[llvm] [VPlan] Convert BuildVector with all-equal values to Broadcast. (PR #165826)
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llvm-commits at lists.llvm.org
Thu Oct 30 21:46:21 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-vectorizers
Author: Florian Hahn (fhahn)
<details>
<summary>Changes</summary>
Fold BuildVector where all operands are equal to Broadcast of the first operand. This will subsequently make it easier to remove additional buildvectors/broadcasts, e.g. via
https://github.com/llvm/llvm-project/pull/165506.
---
Full diff: https://github.com/llvm/llvm-project/pull/165826.diff
5 Files Affected:
- (modified) llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp (+6)
- (modified) llvm/test/Transforms/LoopVectorize/AArch64/force-target-instruction-cost.ll (+2-2)
- (modified) llvm/test/Transforms/LoopVectorize/AArch64/licm-calls.ll (+2-2)
- (modified) llvm/test/Transforms/LoopVectorize/AArch64/masked-call-scalarize.ll (+9-9)
- (modified) llvm/test/Transforms/LoopVectorize/X86/replicate-recipe-with-only-first-lane-used.ll (+2-4)
``````````diff
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index 986c801abf684..d12588e2861d1 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -1282,6 +1282,12 @@ static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
return;
}
+ if (match(Def, m_BuildVector()) && all_equal(R.operands())) {
+ Def->replaceAllUsesWith(
+ Builder.createNaryOp(VPInstruction::Broadcast, Def->getOperand(0)));
+ return;
+ }
+
if (auto *Phi = dyn_cast<VPPhi>(Def)) {
if (Phi->getNumOperands() == 1)
Phi->replaceAllUsesWith(Phi->getOperand(0));
diff --git a/llvm/test/Transforms/LoopVectorize/AArch64/force-target-instruction-cost.ll b/llvm/test/Transforms/LoopVectorize/AArch64/force-target-instruction-cost.ll
index bfee39eac0ae2..068f82c7db670 100644
--- a/llvm/test/Transforms/LoopVectorize/AArch64/force-target-instruction-cost.ll
+++ b/llvm/test/Transforms/LoopVectorize/AArch64/force-target-instruction-cost.ll
@@ -365,8 +365,8 @@ define void @invalid_legacy_cost(i64 %N, ptr %x) #0 {
; CHECK: [[VECTOR_BODY]]:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP6:%.*]] = alloca i8, i64 0, align 16
-; CHECK-NEXT: [[TMP7:%.*]] = insertelement <2 x ptr> poison, ptr [[TMP6]], i32 0
-; CHECK-NEXT: [[TMP8:%.*]] = insertelement <2 x ptr> [[TMP7]], ptr [[TMP6]], i32 1
+; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <2 x ptr> poison, ptr [[TMP6]], i64 0
+; CHECK-NEXT: [[TMP8:%.*]] = shufflevector <2 x ptr> [[BROADCAST_SPLATINSERT]], <2 x ptr> poison, <2 x i32> zeroinitializer
; CHECK-NEXT: [[TMP9:%.*]] = getelementptr ptr, ptr [[X]], i64 [[INDEX]]
; CHECK-NEXT: store <2 x ptr> [[TMP8]], ptr [[TMP9]], align 8
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 2
diff --git a/llvm/test/Transforms/LoopVectorize/AArch64/licm-calls.ll b/llvm/test/Transforms/LoopVectorize/AArch64/licm-calls.ll
index ea0148952f51b..0a9494e4c7ade 100644
--- a/llvm/test/Transforms/LoopVectorize/AArch64/licm-calls.ll
+++ b/llvm/test/Transforms/LoopVectorize/AArch64/licm-calls.ll
@@ -10,8 +10,8 @@ define void @licm_replicate_call(double %x, ptr %dst) {
; CHECK-NEXT: br label %[[VECTOR_PH:.*]]
; CHECK: [[VECTOR_PH]]:
; CHECK-NEXT: [[TMP1:%.*]] = tail call double @llvm.pow.f64(double [[X]], double 3.000000e+00)
-; CHECK-NEXT: [[TMP2:%.*]] = insertelement <2 x double> poison, double [[TMP1]], i32 0
-; CHECK-NEXT: [[TMP3:%.*]] = insertelement <2 x double> [[TMP2]], double [[TMP1]], i32 1
+; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <2 x double> poison, double [[TMP1]], i64 0
+; CHECK-NEXT: [[TMP3:%.*]] = shufflevector <2 x double> [[BROADCAST_SPLATINSERT]], <2 x double> poison, <2 x i32> zeroinitializer
; CHECK-NEXT: br label %[[VECTOR_BODY:.*]]
; CHECK: [[VECTOR_BODY]]:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
diff --git a/llvm/test/Transforms/LoopVectorize/AArch64/masked-call-scalarize.ll b/llvm/test/Transforms/LoopVectorize/AArch64/masked-call-scalarize.ll
index 157b78704234a..35589573eed76 100644
--- a/llvm/test/Transforms/LoopVectorize/AArch64/masked-call-scalarize.ll
+++ b/llvm/test/Transforms/LoopVectorize/AArch64/masked-call-scalarize.ll
@@ -64,9 +64,9 @@ define void @test_widen_exp_v2(ptr noalias %p2, ptr noalias %p, i64 %n) #5 {
; TFCOMMON-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDEX_NEXT:%.*]], [[PRED_STORE_CONTINUE6:%.*]] ]
; TFCOMMON-NEXT: [[ACTIVE_LANE_MASK:%.*]] = phi <2 x i1> [ [[ACTIVE_LANE_MASK_ENTRY]], [[ENTRY]] ], [ [[ACTIVE_LANE_MASK_NEXT:%.*]], [[PRED_STORE_CONTINUE6]] ]
; TFCOMMON-NEXT: [[LD:%.*]] = load double, ptr [[P2:%.*]], align 8
-; TFCOMMON-NEXT: [[TMP5:%.*]] = tail call double @llvm.exp.f64(double [[LD]]) #[[ATTR3:[0-9]+]]
-; TFCOMMON-NEXT: [[TMP7:%.*]] = insertelement <2 x double> poison, double [[TMP5]], i32 0
-; TFCOMMON-NEXT: [[TMP8:%.*]] = insertelement <2 x double> [[TMP7]], double [[TMP5]], i32 1
+; TFCOMMON-NEXT: [[TMP5:%.*]] = tail call double @llvm.exp.f64(double [[LD]]) #[[ATTR2:[0-9]+]]
+; TFCOMMON-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <2 x double> poison, double [[TMP5]], i64 0
+; TFCOMMON-NEXT: [[TMP8:%.*]] = shufflevector <2 x double> [[BROADCAST_SPLATINSERT]], <2 x double> poison, <2 x i32> zeroinitializer
; TFCOMMON-NEXT: [[TMP9:%.*]] = fcmp ogt <2 x double> [[TMP8]], zeroinitializer
; TFCOMMON-NEXT: [[PREDPHI:%.*]] = select <2 x i1> [[TMP9]], <2 x double> zeroinitializer, <2 x double> splat (double 1.000000e+00)
; TFCOMMON-NEXT: [[TMP16:%.*]] = extractelement <2 x i1> [[ACTIVE_LANE_MASK]], i32 0
@@ -79,7 +79,7 @@ define void @test_widen_exp_v2(ptr noalias %p2, ptr noalias %p, i64 %n) #5 {
; TFCOMMON-NEXT: [[TMP14:%.*]] = extractelement <2 x i1> [[ACTIVE_LANE_MASK]], i32 1
; TFCOMMON-NEXT: br i1 [[TMP14]], label [[PRED_STORE_IF1:%.*]], label [[PRED_STORE_CONTINUE6]]
; TFCOMMON: pred.store.if1:
-; TFCOMMON-NEXT: [[TMP19:%.*]] = extractelement <2 x double> [[PREDPHI]], i32 1
+; TFCOMMON-NEXT: [[TMP19:%.*]] = extractelement <2 x double> [[PREDPHI]], i32 0
; TFCOMMON-NEXT: store double [[TMP19]], ptr [[P]], align 8
; TFCOMMON-NEXT: br label [[PRED_STORE_CONTINUE6]]
; TFCOMMON: pred.store.continue2:
@@ -105,9 +105,9 @@ define void @test_widen_exp_v2(ptr noalias %p2, ptr noalias %p, i64 %n) #5 {
; TFA_INTERLEAVE-NEXT: [[ACTIVE_LANE_MASK:%.*]] = phi <2 x i1> [ [[ACTIVE_LANE_MASK_ENTRY]], [[ENTRY]] ], [ [[ACTIVE_LANE_MASK_NEXT:%.*]], [[PRED_STORE_CONTINUE9]] ]
; TFA_INTERLEAVE-NEXT: [[ACTIVE_LANE_MASK2:%.*]] = phi <2 x i1> [ [[ACTIVE_LANE_MASK_ENTRY1]], [[ENTRY]] ], [ [[ACTIVE_LANE_MASK_NEXT10:%.*]], [[PRED_STORE_CONTINUE9]] ]
; TFA_INTERLEAVE-NEXT: [[TMP4:%.*]] = load double, ptr [[P2:%.*]], align 8
-; TFA_INTERLEAVE-NEXT: [[TMP9:%.*]] = tail call double @llvm.exp.f64(double [[TMP4]]) #[[ATTR3:[0-9]+]]
-; TFA_INTERLEAVE-NEXT: [[TMP11:%.*]] = insertelement <2 x double> poison, double [[TMP9]], i32 0
-; TFA_INTERLEAVE-NEXT: [[TMP12:%.*]] = insertelement <2 x double> [[TMP11]], double [[TMP9]], i32 1
+; TFA_INTERLEAVE-NEXT: [[TMP5:%.*]] = tail call double @llvm.exp.f64(double [[TMP4]]) #[[ATTR2:[0-9]+]]
+; TFA_INTERLEAVE-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <2 x double> poison, double [[TMP5]], i64 0
+; TFA_INTERLEAVE-NEXT: [[TMP12:%.*]] = shufflevector <2 x double> [[BROADCAST_SPLATINSERT]], <2 x double> poison, <2 x i32> zeroinitializer
; TFA_INTERLEAVE-NEXT: [[TMP14:%.*]] = fcmp ogt <2 x double> [[TMP12]], zeroinitializer
; TFA_INTERLEAVE-NEXT: [[PREDPHI3:%.*]] = select <2 x i1> [[TMP14]], <2 x double> zeroinitializer, <2 x double> splat (double 1.000000e+00)
; TFA_INTERLEAVE-NEXT: [[TMP19:%.*]] = extractelement <2 x i1> [[ACTIVE_LANE_MASK]], i32 0
@@ -120,7 +120,7 @@ define void @test_widen_exp_v2(ptr noalias %p2, ptr noalias %p, i64 %n) #5 {
; TFA_INTERLEAVE-NEXT: [[TMP29:%.*]] = extractelement <2 x i1> [[ACTIVE_LANE_MASK]], i32 1
; TFA_INTERLEAVE-NEXT: br i1 [[TMP29]], label [[PRED_STORE_IF4:%.*]], label [[PRED_STORE_CONTINUE5:%.*]]
; TFA_INTERLEAVE: pred.store.if3:
-; TFA_INTERLEAVE-NEXT: [[TMP22:%.*]] = extractelement <2 x double> [[PREDPHI3]], i32 1
+; TFA_INTERLEAVE-NEXT: [[TMP22:%.*]] = extractelement <2 x double> [[PREDPHI3]], i32 0
; TFA_INTERLEAVE-NEXT: store double [[TMP22]], ptr [[P]], align 8
; TFA_INTERLEAVE-NEXT: br label [[PRED_STORE_CONTINUE5]]
; TFA_INTERLEAVE: pred.store.continue4:
@@ -134,7 +134,7 @@ define void @test_widen_exp_v2(ptr noalias %p2, ptr noalias %p, i64 %n) #5 {
; TFA_INTERLEAVE-NEXT: [[TMP25:%.*]] = extractelement <2 x i1> [[ACTIVE_LANE_MASK2]], i32 1
; TFA_INTERLEAVE-NEXT: br i1 [[TMP25]], label [[PRED_STORE_IF8:%.*]], label [[PRED_STORE_CONTINUE9]]
; TFA_INTERLEAVE: pred.store.if7:
-; TFA_INTERLEAVE-NEXT: [[TMP34:%.*]] = extractelement <2 x double> [[PREDPHI3]], i32 1
+; TFA_INTERLEAVE-NEXT: [[TMP34:%.*]] = extractelement <2 x double> [[PREDPHI3]], i32 0
; TFA_INTERLEAVE-NEXT: store double [[TMP34]], ptr [[P]], align 8
; TFA_INTERLEAVE-NEXT: br label [[PRED_STORE_CONTINUE9]]
; TFA_INTERLEAVE: pred.store.continue8:
diff --git a/llvm/test/Transforms/LoopVectorize/X86/replicate-recipe-with-only-first-lane-used.ll b/llvm/test/Transforms/LoopVectorize/X86/replicate-recipe-with-only-first-lane-used.ll
index 03087bb883464..4590dfc5326b5 100644
--- a/llvm/test/Transforms/LoopVectorize/X86/replicate-recipe-with-only-first-lane-used.ll
+++ b/llvm/test/Transforms/LoopVectorize/X86/replicate-recipe-with-only-first-lane-used.ll
@@ -199,10 +199,8 @@ define float @uniform_load_replicating_select(ptr %A, ptr %B, i64 %1) {
; CHECK-NEXT: [[TMP5:%.*]] = add i64 [[INDEX]], 7
; CHECK-NEXT: [[TMP6:%.*]] = load float, ptr [[A]], align 4
; CHECK-NEXT: [[TMP10:%.*]] = fcmp ogt float [[TMP6]], 0.000000e+00
-; CHECK-NEXT: [[TMP8:%.*]] = insertelement <4 x i1> poison, i1 [[TMP10]], i32 0
-; CHECK-NEXT: [[TMP9:%.*]] = insertelement <4 x i1> [[TMP8]], i1 [[TMP10]], i32 1
-; CHECK-NEXT: [[TMP13:%.*]] = insertelement <4 x i1> [[TMP9]], i1 [[TMP10]], i32 2
-; CHECK-NEXT: [[TMP14:%.*]] = insertelement <4 x i1> [[TMP13]], i1 [[TMP10]], i32 3
+; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i1> poison, i1 [[TMP10]], i64 0
+; CHECK-NEXT: [[TMP14:%.*]] = shufflevector <4 x i1> [[BROADCAST_SPLATINSERT]], <4 x i1> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: [[TMP15:%.*]] = getelementptr inbounds float, ptr [[B]], i64 [[TMP2]]
; CHECK-NEXT: [[TMP16:%.*]] = getelementptr inbounds float, ptr [[B]], i64 [[TMP3]]
; CHECK-NEXT: [[TMP17:%.*]] = getelementptr inbounds float, ptr [[B]], i64 [[TMP4]]
``````````
</details>
https://github.com/llvm/llvm-project/pull/165826
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