[llvm] [SCEV] Disallow simplifying phi(undef, X) to X (PR #115109)

Yingwei Zheng via llvm-commits llvm-commits at lists.llvm.org
Wed Nov 6 06:17:59 PST 2024


https://github.com/dtcxzyw updated https://github.com/llvm/llvm-project/pull/115109

>From e33c8991cb99d76bd4ba7092db56152f41729eb1 Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Tue, 5 Nov 2024 21:43:10 +0800
Subject: [PATCH 1/3] [LoopFullUnroll] Add pre-commit tests. NFC.

---
 llvm/test/Transforms/LoopUnroll/pr114879.ll | 62 +++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 llvm/test/Transforms/LoopUnroll/pr114879.ll

diff --git a/llvm/test/Transforms/LoopUnroll/pr114879.ll b/llvm/test/Transforms/LoopUnroll/pr114879.ll
new file mode 100644
index 00000000000000..14ca9ceb40ac48
--- /dev/null
+++ b/llvm/test/Transforms/LoopUnroll/pr114879.ll
@@ -0,0 +1,62 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S -passes=loop-unroll-full -unroll-full-max-count=1 %s | FileCheck %s
+
+ at GlobIntONE = global i32 0, align 4
+
+; Make sure we don't reuse the phi (undef, X) for X.
+
+define ptr @test() {
+; CHECK-LABEL: define ptr @test() {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    br label %[[FOR_BODY_PEEL_BEGIN:.*]]
+; CHECK:       [[FOR_BODY_PEEL_BEGIN]]:
+; CHECK-NEXT:    br label %[[FOR_BODY_PEEL:.*]]
+; CHECK:       [[FOR_BODY_PEEL]]:
+; CHECK-NEXT:    br i1 true, label %[[CLEANUP_PEEL:.*]], label %[[CLEANUP_LOOPEXIT_PEEL:.*]]
+; CHECK:       [[CLEANUP_LOOPEXIT_PEEL]]:
+; CHECK-NEXT:    br label %[[CLEANUP_PEEL]]
+; CHECK:       [[CLEANUP_PEEL]]:
+; CHECK-NEXT:    [[RETVAL_2_PEEL:%.*]] = phi ptr [ undef, %[[FOR_BODY_PEEL]] ], [ @GlobIntONE, %[[CLEANUP_LOOPEXIT_PEEL]] ]
+; CHECK-NEXT:    br i1 true, label %[[FOR_BODY_PEEL_NEXT:.*]], label %[[CLEANUP2:.*]]
+; CHECK:       [[FOR_BODY_PEEL_NEXT]]:
+; CHECK-NEXT:    br label %[[FOR_BODY_PEEL_NEXT1:.*]]
+; CHECK:       [[FOR_BODY_PEEL_NEXT1]]:
+; CHECK-NEXT:    br label %[[ENTRY_PEEL_NEWPH:.*]]
+; CHECK:       [[ENTRY_PEEL_NEWPH]]:
+; CHECK-NEXT:    br label %[[FOR_BODY:.*]]
+; CHECK:       [[FOR_BODY]]:
+; CHECK-NEXT:    br i1 false, label %[[CLEANUP:.*]], label %[[CLEANUP_LOOPEXIT:.*]]
+; CHECK:       [[CLEANUP_LOOPEXIT]]:
+; CHECK-NEXT:    br label %[[CLEANUP]]
+; CHECK:       [[CLEANUP]]:
+; CHECK-NEXT:    br i1 false, label %[[FOR_BODY]], label %[[CLEANUP2_LOOPEXIT:.*]], !llvm.loop [[LOOP0:![0-9]+]]
+; CHECK:       [[CLEANUP2_LOOPEXIT]]:
+; CHECK-NEXT:    [[RETVAL_2_LCSSA_PH:%.*]] = phi ptr [ [[RETVAL_2_PEEL]], %[[CLEANUP]] ]
+; CHECK-NEXT:    br label %[[CLEANUP2]]
+; CHECK:       [[CLEANUP2]]:
+; CHECK-NEXT:    [[RETVAL_2_LCSSA:%.*]] = phi ptr [ [[RETVAL_2_PEEL]], %[[CLEANUP_PEEL]] ], [ [[RETVAL_2_LCSSA_PH]], %[[CLEANUP2_LOOPEXIT]] ]
+; CHECK-NEXT:    ret ptr [[RETVAL_2_LCSSA]]
+;
+entry:
+  br label %for.body
+
+for.body:
+  %retval.0 = phi ptr [ undef, %entry ], [ %retval.2, %cleanup ]
+  %cmp1.not = phi i1 [ true, %entry ], [ false, %cleanup ]
+  br i1 %cmp1.not, label %cleanup, label %cleanup.loopexit
+
+cleanup.loopexit:
+  br label %cleanup
+
+cleanup:
+  %retval.2 = phi ptr [ %retval.0, %for.body ], [ @GlobIntONE, %cleanup.loopexit ]
+  br i1 %cmp1.not, label %for.body, label %cleanup2
+
+cleanup2:
+  %retval.2.lcssa = phi ptr [ %retval.2, %cleanup ]
+  ret ptr %retval.2.lcssa
+}
+;.
+; CHECK: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]]}
+; CHECK: [[META1]] = !{!"llvm.loop.peeled.count", i32 1}
+;.

>From ae1539a7368c30d195b6e7c351b6124e5c91eae7 Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Wed, 6 Nov 2024 10:28:29 +0800
Subject: [PATCH 2/3] [SCEV] Disallow simplifying phi(undef, X) to X

---
 llvm/lib/Analysis/ScalarEvolution.cpp         |  6 ++-
 .../invalidate-modified-lcssa-phi.ll          |  3 +-
 .../IndVarSimplify/no-iv-rewrite.ll           |  6 ++-
 .../X86/2012-01-13-phielim.ll                 | 16 ++++----
 llvm/test/Transforms/LoopUnroll/pr114879.ll   |  2 +-
 .../Transforms/LoopVectorize/uniform-blend.ll | 41 +++++++++++++++----
 .../Analysis/ScalarEvolutionTest.cpp          |  2 +-
 7 files changed, 53 insertions(+), 23 deletions(-)

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 58e23e9556f144..b10811133770e1 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -6023,7 +6023,11 @@ const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
   if (const SCEV *S = createAddRecFromPHI(PN))
     return S;
 
-  if (Value *V = simplifyInstruction(PN, {getDataLayout(), &TLI, &DT, &AC}))
+  // We do not allow simplifying phi (undef, X) to X here, to avoid reusing the
+  // phi node for X.
+  if (Value *V = simplifyInstruction(
+          PN, {getDataLayout(), &TLI, &DT, &AC, /*CtxI=*/nullptr,
+               /*UseInstrInfo=*/true, /*CanUseUndef=*/false}))
     return getSCEV(V);
 
   if (const SCEV *S = createNodeFromSelectLikePHI(PN))
diff --git a/llvm/test/Transforms/IndVarSimplify/invalidate-modified-lcssa-phi.ll b/llvm/test/Transforms/IndVarSimplify/invalidate-modified-lcssa-phi.ll
index 856fc376204995..0538c1c64de34d 100644
--- a/llvm/test/Transforms/IndVarSimplify/invalidate-modified-lcssa-phi.ll
+++ b/llvm/test/Transforms/IndVarSimplify/invalidate-modified-lcssa-phi.ll
@@ -48,13 +48,14 @@ define i8 @test_pr52023(i1 %c.1, i1 %c.2) {
 ; CHECK-NEXT:    br label [[LOOP_1:%.*]]
 ; CHECK:       loop.1:
 ; CHECK-NEXT:    [[INC79:%.*]] = phi i8 [ [[TMP0:%.*]], [[LOOP_1_LATCH:%.*]] ], [ 0, [[ENTRY:%.*]] ]
-; CHECK-NEXT:    [[TMP0]] = add i8 [[INC79]], 1
+; CHECK-NEXT:    [[TMP1:%.*]] = add i8 [[INC79]], 1
 ; CHECK-NEXT:    br label [[LOOP_2:%.*]]
 ; CHECK:       loop.2:
 ; CHECK-NEXT:    br i1 [[C_1:%.*]], label [[LOOP_2_LATCH:%.*]], label [[LOOP_1_LATCH]]
 ; CHECK:       loop.2.latch:
 ; CHECK-NEXT:    br label [[LOOP_1_LATCH]]
 ; CHECK:       loop.1.latch:
+; CHECK-NEXT:    [[TMP0]] = phi i8 [ [[TMP1]], [[LOOP_2_LATCH]] ], [ undef, [[LOOP_2]] ]
 ; CHECK-NEXT:    br i1 [[C_2:%.*]], label [[EXIT:%.*]], label [[LOOP_1]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    [[INC_LCSSA_LCSSA:%.*]] = phi i8 [ [[TMP0]], [[LOOP_1_LATCH]] ]
diff --git a/llvm/test/Transforms/IndVarSimplify/no-iv-rewrite.ll b/llvm/test/Transforms/IndVarSimplify/no-iv-rewrite.ll
index 579b8536cedf03..5339468fe8036b 100644
--- a/llvm/test/Transforms/IndVarSimplify/no-iv-rewrite.ll
+++ b/llvm/test/Transforms/IndVarSimplify/no-iv-rewrite.ll
@@ -260,11 +260,13 @@ define void @identityphi(i32 %limit) nounwind {
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
-; CHECK-NEXT:    br i1 undef, label [[IF_THEN:%.*]], label [[CONTROL:%.*]]
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[CONTROL:%.*]] ]
+; CHECK-NEXT:    br i1 undef, label [[IF_THEN:%.*]], label [[CONTROL]]
 ; CHECK:       if.then:
 ; CHECK-NEXT:    br label [[CONTROL]]
 ; CHECK:       control:
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 0, [[LIMIT:%.*]]
+; CHECK-NEXT:    [[IV_NEXT]] = phi i32 [ [[IV]], [[LOOP]] ], [ undef, [[IF_THEN]] ]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[IV_NEXT]], [[LIMIT:%.*]]
 ; CHECK-NEXT:    br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    ret void
diff --git a/llvm/test/Transforms/LoopStrengthReduce/X86/2012-01-13-phielim.ll b/llvm/test/Transforms/LoopStrengthReduce/X86/2012-01-13-phielim.ll
index 492746615d8461..38f18f68e2db72 100644
--- a/llvm/test/Transforms/LoopStrengthReduce/X86/2012-01-13-phielim.ll
+++ b/llvm/test/Transforms/LoopStrengthReduce/X86/2012-01-13-phielim.ll
@@ -156,29 +156,29 @@ define fastcc void @test3(ptr nocapture %u) nounwind uwtable ssp {
 ; CHECK:       for.inc8.us.i:
 ; CHECK-NEXT:    br i1 true, label [[MESHBB1_LOOPEXIT:%.*]], label [[MESHBB:%.*]]
 ; CHECK:       for.body3.us.i:
-; CHECK-NEXT:    [[INDVARS_IV_I_SV_PHI:%.*]] = phi i64 [ [[INDVARS_IV_NEXT_I:%.*]], [[MESHBB]] ], [ 0, [[FOR_BODY3_LR_PH_US_I:%.*]] ]
+; CHECK-NEXT:    [[TMP:%.*]] = phi i32 [ [[LSR_IV_NEXT:%.*]], [[MESHBB]] ], [ [[TMP3:%.*]], [[FOR_BODY3_LR_PH_US_I:%.*]] ]
+; CHECK-NEXT:    [[SCEVGEP:%.*]] = phi ptr [ [[SCEVGEP1:%.*]], [[MESHBB]] ], [ [[U:%.*]], [[FOR_BODY3_LR_PH_US_I]] ]
 ; CHECK-NEXT:    [[OPQ_SA_CALC12:%.*]] = sub i32 undef, 227
-; CHECK-NEXT:    [[TMP0:%.*]] = add i64 [[LSR_IV:%.*]], [[INDVARS_IV_I_SV_PHI]]
-; CHECK-NEXT:    [[TMP:%.*]] = trunc i64 [[TMP0]] to i32
 ; CHECK-NEXT:    [[MUL_I_US_I:%.*]] = mul nsw i32 0, [[TMP]]
-; CHECK-NEXT:    [[TMP1:%.*]] = shl nuw nsw i64 [[INDVARS_IV_I_SV_PHI]], 3
-; CHECK-NEXT:    [[SCEVGEP:%.*]] = getelementptr i8, ptr [[U:%.*]], i64 [[TMP1]]
 ; CHECK-NEXT:    [[TMP2:%.*]] = load double, ptr [[SCEVGEP]], align 8
 ; CHECK-NEXT:    br i1 undef, label [[FOR_INC8_US_I:%.*]], label [[MESHBB]]
 ; CHECK:       for.body3.lr.ph.us.i.loopexit:
-; CHECK-NEXT:    [[LSR_IV_NEXT:%.*]] = add i64 [[LSR_IV]], 1
 ; CHECK-NEXT:    br label [[FOR_BODY3_LR_PH_US_I]]
 ; CHECK:       for.body3.lr.ph.us.i:
-; CHECK-NEXT:    [[LSR_IV]] = phi i64 [ [[LSR_IV_NEXT]], [[FOR_BODY3_LR_PH_US_I_LOOPEXIT:%.*]] ], [ undef, [[MESHBB1]] ]
+; CHECK-NEXT:    [[LSR_IV:%.*]] = phi i64 [ undef, [[MESHBB1]] ], [ [[INDVARS_IV8_I_SV_PHI24:%.*]], [[FOR_BODY3_LR_PH_US_I_LOOPEXIT:%.*]] ]
 ; CHECK-NEXT:    [[ARRAYIDX_US_I:%.*]] = getelementptr inbounds double, ptr undef, i64 [[LSR_IV]]
+; CHECK-NEXT:    [[TMP1:%.*]] = add i64 [[LSR_IV]], 1
+; CHECK-NEXT:    [[TMP3]] = trunc i64 [[LSR_IV]] to i32
 ; CHECK-NEXT:    br label [[FOR_BODY3_US_I:%.*]]
 ; CHECK:       for.inc8.us.i2:
 ; CHECK-NEXT:    unreachable
 ; CHECK:       eval_At_times_u.exit:
 ; CHECK-NEXT:    ret void
 ; CHECK:       meshBB:
+; CHECK-NEXT:    [[INDVARS_IV8_I_SV_PHI24]] = phi i64 [ undef, [[FOR_BODY3_US_I]] ], [ [[TMP1]], [[FOR_INC8_US_I]] ]
 ; CHECK-NEXT:    [[MESHSTACKVARIABLE_PHI:%.*]] = phi i32 [ [[OPQ_SA_CALC12]], [[FOR_BODY3_US_I]] ], [ undef, [[FOR_INC8_US_I]] ]
-; CHECK-NEXT:    [[INDVARS_IV_NEXT_I]] = add i64 [[INDVARS_IV_I_SV_PHI]], 1
+; CHECK-NEXT:    [[SCEVGEP1]] = getelementptr i8, ptr [[SCEVGEP]], i64 8
+; CHECK-NEXT:    [[LSR_IV_NEXT]] = add i32 [[TMP]], 1
 ; CHECK-NEXT:    br i1 true, label [[FOR_BODY3_LR_PH_US_I_LOOPEXIT]], label [[FOR_BODY3_US_I]]
 ; CHECK:       meshBB1.loopexit:
 ; CHECK-NEXT:    br label [[MESHBB1]]
diff --git a/llvm/test/Transforms/LoopUnroll/pr114879.ll b/llvm/test/Transforms/LoopUnroll/pr114879.ll
index 14ca9ceb40ac48..4cd91a0f6c09f7 100644
--- a/llvm/test/Transforms/LoopUnroll/pr114879.ll
+++ b/llvm/test/Transforms/LoopUnroll/pr114879.ll
@@ -31,7 +31,7 @@ define ptr @test() {
 ; CHECK:       [[CLEANUP]]:
 ; CHECK-NEXT:    br i1 false, label %[[FOR_BODY]], label %[[CLEANUP2_LOOPEXIT:.*]], !llvm.loop [[LOOP0:![0-9]+]]
 ; CHECK:       [[CLEANUP2_LOOPEXIT]]:
-; CHECK-NEXT:    [[RETVAL_2_LCSSA_PH:%.*]] = phi ptr [ [[RETVAL_2_PEEL]], %[[CLEANUP]] ]
+; CHECK-NEXT:    [[RETVAL_2_LCSSA_PH:%.*]] = phi ptr [ @GlobIntONE, %[[CLEANUP]] ]
 ; CHECK-NEXT:    br label %[[CLEANUP2]]
 ; CHECK:       [[CLEANUP2]]:
 ; CHECK-NEXT:    [[RETVAL_2_LCSSA:%.*]] = phi ptr [ [[RETVAL_2_PEEL]], %[[CLEANUP_PEEL]] ], [ [[RETVAL_2_LCSSA_PH]], %[[CLEANUP2_LOOPEXIT]] ]
diff --git a/llvm/test/Transforms/LoopVectorize/uniform-blend.ll b/llvm/test/Transforms/LoopVectorize/uniform-blend.ll
index c9fc8beb006d9b..05919cdcf93c8c 100644
--- a/llvm/test/Transforms/LoopVectorize/uniform-blend.ll
+++ b/llvm/test/Transforms/LoopVectorize/uniform-blend.ll
@@ -9,16 +9,27 @@ define void @blend_uniform_iv_trunc(i1 %c) {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
 ; CHECK-NEXT:    br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
 ; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i1> poison, i1 [[C]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i1> [[BROADCAST_SPLATINSERT]], <4 x i1> poison, <4 x i32> zeroinitializer
 ; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
 ; CHECK:       [[VECTOR_BODY]]:
 ; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
-; CHECK-NEXT:    [[TMP0:%.*]] = trunc i64 [[INDEX]] to i16
-; CHECK-NEXT:    [[TMP1:%.*]] = add i16 [[TMP0]], 0
-; CHECK-NEXT:    [[PREDPHI:%.*]] = select i1 [[C]], i16 [[TMP1]], i16 undef
+; CHECK-NEXT:    [[VEC_IND:%.*]] = phi <4 x i16> [ <i16 0, i16 1, i16 2, i16 3>, %[[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[PREDPHI1:%.*]] = select <4 x i1> [[BROADCAST_SPLAT]], <4 x i16> [[VEC_IND]], <4 x i16> undef
+; CHECK-NEXT:    [[PREDPHI:%.*]] = extractelement <4 x i16> [[PREDPHI1]], i32 0
 ; CHECK-NEXT:    [[TMP2:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i16 [[PREDPHI]]
-; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds i16, ptr [[TMP2]], i32 0
-; CHECK-NEXT:    store <4 x i16> zeroinitializer, ptr [[TMP3]], align 2
+; CHECK-NEXT:    [[TMP8:%.*]] = extractelement <4 x i16> [[PREDPHI1]], i32 1
+; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i16 [[TMP8]]
+; CHECK-NEXT:    [[TMP9:%.*]] = extractelement <4 x i16> [[PREDPHI1]], i32 2
+; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i16 [[TMP9]]
+; CHECK-NEXT:    [[TMP6:%.*]] = extractelement <4 x i16> [[PREDPHI1]], i32 3
+; CHECK-NEXT:    [[TMP7:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i16 [[TMP6]]
+; CHECK-NEXT:    store i16 0, ptr [[TMP2]], align 2
+; CHECK-NEXT:    store i16 0, ptr [[TMP3]], align 2
+; CHECK-NEXT:    store i16 0, ptr [[TMP5]], align 2
+; CHECK-NEXT:    store i16 0, ptr [[TMP7]], align 2
 ; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
+; CHECK-NEXT:    [[VEC_IND_NEXT]] = add <4 x i16> [[VEC_IND]], <i16 4, i16 4, i16 4, i16 4>
 ; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i64 [[INDEX_NEXT]], 32
 ; CHECK-NEXT:    br i1 [[TMP4]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
 ; CHECK:       [[MIDDLE_BLOCK]]:
@@ -71,15 +82,27 @@ define void @blend_uniform_iv(i1 %c) {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
 ; CHECK-NEXT:    br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
 ; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i1> poison, i1 [[C]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i1> [[BROADCAST_SPLATINSERT]], <4 x i1> poison, <4 x i32> zeroinitializer
 ; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
 ; CHECK:       [[VECTOR_BODY]]:
 ; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
-; CHECK-NEXT:    [[TMP0:%.*]] = add i64 [[INDEX]], 0
-; CHECK-NEXT:    [[PREDPHI:%.*]] = select i1 [[C]], i64 [[TMP0]], i64 undef
+; CHECK-NEXT:    [[VEC_IND:%.*]] = phi <4 x i64> [ <i64 0, i64 1, i64 2, i64 3>, %[[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[PREDPHI1:%.*]] = select <4 x i1> [[BROADCAST_SPLAT]], <4 x i64> [[VEC_IND]], <4 x i64> undef
+; CHECK-NEXT:    [[PREDPHI:%.*]] = extractelement <4 x i64> [[PREDPHI1]], i32 0
 ; CHECK-NEXT:    [[TMP1:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[PREDPHI]]
-; CHECK-NEXT:    [[TMP2:%.*]] = getelementptr inbounds i16, ptr [[TMP1]], i32 0
-; CHECK-NEXT:    store <4 x i16> zeroinitializer, ptr [[TMP2]], align 2
+; CHECK-NEXT:    [[TMP2:%.*]] = extractelement <4 x i64> [[PREDPHI1]], i32 1
+; CHECK-NEXT:    [[TMP8:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[TMP2]]
+; CHECK-NEXT:    [[TMP4:%.*]] = extractelement <4 x i64> [[PREDPHI1]], i32 2
+; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[TMP4]]
+; CHECK-NEXT:    [[TMP6:%.*]] = extractelement <4 x i64> [[PREDPHI1]], i32 3
+; CHECK-NEXT:    [[TMP7:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[TMP6]]
+; CHECK-NEXT:    store i16 0, ptr [[TMP1]], align 2
+; CHECK-NEXT:    store i16 0, ptr [[TMP8]], align 2
+; CHECK-NEXT:    store i16 0, ptr [[TMP5]], align 2
+; CHECK-NEXT:    store i16 0, ptr [[TMP7]], align 2
 ; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
+; CHECK-NEXT:    [[VEC_IND_NEXT]] = add <4 x i64> [[VEC_IND]], <i64 4, i64 4, i64 4, i64 4>
 ; CHECK-NEXT:    [[TMP3:%.*]] = icmp eq i64 [[INDEX_NEXT]], 32
 ; CHECK-NEXT:    br i1 [[TMP3]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP4:![0-9]+]]
 ; CHECK:       [[MIDDLE_BLOCK]]:
diff --git a/llvm/unittests/Analysis/ScalarEvolutionTest.cpp b/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
index 37c61e4e4fa714..3450302f36f617 100644
--- a/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
+++ b/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
@@ -139,7 +139,7 @@ TEST_F(ScalarEvolutionsTest, SimplifiedPHI) {
   auto *Ty = Type::getInt32Ty(Context);
   auto *PN = PHINode::Create(Ty, 2, "", LoopBB->begin());
   PN->addIncoming(Constant::getNullValue(Ty), EntryBB);
-  PN->addIncoming(UndefValue::get(Ty), LoopBB);
+  PN->addIncoming(PoisonValue::get(Ty), LoopBB);
   ScalarEvolution SE = buildSE(*F);
   const SCEV *S1 = SE.getSCEV(PN);
   const SCEV *S2 = SE.getSCEV(PN);

>From 25d9d7f481a8c109bf1e83b8b0ef6acc405e6b6b Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Wed, 6 Nov 2024 22:17:40 +0800
Subject: [PATCH 3/3] [LoopVectorize] Address review comments. NFC.

---
 .../Transforms/LoopVectorize/uniform-blend.ll | 49 +++++--------------
 1 file changed, 13 insertions(+), 36 deletions(-)

diff --git a/llvm/test/Transforms/LoopVectorize/uniform-blend.ll b/llvm/test/Transforms/LoopVectorize/uniform-blend.ll
index 05919cdcf93c8c..ecc1ae817b6874 100644
--- a/llvm/test/Transforms/LoopVectorize/uniform-blend.ll
+++ b/llvm/test/Transforms/LoopVectorize/uniform-blend.ll
@@ -9,27 +9,16 @@ define void @blend_uniform_iv_trunc(i1 %c) {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
 ; CHECK-NEXT:    br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
 ; CHECK:       [[VECTOR_PH]]:
-; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i1> poison, i1 [[C]], i64 0
-; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i1> [[BROADCAST_SPLATINSERT]], <4 x i1> poison, <4 x i32> zeroinitializer
 ; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
 ; CHECK:       [[VECTOR_BODY]]:
 ; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
-; CHECK-NEXT:    [[VEC_IND:%.*]] = phi <4 x i16> [ <i16 0, i16 1, i16 2, i16 3>, %[[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[VECTOR_BODY]] ]
-; CHECK-NEXT:    [[PREDPHI1:%.*]] = select <4 x i1> [[BROADCAST_SPLAT]], <4 x i16> [[VEC_IND]], <4 x i16> undef
-; CHECK-NEXT:    [[PREDPHI:%.*]] = extractelement <4 x i16> [[PREDPHI1]], i32 0
-; CHECK-NEXT:    [[TMP2:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i16 [[PREDPHI]]
-; CHECK-NEXT:    [[TMP8:%.*]] = extractelement <4 x i16> [[PREDPHI1]], i32 1
-; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i16 [[TMP8]]
-; CHECK-NEXT:    [[TMP9:%.*]] = extractelement <4 x i16> [[PREDPHI1]], i32 2
-; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i16 [[TMP9]]
-; CHECK-NEXT:    [[TMP6:%.*]] = extractelement <4 x i16> [[PREDPHI1]], i32 3
+; CHECK-NEXT:    [[TMP0:%.*]] = trunc i64 [[INDEX]] to i16
+; CHECK-NEXT:    [[TMP1:%.*]] = add i16 [[TMP0]], 0
+; CHECK-NEXT:    [[TMP6:%.*]] = select i1 [[C]], i16 [[TMP1]], i16 poison
 ; CHECK-NEXT:    [[TMP7:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i16 [[TMP6]]
-; CHECK-NEXT:    store i16 0, ptr [[TMP2]], align 2
-; CHECK-NEXT:    store i16 0, ptr [[TMP3]], align 2
-; CHECK-NEXT:    store i16 0, ptr [[TMP5]], align 2
-; CHECK-NEXT:    store i16 0, ptr [[TMP7]], align 2
+; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds i16, ptr [[TMP7]], i32 0
+; CHECK-NEXT:    store <4 x i16> zeroinitializer, ptr [[TMP3]], align 2
 ; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
-; CHECK-NEXT:    [[VEC_IND_NEXT]] = add <4 x i16> [[VEC_IND]], <i16 4, i16 4, i16 4, i16 4>
 ; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i64 [[INDEX_NEXT]], 32
 ; CHECK-NEXT:    br i1 [[TMP4]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
 ; CHECK:       [[MIDDLE_BLOCK]]:
@@ -44,7 +33,7 @@ define void @blend_uniform_iv_trunc(i1 %c) {
 ; CHECK:       [[LOOP_NEXT]]:
 ; CHECK-NEXT:    br label %[[LOOP_LATCH]]
 ; CHECK:       [[LOOP_LATCH]]:
-; CHECK-NEXT:    [[BLEND:%.*]] = phi i16 [ undef, %[[LOOP_HEADER]] ], [ [[IV_TRUNC_2]], %[[LOOP_NEXT]] ]
+; CHECK-NEXT:    [[BLEND:%.*]] = phi i16 [ poison, %[[LOOP_HEADER]] ], [ [[IV_TRUNC_2]], %[[LOOP_NEXT]] ]
 ; CHECK-NEXT:    [[DST_PTR:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i16 [[BLEND]]
 ; CHECK-NEXT:    store i16 0, ptr [[DST_PTR]], align 2
 ; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
@@ -65,7 +54,7 @@ loop.next:                                        ; preds = %loop.header
   br label %loop.latch
 
 loop.latch:                                       ; preds = %loop.next, %loop.header
-  %blend = phi i16 [ undef, %loop.header ], [ %iv.trunc.2, %loop.next ]
+  %blend = phi i16 [ poison, %loop.header ], [ %iv.trunc.2, %loop.next ]
   %dst.ptr = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i16 %blend
   store i16 0, ptr %dst.ptr
   %iv.next = add nuw nsw i64 %iv, 1
@@ -82,27 +71,15 @@ define void @blend_uniform_iv(i1 %c) {
 ; CHECK-NEXT:  [[ENTRY:.*]]:
 ; CHECK-NEXT:    br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
 ; CHECK:       [[VECTOR_PH]]:
-; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i1> poison, i1 [[C]], i64 0
-; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i1> [[BROADCAST_SPLATINSERT]], <4 x i1> poison, <4 x i32> zeroinitializer
 ; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
 ; CHECK:       [[VECTOR_BODY]]:
 ; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
-; CHECK-NEXT:    [[VEC_IND:%.*]] = phi <4 x i64> [ <i64 0, i64 1, i64 2, i64 3>, %[[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[VECTOR_BODY]] ]
-; CHECK-NEXT:    [[PREDPHI1:%.*]] = select <4 x i1> [[BROADCAST_SPLAT]], <4 x i64> [[VEC_IND]], <4 x i64> undef
-; CHECK-NEXT:    [[PREDPHI:%.*]] = extractelement <4 x i64> [[PREDPHI1]], i32 0
-; CHECK-NEXT:    [[TMP1:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[PREDPHI]]
-; CHECK-NEXT:    [[TMP2:%.*]] = extractelement <4 x i64> [[PREDPHI1]], i32 1
-; CHECK-NEXT:    [[TMP8:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[TMP2]]
-; CHECK-NEXT:    [[TMP4:%.*]] = extractelement <4 x i64> [[PREDPHI1]], i32 2
-; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[TMP4]]
-; CHECK-NEXT:    [[TMP6:%.*]] = extractelement <4 x i64> [[PREDPHI1]], i32 3
+; CHECK-NEXT:    [[TMP0:%.*]] = add i64 [[INDEX]], 0
+; CHECK-NEXT:    [[TMP6:%.*]] = select i1 [[C]], i64 [[TMP0]], i64 poison
 ; CHECK-NEXT:    [[TMP7:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[TMP6]]
-; CHECK-NEXT:    store i16 0, ptr [[TMP1]], align 2
-; CHECK-NEXT:    store i16 0, ptr [[TMP8]], align 2
-; CHECK-NEXT:    store i16 0, ptr [[TMP5]], align 2
-; CHECK-NEXT:    store i16 0, ptr [[TMP7]], align 2
+; CHECK-NEXT:    [[TMP2:%.*]] = getelementptr inbounds i16, ptr [[TMP7]], i32 0
+; CHECK-NEXT:    store <4 x i16> zeroinitializer, ptr [[TMP2]], align 2
 ; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
-; CHECK-NEXT:    [[VEC_IND_NEXT]] = add <4 x i64> [[VEC_IND]], <i64 4, i64 4, i64 4, i64 4>
 ; CHECK-NEXT:    [[TMP3:%.*]] = icmp eq i64 [[INDEX_NEXT]], 32
 ; CHECK-NEXT:    br i1 [[TMP3]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP4:![0-9]+]]
 ; CHECK:       [[MIDDLE_BLOCK]]:
@@ -116,7 +93,7 @@ define void @blend_uniform_iv(i1 %c) {
 ; CHECK:       [[LOOP_NEXT]]:
 ; CHECK-NEXT:    br label %[[LOOP_LATCH]]
 ; CHECK:       [[LOOP_LATCH]]:
-; CHECK-NEXT:    [[BLEND:%.*]] = phi i64 [ undef, %[[LOOP_HEADER]] ], [ [[IV]], %[[LOOP_NEXT]] ]
+; CHECK-NEXT:    [[BLEND:%.*]] = phi i64 [ poison, %[[LOOP_HEADER]] ], [ [[IV]], %[[LOOP_NEXT]] ]
 ; CHECK-NEXT:    [[DST_PTR:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[BLEND]]
 ; CHECK-NEXT:    store i16 0, ptr [[DST_PTR]], align 2
 ; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
@@ -137,7 +114,7 @@ loop.next:                                        ; preds = %loop.header
   br label %loop.latch
 
 loop.latch:                                       ; preds = %loop.next, %loop.header
-  %blend = phi i64 [ undef, %loop.header ], [ %iv, %loop.next ]
+  %blend = phi i64 [ poison, %loop.header ], [ %iv, %loop.next ]
   %dst.ptr = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 %blend
   store i16 0, ptr %dst.ptr
   %iv.next = add nuw nsw i64 %iv, 1



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