[llvm] r343794 - [InstCombine] allow bitcast to/from FP for vector insert/extract transform
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Thu Oct 4 09:25:06 PDT 2018
Author: spatel
Date: Thu Oct 4 09:25:05 2018
New Revision: 343794
URL: http://llvm.org/viewvc/llvm-project?rev=343794&view=rev
Log:
[InstCombine] allow bitcast to/from FP for vector insert/extract transform
This is a follow-up to rL343482 / D52439.
This was a pattern that initially caused the commit to be reverted because
the transform requires a bitcast as shown here.
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
llvm/trunk/test/Transforms/InstCombine/AMDGPU/amdgcn-demanded-vector-elts.ll
llvm/trunk/test/Transforms/InstCombine/extractelement.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp?rev=343794&r1=343793&r2=343794&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp Thu Oct 4 09:25:05 2018
@@ -189,9 +189,7 @@ static Instruction *foldBitcastExtElt(Ex
// If the source elements are wider than the destination, try to shift and
// truncate a subset of scalar bits of an insert op.
- // TODO: This is limited to integer types, but we could bitcast to/from FP.
- if (NumSrcElts < NumElts && SrcTy->getScalarType()->isIntegerTy() &&
- DestTy->getScalarType()->isIntegerTy()) {
+ if (NumSrcElts < NumElts) {
Value *Scalar;
uint64_t InsIndexC;
if (!match(X, m_InsertElement(m_Value(), m_Value(Scalar),
@@ -220,13 +218,42 @@ static Instruction *foldBitcastExtElt(Ex
unsigned Chunk = ExtIndexC % NarrowingRatio;
if (IsBigEndian)
Chunk = NarrowingRatio - 1 - Chunk;
- unsigned ShAmt = Chunk * DestTy->getPrimitiveSizeInBits();
+
+ // Bail out if this is an FP vector to FP vector sequence. That would take
+ // more instructions than we started with unless there is no shift, and it
+ // may not be handled as well in the backend.
+ bool NeedSrcBitcast = SrcTy->getScalarType()->isFloatingPointTy();
+ bool NeedDestBitcast = DestTy->isFloatingPointTy();
+ if (NeedSrcBitcast && NeedDestBitcast)
+ return nullptr;
+
+ unsigned SrcWidth = SrcTy->getScalarSizeInBits();
+ unsigned DestWidth = DestTy->getPrimitiveSizeInBits();
+ unsigned ShAmt = Chunk * DestWidth;
+
+ // TODO: This limitation is more strict than necessary. We could sum the
+ // number of new instructions and subtract the number eliminated to know if
+ // we can proceed.
+ if (!X->hasOneUse() || !Ext.getVectorOperand()->hasOneUse())
+ if (NeedSrcBitcast || NeedDestBitcast)
+ return nullptr;
+
+ if (NeedSrcBitcast) {
+ Type *SrcIntTy = IntegerType::getIntNTy(Scalar->getContext(), SrcWidth);
+ Scalar = Builder.CreateBitCast(Scalar, SrcIntTy);
+ }
+
if (ShAmt) {
// Bail out if we could end with more instructions than we started with.
if (!Ext.getVectorOperand()->hasOneUse())
return nullptr;
Scalar = Builder.CreateLShr(Scalar, ShAmt);
}
+
+ if (NeedDestBitcast) {
+ Type *DestIntTy = IntegerType::getIntNTy(Scalar->getContext(), DestWidth);
+ return new BitCastInst(Builder.CreateTrunc(Scalar, DestIntTy), DestTy);
+ }
return new TruncInst(Scalar, DestTy);
}
Modified: llvm/trunk/test/Transforms/InstCombine/AMDGPU/amdgcn-demanded-vector-elts.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/AMDGPU/amdgcn-demanded-vector-elts.ll?rev=343794&r1=343793&r2=343794&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/AMDGPU/amdgcn-demanded-vector-elts.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/AMDGPU/amdgcn-demanded-vector-elts.ll Thu Oct 4 09:25:05 2018
@@ -299,9 +299,8 @@ define i32 @extract0_bitcast_buffer_load
; CHECK-LABEL: @extract_lo16_0_bitcast_buffer_load_format_v4f32(
; CHECK-NEXT: %tmp = call float @llvm.amdgcn.buffer.load.format.f32(<4 x i32> undef, i32 %arg, i32 16, i1 false, i1 false)
-; CHECK-NEXT: %1 = insertelement <4 x float> undef, float %tmp, i64 0
-; CHECK-NEXT: %tmp1 = bitcast <4 x float> %1 to <8 x i16>
-; CHECK-NEXT: %tmp2 = extractelement <8 x i16> %tmp1, i32 0
+; CHECK-NEXT: %1 = bitcast float %tmp to i32
+; CHECK-NEXT: %tmp2 = trunc i32 %1 to i16
; CHECK-NEXT: ret i16 %tmp2
define i16 @extract_lo16_0_bitcast_buffer_load_format_v4f32(i32 %arg) #0 {
%tmp = call <4 x float> @llvm.amdgcn.buffer.load.format.v4f32(<4 x i32> undef, i32 %arg, i32 16, i1 false, i1 false) #3
Modified: llvm/trunk/test/Transforms/InstCombine/extractelement.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/extractelement.ll?rev=343794&r1=343793&r2=343794&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/extractelement.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/extractelement.ll Thu Oct 4 09:25:05 2018
@@ -164,11 +164,16 @@ define i8 @bitcasted_inselt_wide_source_
}
define float @bitcasted_inselt_to_FP(i64 %x) {
-; ANY-LABEL: @bitcasted_inselt_to_FP(
-; ANY-NEXT: [[I:%.*]] = insertelement <2 x i64> undef, i64 [[X:%.*]], i32 0
-; ANY-NEXT: [[B:%.*]] = bitcast <2 x i64> [[I]] to <4 x float>
-; ANY-NEXT: [[R:%.*]] = extractelement <4 x float> [[B]], i32 1
-; ANY-NEXT: ret float [[R]]
+; LE-LABEL: @bitcasted_inselt_to_FP(
+; LE-NEXT: [[TMP1:%.*]] = lshr i64 [[X:%.*]], 32
+; LE-NEXT: [[TMP2:%.*]] = trunc i64 [[TMP1]] to i32
+; LE-NEXT: [[R:%.*]] = bitcast i32 [[TMP2]] to float
+; LE-NEXT: ret float [[R]]
+;
+; BE-LABEL: @bitcasted_inselt_to_FP(
+; BE-NEXT: [[TMP1:%.*]] = trunc i64 [[X:%.*]] to i32
+; BE-NEXT: [[R:%.*]] = bitcast i32 [[TMP1]] to float
+; BE-NEXT: ret float [[R]]
;
%i = insertelement <2 x i64> undef, i64 %x, i32 0
%b = bitcast <2 x i64> %i to <4 x float>
@@ -210,11 +215,16 @@ define float @bitcasted_inselt_to_FP_use
}
define i32 @bitcasted_inselt_from_FP(double %x) {
-; ANY-LABEL: @bitcasted_inselt_from_FP(
-; ANY-NEXT: [[I:%.*]] = insertelement <2 x double> undef, double [[X:%.*]], i32 0
-; ANY-NEXT: [[B:%.*]] = bitcast <2 x double> [[I]] to <4 x i32>
-; ANY-NEXT: [[R:%.*]] = extractelement <4 x i32> [[B]], i32 1
-; ANY-NEXT: ret i32 [[R]]
+; LE-LABEL: @bitcasted_inselt_from_FP(
+; LE-NEXT: [[TMP1:%.*]] = bitcast double [[X:%.*]] to i64
+; LE-NEXT: [[TMP2:%.*]] = lshr i64 [[TMP1]], 32
+; LE-NEXT: [[R:%.*]] = trunc i64 [[TMP2]] to i32
+; LE-NEXT: ret i32 [[R]]
+;
+; BE-LABEL: @bitcasted_inselt_from_FP(
+; BE-NEXT: [[TMP1:%.*]] = bitcast double [[X:%.*]] to i64
+; BE-NEXT: [[R:%.*]] = trunc i64 [[TMP1]] to i32
+; BE-NEXT: ret i32 [[R]]
;
%i = insertelement <2 x double> undef, double %x, i32 0
%b = bitcast <2 x double> %i to <4 x i32>
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