2, {X}, nullptr, "elt.log2");
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Log2Call->setTailCall(Orig->isTailCall());
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Log2Call->setAttributes(Orig->getAttributes());
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auto *Result = Builder.CreateFMul(Ln2Const, Log2Call);
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Orig->replaceAllUsesWith(Result);
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Orig->eraseFromParent();
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return true;
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}
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static bool expandLog10Intrinsic(CallInst *Orig) {
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return expandLogIntrinsic(Orig, numbers::ln2f / numbers::ln10f);
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}
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static bool expandRcpIntrinsic(CallInst *Orig) {
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Value *X = Orig->getOperand(0);
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IRBuilder<> Builder(Orig->getParent());
@@ -238,6 +266,10 @@ static bool expandIntrinsic(Function &F, CallInst *Orig) {
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return expandAbs(Orig);
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case Intrinsic::exp:
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return expandExpIntrinsic(Orig);
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case Intrinsic::log:
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return expandLogIntrinsic(Orig);
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case Intrinsic::log10:
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return expandLog10Intrinsic(Orig);
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case Intrinsic::dx_any:
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return expandAnyIntrinsic(Orig);
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case Intrinsic::dx_uclamp:

‎llvm/test/CodeGen/DirectX/log.ll

Lines changed: 25 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,25 @@
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; RUN: opt -S -dxil-intrinsic-expansion < %s | FileCheck %s --check-prefixes=CHECK,EXPCHECK
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; RUN: opt -S -dxil-op-lower < %s | FileCheck %s --check-prefixes=CHECK,DOPCHECK
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; Make sure dxil operation function calls for log are generated.
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define noundef float @log_float(float noundef %a) #0 {
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entry:
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; DOPCHECK: call float @dx.op.unary.f32(i32 23, float %{{.*}})
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; EXPCHECK: call float @llvm.log2.f32(float %a)
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; CHECK: fmul float 0x3FE62E4300000000, %{{.*}}
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%elt.log = call float @llvm.log.f32(float %a)
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ret float %elt.log
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}
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define noundef half @log_half(half noundef %a) #0 {
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entry:
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; DOPCHECK: call half @dx.op.unary.f16(i32 23, half %{{.*}})
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; EXPCHECK: call half @llvm.log2.f16(half %a)
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; CHECK: fmul half 0xH398C, %{{.*}}
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%elt.log = call half @llvm.log.f16(half %a)
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ret half %elt.log
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}
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declare half @llvm.log.f16(half)
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declare float @llvm.log.f32(float)

‎llvm/test/CodeGen/DirectX/log10.ll

Lines changed: 25 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,25 @@
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; RUN: opt -S -dxil-intrinsic-expansion < %s | FileCheck %s --check-prefixes=CHECK,EXPCHECK
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; RUN: opt -S -dxil-op-lower < %s | FileCheck %s --check-prefixes=CHECK,DOPCHECK
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4+
; Make sure dxil operation function calls for log10 are generated.
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define noundef float @log10_float(float noundef %a) #0 {
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entry:
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; DOPCHECK: call float @dx.op.unary.f32(i32 23, float %{{.*}})
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; EXPCHECK: call float @llvm.log2.f32(float %a)
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; CHECK: fmul float 0x3FD3441340000000, %{{.*}}
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%elt.log10 = call float @llvm.log10.f32(float %a)
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ret float %elt.log10
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}
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15+
define noundef half @log10_half(half noundef %a) #0 {
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entry:
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; DOPCHECK: call half @dx.op.unary.f16(i32 23, half %{{.*}})
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; EXPCHECK: call half @llvm.log2.f16(half %a)
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; CHECK: fmul half 0xH34D1, %{{.*}}
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%elt.log10 = call half @llvm.log10.f16(half %a)
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ret half %elt.log10
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}
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24+
declare half @llvm.log10.f16(half)
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declare float @llvm.log10.f32(float)

‎llvm/test/CodeGen/DirectX/log2.ll

Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,20 @@
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; RUN: opt -S -dxil-op-lower < %s | FileCheck %s
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; Make sure dxil operation function calls for log2 are generated for float and half.
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define noundef float @log2_float(float noundef %a) #0 {
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entry:
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; CHECK:call float @dx.op.unary.f32(i32 23, float %{{.*}})
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%elt.log2 = call float @llvm.log2.f32(float %a)
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ret float %elt.log2
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}
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define noundef half @log2_half(half noundef %a) #0 {
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entry:
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; CHECK:call half @dx.op.unary.f16(i32 23, half %{{.*}})
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%elt.log2 = call half @llvm.log2.f16(half %a)
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ret half %elt.log2
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}
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19+
declare half @llvm.log2.f16(half)
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declare float @llvm.log2.f32(float)

‎llvm/test/CodeGen/DirectX/log2_error.ll

Lines changed: 10 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,10 @@
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; RUN: not opt -S -dxil-op-lower %s 2>&1 | FileCheck %s
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; DXIL operation log2 does not support double overload type
4+
; CHECK: LLVM ERROR: Invalid Overload Type
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6+
define noundef double @log2_double(double noundef %a) {
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entry:
8+
%elt.log2 = call double @llvm.log2.f64(double %a)
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ret double %elt.log2
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}

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