[llvm] r314117 - [InstCombine] remove extract-of-select vector transform
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Mon Sep 25 09:41:34 PDT 2017
Author: spatel
Date: Mon Sep 25 09:41:34 2017
New Revision: 314117
URL: http://llvm.org/viewvc/llvm-project?rev=314117&view=rev
Log:
[InstCombine] remove extract-of-select vector transform
The transform to convert an extract-of-a-select-of-vectors was added at:
rL194013
And a question about the validity of this transform was raised in the review:
https://reviews.llvm.org/D1539:
...but not answered AFAICT>
Most of the motivating cases in that patch are now handled by other combines. These are the tests that were added with
the original commit, but they are not regressing even after we remove the transform in this patch.
The diffs we see after removing this transform cause us to avoid increasing the instruction count, so we don't want to do
those transforms as canonicalizations.
The motivation for not turning a vector-select-of-vectors into a scalar operation is shown in PR33301:
https://bugs.llvm.org/show_bug.cgi?id=33301
...in those cases, we'll get vector ops with this patch rather than the vector/scalar mix that we currently see.
Differential Revision: https://reviews.llvm.org/D38006
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
llvm/trunk/test/Transforms/InstCombine/select-extractelement.ll
llvm/trunk/test/Transforms/LoopVectorize/minmax_reduction.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp?rev=314117&r1=314116&r2=314117&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp Mon Sep 25 09:41:34 2017
@@ -255,39 +255,6 @@ Instruction *InstCombiner::visitExtractE
Worklist.AddValue(EE);
return CastInst::Create(CI->getOpcode(), EE, EI.getType());
}
- } else if (SelectInst *SI = dyn_cast<SelectInst>(I)) {
- if (SI->hasOneUse()) {
- // TODO: For a select on vectors, it might be useful to do this if it
- // has multiple extractelement uses. For vector select, that seems to
- // fight the vectorizer.
-
- // If we are extracting an element from a vector select or a select on
- // vectors, create a select on the scalars extracted from the vector
- // arguments.
- Value *TrueVal = SI->getTrueValue();
- Value *FalseVal = SI->getFalseValue();
-
- Value *Cond = SI->getCondition();
- if (Cond->getType()->isVectorTy()) {
- Cond = Builder.CreateExtractElement(Cond,
- EI.getIndexOperand(),
- Cond->getName() + ".elt");
- }
-
- Value *V1Elem
- = Builder.CreateExtractElement(TrueVal,
- EI.getIndexOperand(),
- TrueVal->getName() + ".elt");
-
- Value *V2Elem
- = Builder.CreateExtractElement(FalseVal,
- EI.getIndexOperand(),
- FalseVal->getName() + ".elt");
- return SelectInst::Create(Cond,
- V1Elem,
- V2Elem,
- SI->getName() + ".elt");
- }
}
}
return nullptr;
Modified: llvm/trunk/test/Transforms/InstCombine/select-extractelement.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/select-extractelement.ll?rev=314117&r1=314116&r2=314117&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/select-extractelement.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/select-extractelement.ll Mon Sep 25 09:41:34 2017
@@ -5,9 +5,8 @@ declare void @v4float_user(<4 x float>)
define float @extract_one_select(<4 x float> %a, <4 x float> %b, i32 %c) #0 {
; CHECK-LABEL: @extract_one_select(
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 %c, 0
-; CHECK-NEXT: [[B_ELT:%.*]] = extractelement <4 x float> %b, i32 2
-; CHECK-NEXT: [[A_ELT:%.*]] = extractelement <4 x float> %a, i32 2
-; CHECK-NEXT: [[EXTRACT:%.*]] = select i1 [[CMP]], float [[B_ELT]], float [[A_ELT]]
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], <4 x float> %b, <4 x float> %a
+; CHECK-NEXT: [[EXTRACT:%.*]] = extractelement <4 x float> [[SEL]], i32 2
; CHECK-NEXT: ret float [[EXTRACT]]
;
%cmp = icmp ne i32 %c, 0
@@ -64,14 +63,14 @@ define float @extract_one_vselect_user(<
ret float %extract
}
-; Extract from a vector select
+; Do not convert the vector select into a scalar select. That would increase
+; the instruction count and potentially obfuscate a vector min/max idiom.
+
define float @extract_one_vselect(<4 x float> %a, <4 x float> %b, <4 x i32> %c) #0 {
; CHECK-LABEL: @extract_one_vselect(
; CHECK-NEXT: [[CMP:%.*]] = icmp eq <4 x i32> %c, zeroinitializer
-; CHECK-NEXT: [[CMP_ELT:%.*]] = extractelement <4 x i1> [[CMP]], i32 0
-; CHECK-NEXT: [[B_ELT:%.*]] = extractelement <4 x float> %b, i32 0
-; CHECK-NEXT: [[A_ELT:%.*]] = extractelement <4 x float> %a, i32 0
-; CHECK-NEXT: [[EXTRACT:%.*]] = select i1 [[CMP_ELT]], float [[B_ELT]], float [[A_ELT]]
+; CHECK-NEXT: [[SELECT:%.*]] = select <4 x i1> [[CMP]], <4 x float> %b, <4 x float> %a
+; CHECK-NEXT: [[EXTRACT:%.*]] = extractelement <4 x float> [[SELECT]], i32 0
; CHECK-NEXT: ret float [[EXTRACT]]
;
%cmp = icmp ne <4 x i32> %c, zeroinitializer
@@ -97,36 +96,28 @@ define <2 x float> @extract_two_vselect(
ret <2 x float> %build2
}
-; All the vector selects should be decomposed into scalar selects
+; The vector selects are not decomposed into scalar selects because that would increase
+; the instruction count. Extract+insert is converted to non-lane-crossing shuffles.
; Test multiple extractelements
define <4 x float> @simple_vector_select(<4 x float> %a, <4 x float> %b, <4 x i32> %c) #0 {
; CHECK-LABEL: @simple_vector_select(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = extractelement <4 x i32> %c, i32 0
; CHECK-NEXT: [[TOBOOL:%.*]] = icmp eq i32 [[TMP0]], 0
-; CHECK-NEXT: [[B_ELT:%.*]] = extractelement <4 x float> %b, i32 0
-; CHECK-NEXT: [[A_ELT:%.*]] = extractelement <4 x float> %a, i32 0
-; CHECK-NEXT: [[TMP1:%.*]] = select i1 [[TOBOOL]], float [[B_ELT]], float [[A_ELT]]
-; CHECK-NEXT: [[TMP2:%.*]] = insertelement <4 x float> undef, float [[TMP1]], i32 0
-; CHECK-NEXT: [[TMP3:%.*]] = extractelement <4 x i32> %c, i32 1
-; CHECK-NEXT: [[TOBOOL1:%.*]] = icmp eq i32 [[TMP3]], 0
-; CHECK-NEXT: [[B_ELT1:%.*]] = extractelement <4 x float> %b, i32 1
-; CHECK-NEXT: [[A_ELT2:%.*]] = extractelement <4 x float> %a, i32 1
-; CHECK-NEXT: [[TMP4:%.*]] = select i1 [[TOBOOL1]], float [[B_ELT1]], float [[A_ELT2]]
-; CHECK-NEXT: [[TMP5:%.*]] = insertelement <4 x float> [[TMP2]], float [[TMP4]], i32 1
-; CHECK-NEXT: [[TMP6:%.*]] = extractelement <4 x i32> %c, i32 2
-; CHECK-NEXT: [[TOBOOL6:%.*]] = icmp eq i32 [[TMP6]], 0
-; CHECK-NEXT: [[B_ELT3:%.*]] = extractelement <4 x float> %b, i32 2
-; CHECK-NEXT: [[A_ELT4:%.*]] = extractelement <4 x float> %a, i32 2
-; CHECK-NEXT: [[TMP7:%.*]] = select i1 [[TOBOOL6]], float [[B_ELT3]], float [[A_ELT4]]
-; CHECK-NEXT: [[TMP8:%.*]] = insertelement <4 x float> [[TMP5]], float [[TMP7]], i32 2
-; CHECK-NEXT: [[TMP9:%.*]] = extractelement <4 x i32> %c, i32 3
-; CHECK-NEXT: [[TOBOOL11:%.*]] = icmp eq i32 [[TMP9]], 0
-; CHECK-NEXT: [[B_ELT5:%.*]] = extractelement <4 x float> %b, i32 3
-; CHECK-NEXT: [[A_ELT6:%.*]] = extractelement <4 x float> %a, i32 3
-; CHECK-NEXT: [[TMP10:%.*]] = select i1 [[TOBOOL11]], float [[B_ELT5]], float [[A_ELT6]]
-; CHECK-NEXT: [[TMP11:%.*]] = insertelement <4 x float> [[TMP8]], float [[TMP10]], i32 3
-; CHECK-NEXT: ret <4 x float> [[TMP11]]
+; CHECK-NEXT: [[A_SINK:%.*]] = select i1 [[TOBOOL]], <4 x float> %b, <4 x float> %a
+; CHECK-NEXT: [[TMP1:%.*]] = extractelement <4 x i32> %c, i32 1
+; CHECK-NEXT: [[TOBOOL1:%.*]] = icmp eq i32 [[TMP1]], 0
+; CHECK-NEXT: [[A_SINK1:%.*]] = select i1 [[TOBOOL1]], <4 x float> %b, <4 x float> %a
+; CHECK-NEXT: [[TMP2:%.*]] = shufflevector <4 x float> [[A_SINK]], <4 x float> [[A_SINK1]], <4 x i32> <i32 0, i32 5, i32 undef, i32 undef>
+; CHECK-NEXT: [[TMP3:%.*]] = extractelement <4 x i32> %c, i32 2
+; CHECK-NEXT: [[TOBOOL6:%.*]] = icmp eq i32 [[TMP3]], 0
+; CHECK-NEXT: [[A_SINK2:%.*]] = select i1 [[TOBOOL6]], <4 x float> %b, <4 x float> %a
+; CHECK-NEXT: [[TMP4:%.*]] = shufflevector <4 x float> [[TMP2]], <4 x float> [[A_SINK2]], <4 x i32> <i32 0, i32 1, i32 6, i32 undef>
+; CHECK-NEXT: [[TMP5:%.*]] = extractelement <4 x i32> %c, i32 3
+; CHECK-NEXT: [[TOBOOL11:%.*]] = icmp eq i32 [[TMP5]], 0
+; CHECK-NEXT: [[A_SINK3:%.*]] = select i1 [[TOBOOL11]], <4 x float> %b, <4 x float> %a
+; CHECK-NEXT: [[TMP6:%.*]] = shufflevector <4 x float> [[TMP4]], <4 x float> [[A_SINK3]], <4 x i32> <i32 0, i32 1, i32 2, i32 7>
+; CHECK-NEXT: ret <4 x float> [[TMP6]]
;
entry:
%0 = extractelement <4 x i32> %c, i32 0
Modified: llvm/trunk/test/Transforms/LoopVectorize/minmax_reduction.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopVectorize/minmax_reduction.ll?rev=314117&r1=314116&r2=314117&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopVectorize/minmax_reduction.ll (original)
+++ llvm/trunk/test/Transforms/LoopVectorize/minmax_reduction.ll Mon Sep 25 09:41:34 2017
@@ -17,7 +17,7 @@ target datalayout = "e-p:64:64:64-i1:8:8
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: icmp sgt <2 x i32>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define i32 @max_red(i32 %max) {
entry:
@@ -46,7 +46,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: icmp sgt <2 x i32>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define i32 @max_red_inverse_select(i32 %max) {
entry:
@@ -74,7 +74,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: icmp slt <2 x i32>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define i32 @min_red(i32 %max) {
entry:
@@ -103,7 +103,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: icmp slt <2 x i32>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define i32 @min_red_inverse_select(i32 %max) {
entry:
@@ -133,7 +133,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: icmp ugt <2 x i32>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define i32 @umax_red(i32 %max) {
entry:
@@ -162,7 +162,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: icmp ugt <2 x i32>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define i32 @umax_red_inverse_select(i32 %max) {
entry:
@@ -190,7 +190,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: icmp ult <2 x i32>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define i32 @umin_red(i32 %max) {
entry:
@@ -219,7 +219,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: icmp ult <2 x i32>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define i32 @umin_red_inverse_select(i32 %max) {
entry:
@@ -248,7 +248,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: icmp slt <2 x i32>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define i32 @sge_min_red(i32 %max) {
entry:
@@ -277,7 +277,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: icmp sgt <2 x i32>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define i32 @sle_min_red(i32 %max) {
entry:
@@ -306,7 +306,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: icmp ult <2 x i32>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define i32 @uge_min_red(i32 %max) {
entry:
@@ -335,7 +335,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: icmp ugt <2 x i32>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define i32 @ule_min_red(i32 %max) {
entry:
@@ -416,7 +416,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast ogt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @max_red_float(float %max) #0 {
entry:
@@ -442,7 +442,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast ogt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @max_red_float_ge(float %max) #0 {
entry:
@@ -468,7 +468,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast ogt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @inverted_max_red_float(float %max) #0 {
entry:
@@ -494,7 +494,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast ogt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @inverted_max_red_float_le(float %max) #0 {
entry:
@@ -520,7 +520,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast ogt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @unordered_max_red_float(float %max) #0 {
entry:
@@ -546,7 +546,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast ogt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @unordered_max_red_float_ge(float %max) #0 {
entry:
@@ -572,7 +572,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast ogt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @inverted_unordered_max_red_float(float %max) #0 {
entry:
@@ -598,7 +598,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast ogt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @inverted_unordered_max_red_float_le(float %max) #0 {
entry:
@@ -627,7 +627,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast olt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @min_red_float(float %min) #0 {
entry:
@@ -653,7 +653,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast olt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @min_red_float_le(float %min) #0 {
entry:
@@ -679,7 +679,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast olt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @inverted_min_red_float(float %min) #0 {
entry:
@@ -705,7 +705,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast olt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @inverted_min_red_float_ge(float %min) #0 {
entry:
@@ -731,7 +731,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast olt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @unordered_min_red_float(float %min) #0 {
entry:
@@ -757,7 +757,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast olt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @unordered_min_red_float_le(float %min) #0 {
entry:
@@ -783,7 +783,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast olt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @inverted_unordered_min_red_float(float %min) #0 {
entry:
@@ -809,7 +809,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast olt <2 x float>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define float @inverted_unordered_min_red_float_ge(float %min) #0 {
entry:
@@ -836,7 +836,7 @@ for.end:
; CHECK: select <2 x i1>
; CHECK: middle.block
; CHECK: fcmp fast olt <2 x double>
-; CHECK: select i1
+; CHECK: select <2 x i1>
define double @min_red_double(double %min) #0 {
entry:
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