[LoopVectorizer] Don't create unused block masks for reductions. NFC

This removes some unneeded block masks when we don't have any reductions. It should not have any effect on codegen as the values created are dead anyway. Differential Revision: https://reviews.llvm.org/D81415
llvm · Jul 30, 2020 · 1da0c47 · 1da0c47
1 parent 9be1bdc
commit 1da0c47
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Showing 3 changed files with 8 additions and 21 deletions.
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -7459,7 +7459,7 @@ VPlanPtr LoopVectorizationPlanner::buildVPlanWithVPRecipes(
 
   // Finally, if tail is folded by masking, introduce selects between the phi
   // and the live-out instruction of each reduction, at the end of the latch.
-  if (CM.foldTailByMasking()) {
+  if (CM.foldTailByMasking() && !Legal->getReductionVars().empty()) {
     Builder.setInsertPoint(VPBB);
     auto *Cond = RecipeBuilder.createBlockInMask(OrigLoop->getHeader(), Plan);
     for (auto &Reduction : Legal->getReductionVars()) {

diff --git a/llvm/test/Transforms/LoopVectorize/icmp-uniforms.ll b/llvm/test/Transforms/LoopVectorize/icmp-uniforms.ll
@@ -39,8 +39,7 @@ for.end:
 ; CHECK-NEXT:    "loop:\n" +
 ; CHECK-NEXT:      "WIDEN-INDUCTION %iv = phi 0, %iv.next\l" +
 ; CHECK-NEXT:      "WIDEN\l""  %cond0 = icmp %iv, 13\l" +
-; CHECK-NEXT:      "WIDEN-SELECT%s = select %cond0, 10, 20\l" +
-; CHECK-NEXT:      "EMIT vp<%1> = icmp ule ir<%iv> vp<%0>\l"
+; CHECK-NEXT:      "WIDEN-SELECT%s = select %cond0, 10, 20\l"
 ; CHECK-NEXT:  ]
 define void @test() {
 entry:

diff --git a/llvm/test/Transforms/LoopVectorize/tail-folding-vectorization-factor-1.ll b/llvm/test/Transforms/LoopVectorize/tail-folding-vectorization-factor-1.ll
@@ -10,7 +10,7 @@
 ; CHECK-REMARKS-NOT:  remark: {{.*}} vectorized loop
 
 define void @VF1-VPlanExe() {
-; CHECK-LABEL: @VF1-VPlanExe
+; CHECK-LABEL: @VF1-VPlanExe(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
 ; CHECK:       vector.ph:
@@ -21,13 +21,9 @@ define void @VF1-VPlanExe() {
 ; CHECK-NEXT:    [[INDUCTION1:%.*]] = add i64 [[INDEX]], 1
 ; CHECK-NEXT:    [[INDUCTION2:%.*]] = add i64 [[INDEX]], 2
 ; CHECK-NEXT:    [[INDUCTION3:%.*]] = add i64 [[INDEX]], 3
-; CHECK-NEXT:    [[TMP0:%.*]] = icmp ule i64 [[INDUCTION]], 14
-; CHECK-NEXT:    [[TMP1:%.*]] = icmp ule i64 [[INDUCTION1]], 14
-; CHECK-NEXT:    [[TMP2:%.*]] = icmp ule i64 [[INDUCTION2]], 14
-; CHECK-NEXT:    [[TMP3:%.*]] = icmp ule i64 [[INDUCTION3]], 14
 ; CHECK-NEXT:    [[INDEX_NEXT]] = add i64 [[INDEX]], 4
-; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i64 [[INDEX_NEXT]], 16
-; CHECK-NEXT:    br i1 [[TMP4]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop !0
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i64 [[INDEX_NEXT]], 16
+; CHECK-NEXT:    br i1 [[TMP0]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop !0
 ; CHECK:       middle.block:
 ; CHECK-NEXT:    br i1 true, label [[FOR_COND_CLEANUP:%.*]], label [[SCALAR_PH]]
 ; CHECK:       scalar.ph:
@@ -55,7 +51,7 @@ for.body:
 }
 
 define void @VF1-VPWidenCanonicalIVRecipeExe(double* %ptr1) {
-; CHECK-LABEL: @VF1-VPWidenCanonicalIVRecipeExe
+; CHECK-LABEL: @VF1-VPWidenCanonicalIVRecipeExe(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[PTR2:%.*]] = getelementptr inbounds double, double* [[PTR1:%.*]], i64 15
 ; CHECK-NEXT:    br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
@@ -72,17 +68,9 @@ define void @VF1-VPWidenCanonicalIVRecipeExe(double* %ptr1) {
 ; CHECK-NEXT:    [[NEXT_GEP2:%.*]] = getelementptr double, double* [[PTR1]], i64 [[TMP2]]
 ; CHECK-NEXT:    [[TMP3:%.*]] = add i64 [[INDEX]], 3
 ; CHECK-NEXT:    [[NEXT_GEP3:%.*]] = getelementptr double, double* [[PTR1]], i64 [[TMP3]]
-; CHECK-NEXT:    [[VEC_IV:%.*]] = add i64 [[INDEX]], 0
-; CHECK-NEXT:    [[VEC_IV4:%.*]] = add i64 [[INDEX]], 1
-; CHECK-NEXT:    [[VEC_IV5:%.*]] = add i64 [[INDEX]], 2
-; CHECK-NEXT:    [[VEC_IV6:%.*]] = add i64 [[INDEX]], 3
-; CHECK-NEXT:    [[TMP4:%.*]] = icmp ule i64 [[VEC_IV]], 14
-; CHECK-NEXT:    [[TMP5:%.*]] = icmp ule i64 [[VEC_IV4]], 14
-; CHECK-NEXT:    [[TMP6:%.*]] = icmp ule i64 [[VEC_IV5]], 14
-; CHECK-NEXT:    [[TMP7:%.*]] = icmp ule i64 [[VEC_IV6]], 14
 ; CHECK-NEXT:    [[INDEX_NEXT]] = add i64 [[INDEX]], 4
-; CHECK-NEXT:    [[TMP8:%.*]] = icmp eq i64 [[INDEX_NEXT]], 16
-; CHECK-NEXT:    br i1 [[TMP8]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop !3
+; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i64 [[INDEX_NEXT]], 16
+; CHECK-NEXT:    br i1 [[TMP4]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop !3
 ; CHECK:       middle.block:
 ; CHECK-NEXT:    br i1 true, label [[FOR_COND_CLEANUP:%.*]], label [[SCALAR_PH]]
 ; CHECK:       scalar.ph: