[llvm] [VPlan] Mark ComputeReductionResult as not reading or writing from memory (PR #212982)

[via llvm-commits]

llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Luke Lau (lukel97)

<details>
<summary>Changes</summary>

Enables some DCE


---
Full diff: https://github.com/llvm/llvm-project/pull/212982.diff


3 Files Affected:

- (modified) llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp (+1) 
- (modified) llvm/test/Transforms/LoopVectorize/epilog-vectorization-reductions.ll (-2) 
- (modified) llvm/test/Transforms/LoopVectorize/select-cmp-blend-chain.ll (-4) 


``````````diff
diff --git a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
index 5127c5963b02e..7a4c8f316e89d 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
@@ -1622,6 +1622,7 @@ bool VPInstruction::opcodeMayReadOrWriteFromMemory() const {
   case VPInstruction::BuildVector:
   case VPInstruction::CalculateTripCountMinusVF:
   case VPInstruction::CanonicalIVIncrementForPart:
+  case VPInstruction::ComputeReductionResult:
   case VPInstruction::ExtractLane:
   case VPInstruction::ExtractLastLane:
   case VPInstruction::ExtractLastPart:
diff --git a/llvm/test/Transforms/LoopVectorize/epilog-vectorization-reductions.ll b/llvm/test/Transforms/LoopVectorize/epilog-vectorization-reductions.ll
index 20e18d018892a..846c78db79100 100644
--- a/llvm/test/Transforms/LoopVectorize/epilog-vectorization-reductions.ll
+++ b/llvm/test/Transforms/LoopVectorize/epilog-vectorization-reductions.ll
@@ -1115,7 +1115,6 @@ define i32 @test_foldable_reduction(i64 %N) {
 ; CHECK-NEXT:    br i1 [[TMP1]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP32:![0-9]+]]
 ; CHECK:       [[MIDDLE_BLOCK]]:
 ; CHECK-NEXT:    [[TMP2:%.*]] = call i32 @llvm.vector.reduce.or.v8i32(<8 x i32> [[VEC_PHI]])
-; CHECK-NEXT:    [[TMP3:%.*]] = call i1 @llvm.vector.reduce.or.v8i1(<8 x i1> splat (i1 true))
 ; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i64 [[TMP0]], [[N_VEC]]
 ; CHECK-NEXT:    br i1 [[CMP_N]], label %[[EXIT:.*]], label %[[VEC_EPILOG_ITER_CHECK:.*]]
 ; CHECK:       [[VEC_EPILOG_ITER_CHECK]]:
@@ -1136,7 +1135,6 @@ define i32 @test_foldable_reduction(i64 %N) {
 ; CHECK-NEXT:    br i1 [[TMP6]], label %[[VEC_EPILOG_MIDDLE_BLOCK:.*]], label %[[VEC_EPILOG_VECTOR_BODY]], !llvm.loop [[LOOP33:![0-9]+]]
 ; CHECK:       [[VEC_EPILOG_MIDDLE_BLOCK]]:
 ; CHECK-NEXT:    [[TMP7:%.*]] = call i32 @llvm.vector.reduce.or.v4i32(<4 x i32> [[VEC_PHI6]])
-; CHECK-NEXT:    [[TMP8:%.*]] = call i1 @llvm.vector.reduce.or.v4i1(<4 x i1> splat (i1 true))
 ; CHECK-NEXT:    [[CMP_N9:%.*]] = icmp eq i64 [[TMP0]], [[N_VEC4]]
 ; CHECK-NEXT:    br i1 [[CMP_N9]], label %[[EXIT]], label %[[VEC_EPILOG_SCALAR_PH]]
 ; CHECK:       [[VEC_EPILOG_SCALAR_PH]]:
diff --git a/llvm/test/Transforms/LoopVectorize/select-cmp-blend-chain.ll b/llvm/test/Transforms/LoopVectorize/select-cmp-blend-chain.ll
index d6392a8b30dcb..8b12e09631246 100644
--- a/llvm/test/Transforms/LoopVectorize/select-cmp-blend-chain.ll
+++ b/llvm/test/Transforms/LoopVectorize/select-cmp-blend-chain.ll
@@ -26,7 +26,6 @@ define i32 @anyof_two_blend_chain(i1 %c0, i1 %c1, i32 %n) {
 ; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
 ; CHECK-NEXT:    br i1 [[TMP2]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
 ; CHECK:       [[MIDDLE_BLOCK]]:
-; CHECK-NEXT:    [[TMP3:%.*]] = call i1 @llvm.vector.reduce.or.v4i1(<4 x i1> [[PREDPHI1]])
 ; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i32 [[SMAX]], [[N_VEC]]
 ; CHECK-NEXT:    br i1 [[CMP_N]], label %[[EXIT:.*]], label %[[SCALAR_PH]]
 ; CHECK:       [[SCALAR_PH]]:
@@ -110,7 +109,6 @@ define i32 @anyof_three_blend_chain(i1 %c0, i1 %c1, i1 %c2, i32 %n) {
 ; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
 ; CHECK-NEXT:    br i1 [[TMP2]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP4:![0-9]+]]
 ; CHECK:       [[MIDDLE_BLOCK]]:
-; CHECK-NEXT:    [[TMP3:%.*]] = call i1 @llvm.vector.reduce.or.v4i1(<4 x i1> [[PREDPHI2]])
 ; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i32 [[SMAX]], [[N_VEC]]
 ; CHECK-NEXT:    br i1 [[CMP_N]], label %[[EXIT:.*]], label %[[SCALAR_PH]]
 ; CHECK:       [[SCALAR_PH]]:
@@ -209,7 +207,6 @@ define i32 @anyof_diamond_blend_chain(i1 %c0, i1 %c1, i32 %n) {
 ; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
 ; CHECK-NEXT:    br i1 [[TMP4]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP6:![0-9]+]]
 ; CHECK:       [[MIDDLE_BLOCK]]:
-; CHECK-NEXT:    [[TMP5:%.*]] = call i1 @llvm.vector.reduce.or.v4i1(<4 x i1> [[TMP3]])
 ; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i32 [[SMAX]], [[N_VEC]]
 ; CHECK-NEXT:    br i1 [[CMP_N]], label %[[EXIT:.*]], label %[[SCALAR_PH]]
 ; CHECK:       [[SCALAR_PH]]:
@@ -310,7 +307,6 @@ define i32 @anyof_blend_with_select_mask(i1 %a, i1 %b, i32 %n) {
 ; CHECK-NEXT:    [[TMP3:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
 ; CHECK-NEXT:    br i1 [[TMP3]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP8:![0-9]+]]
 ; CHECK:       [[MIDDLE_BLOCK]]:
-; CHECK-NEXT:    [[TMP4:%.*]] = call i1 @llvm.vector.reduce.or.v4i1(<4 x i1> [[PREDPHI]])
 ; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i32 [[SMAX]], [[N_VEC]]
 ; CHECK-NEXT:    br i1 [[CMP_N]], label %[[EXIT:.*]], label %[[SCALAR_PH]]
 ; CHECK:       [[SCALAR_PH]]:

``````````

</details>


https://github.com/llvm/llvm-project/pull/212982