[PATCH] D126895: [SLP] Phi inputs that come from an unreachable block should be undef.

[Vasileios Porpodas via Phabricator via llvm-commits]

vporpo updated this revision to Diff 433848.
vporpo added a comment.

If the input is undef keep it, else create a poison value.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D126895/new/

https://reviews.llvm.org/D126895

Files:
  llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
  llvm/test/Transforms/SLPVectorizer/X86/malformed_phis.ll
  llvm/test/Transforms/SLPVectorizer/X86/phi-unreachable-input-block.ll


Index: llvm/test/Transforms/SLPVectorizer/X86/phi-unreachable-input-block.ll
===================================================================
--- llvm/test/Transforms/SLPVectorizer/X86/phi-unreachable-input-block.ll
+++ llvm/test/Transforms/SLPVectorizer/X86/phi-unreachable-input-block.ll
@@ -15,7 +15,7 @@
 ; CHECK:       bb2:
 ; CHECK-NEXT:    br label [[BB3]]
 ; CHECK:       bb3:
-; CHECK-NEXT:    [[TMP2:%.*]] = phi <2 x i8> [ [[TMP1]], [[BB1:%.*]] ], [ poison, [[BB2:%.*]] ]
+; CHECK-NEXT:    [[TMP2:%.*]] = phi <2 x i8> [ [[TMP1]], [[BB1:%.*]] ], [ <i8 undef, i8 0>, [[BB2:%.*]] ]
 ; CHECK-NEXT:    [[TMP3:%.*]] = zext <2 x i8> [[TMP2]] to <2 x i64>
 ; CHECK-NEXT:    [[GEP0:%.*]] = getelementptr i64, i64* [[PTR:%.*]], i64 0
 ; CHECK-NEXT:    [[TMP4:%.*]] = bitcast i64* [[GEP0]] to <2 x i64>*
Index: llvm/test/Transforms/SLPVectorizer/X86/malformed_phis.ll
===================================================================
--- llvm/test/Transforms/SLPVectorizer/X86/malformed_phis.ll
+++ llvm/test/Transforms/SLPVectorizer/X86/malformed_phis.ll
@@ -116,7 +116,7 @@
 ; CHECK:       bb2:
 ; CHECK-NEXT:    br label [[BB3]]
 ; CHECK:       bb3:
-; CHECK-NEXT:    [[TMP0:%.*]] = phi <2 x i32> [ undef, [[BB1]] ], [ poison, [[BB2:%.*]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = phi <2 x i32> [ undef, [[BB1]] ], [ undef, [[BB2:%.*]] ]
 ; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x i32> [[TMP0]], <2 x i32> poison, <8 x i32> <i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 1>
 ; CHECK-NEXT:    [[TMP1:%.*]] = extractelement <8 x i32> [[SHUFFLE]], i32 0
 ; CHECK-NEXT:    [[TMP2:%.*]] = insertelement <16 x i32> poison, i32 [[TMP1]], i32 0
Index: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -4750,7 +4750,8 @@
       // Keeps the reordered operands to avoid code duplication.
       SmallVector<ValueList, 2> OperandsVec;
       for (unsigned I = 0, E = PH->getNumIncomingValues(); I < E; ++I) {
-        if (!DT->isReachableFromEntry(PH->getIncomingBlock(I))) {
+        if (!DT->isReachableFromEntry(PH->getIncomingBlock(I)) &&
+            !isa<UndefValue>(PH->getIncomingValue(I))) {
           ValueList Operands(VL.size(), PoisonValue::get(PH->getType()));
           TE->setOperand(I, Operands);
           OperandsVec.push_back(Operands);


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D126895.433848.patch
Type: text/x-patch
Size: 2442 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20220602/87d1a8d2/attachment.bin>