[llvm] [VPlan] Simplify (x && y) || (x && z) -> x && (y || z) (PR #156308)

[Luke Lau via llvm-commits]

https://github.com/lukel97 created https://github.com/llvm/llvm-project/pull/156308

Split off from #155383, since it turns out this has a diff on its own.




>From fb5a33fb882f40e1154039e8879cc0c618e3a295 Mon Sep 17 00:00:00 2001
From: Luke Lau <luke at igalia.com>
Date: Tue, 26 Aug 2025 16:33:22 +0800
Subject: [PATCH] [VPlan] Simplify (x && y) || (x && z) -> x && (y || z)

---
 llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp | 15 +++++++++++++--
 .../LoopVectorize/RISCV/dead-ops-cost.ll          |  9 +--------
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index 17b54f2ef9c05..fc9bb806895c6 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -1068,7 +1068,7 @@ static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
   // TODO: Split up into simpler, modular combines: (X && Y) || (X && Z) into X
   // && (Y || Z) and (X || !X) into true. This requires queuing newly created
   // recipes to be visited during simplification.
-  VPValue *X, *Y;
+  VPValue *X, *Y, *Z;
   if (match(Def,
             m_c_BinaryOr(m_LogicalAnd(m_VPValue(X), m_VPValue(Y)),
                          m_LogicalAnd(m_Deferred(X), m_Not(m_Deferred(Y)))))) {
@@ -1092,6 +1092,17 @@ static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
     return;
   }
 
+  // (x && y) || (x && z) -> x && (y || z)
+  VPBuilder Builder(Def);
+  if (match(Def, m_c_BinaryOr(m_LogicalAnd(m_VPValue(X), m_VPValue(Y)),
+                              m_LogicalAnd(m_Deferred(X), m_VPValue(Z)))) &&
+      // Simplify only if one of the operands has one use to avoid creating an
+      // extra recipe.
+      (!Def->getOperand(0)->hasMoreThanOneUniqueUser() ||
+       !Def->getOperand(1)->hasMoreThanOneUniqueUser()))
+    return Def->replaceAllUsesWith(
+        Builder.createLogicalAnd(X, Builder.createOr(Y, Z)));
+
   if (match(Def, m_Select(m_VPValue(), m_VPValue(X), m_Deferred(X))))
     return Def->replaceAllUsesWith(X);
 
@@ -1158,7 +1169,7 @@ static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
                      m_VPValue(X), m_SpecificInt(1)))) {
     Type *WideStepTy = TypeInfo.inferScalarType(Def);
     if (TypeInfo.inferScalarType(X) != WideStepTy)
-      X = VPBuilder(Def).createWidenCast(Instruction::Trunc, X, WideStepTy);
+      X = Builder.createWidenCast(Instruction::Trunc, X, WideStepTy);
     Def->replaceAllUsesWith(X);
     return;
   }
diff --git a/llvm/test/Transforms/LoopVectorize/RISCV/dead-ops-cost.ll b/llvm/test/Transforms/LoopVectorize/RISCV/dead-ops-cost.ll
index a94187383a014..6b7d0a994a29d 100644
--- a/llvm/test/Transforms/LoopVectorize/RISCV/dead-ops-cost.ll
+++ b/llvm/test/Transforms/LoopVectorize/RISCV/dead-ops-cost.ll
@@ -315,19 +315,12 @@ define void @test_phi_in_latch_redundant(ptr %dst, i32 %a) {
 ; CHECK-NEXT:    [[VEC_IND:%.*]] = phi <vscale x 4 x i64> [ [[INDUCTION]], %[[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[VECTOR_BODY]] ]
 ; CHECK-NEXT:    [[AVL:%.*]] = phi i64 [ 37, %[[VECTOR_PH]] ], [ [[AVL_NEXT:%.*]], %[[VECTOR_BODY]] ]
 ; CHECK-NEXT:    [[TMP8:%.*]] = call i32 @llvm.experimental.get.vector.length.i64(i64 [[AVL]], i32 4, i1 true)
-; CHECK-NEXT:    [[BROADCAST_SPLATINSERT3:%.*]] = insertelement <vscale x 4 x i32> poison, i32 [[TMP8]], i64 0
-; CHECK-NEXT:    [[BROADCAST_SPLAT4:%.*]] = shufflevector <vscale x 4 x i32> [[BROADCAST_SPLATINSERT3]], <vscale x 4 x i32> poison, <vscale x 4 x i32> zeroinitializer
 ; CHECK-NEXT:    [[TMP5:%.*]] = zext i32 [[TMP8]] to i64
 ; CHECK-NEXT:    [[TMP9:%.*]] = mul i64 9, [[TMP5]]
 ; CHECK-NEXT:    [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <vscale x 4 x i64> poison, i64 [[TMP9]], i64 0
 ; CHECK-NEXT:    [[BROADCAST_SPLAT2:%.*]] = shufflevector <vscale x 4 x i64> [[BROADCAST_SPLATINSERT1]], <vscale x 4 x i64> poison, <vscale x 4 x i32> zeroinitializer
-; CHECK-NEXT:    [[TMP11:%.*]] = call <vscale x 4 x i32> @llvm.stepvector.nxv4i32()
-; CHECK-NEXT:    [[TMP12:%.*]] = icmp ult <vscale x 4 x i32> [[TMP11]], [[BROADCAST_SPLAT4]]
-; CHECK-NEXT:    [[TMP13:%.*]] = select <vscale x 4 x i1> [[TMP12]], <vscale x 4 x i1> splat (i1 true), <vscale x 4 x i1> zeroinitializer
-; CHECK-NEXT:    [[TMP14:%.*]] = select <vscale x 4 x i1> [[TMP12]], <vscale x 4 x i1> zeroinitializer, <vscale x 4 x i1> zeroinitializer
-; CHECK-NEXT:    [[TMP15:%.*]] = or <vscale x 4 x i1> [[TMP13]], [[TMP14]]
 ; CHECK-NEXT:    [[TMP16:%.*]] = getelementptr i32, ptr [[DST]], <vscale x 4 x i64> [[VEC_IND]]
-; CHECK-NEXT:    call void @llvm.vp.scatter.nxv4i32.nxv4p0(<vscale x 4 x i32> [[TMP19]], <vscale x 4 x ptr> align 4 [[TMP16]], <vscale x 4 x i1> [[TMP15]], i32 [[TMP8]])
+; CHECK-NEXT:    call void @llvm.vp.scatter.nxv4i32.nxv4p0(<vscale x 4 x i32> [[TMP19]], <vscale x 4 x ptr> align 4 [[TMP16]], <vscale x 4 x i1> splat (i1 true), i32 [[TMP8]])
 ; CHECK-NEXT:    [[TMP17:%.*]] = zext i32 [[TMP8]] to i64
 ; CHECK-NEXT:    [[AVL_NEXT]] = sub nuw i64 [[AVL]], [[TMP17]]
 ; CHECK-NEXT:    [[VEC_IND_NEXT]] = add <vscale x 4 x i64> [[VEC_IND]], [[BROADCAST_SPLAT2]]