[PATCH] D126371: [SLP]Fix PR55688: Miscompile due to incorrect nuw handling.

[Alexey Bataev via Phabricator via llvm-commits]

ABataev created this revision.
ABataev added reviewers: RKSimon, mkazantsev.
Herald added subscribers: vporpo, hiraditya.
Herald added a project: All.
ABataev requested review of this revision.
Herald added a project: LLVM.

Need gto use all ReductionOps when propagating flags for the reduction
ops, otherwise transformation is not correct.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D126371

Files:
  llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
  llvm/test/Transforms/SLPVectorizer/X86/horizontal-list.ll


Index: llvm/test/Transforms/SLPVectorizer/X86/horizontal-list.ll
===================================================================
--- llvm/test/Transforms/SLPVectorizer/X86/horizontal-list.ll
+++ llvm/test/Transforms/SLPVectorizer/X86/horizontal-list.ll
@@ -1001,8 +1001,8 @@
 ; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq <4 x i32> [[TMP2]], zeroinitializer
 ; CHECK-NEXT:    [[TMP5:%.*]] = sext <4 x i1> [[TMP4]] to <4 x i32>
 ; CHECK-NEXT:    [[TMP6:%.*]] = call i32 @llvm.vector.reduce.add.v4i32(<4 x i32> [[TMP5]])
-; CHECK-NEXT:    [[OP_RDX:%.*]] = add nuw i32 [[TMP3]], [[ARG]]
-; CHECK-NEXT:    [[OP_RDX2:%.*]] = add nsw i32 [[TMP6]], [[OP_RDX]]
+; CHECK-NEXT:    [[OP_RDX:%.*]] = add i32 [[TMP3]], [[ARG]]
+; CHECK-NEXT:    [[OP_RDX2:%.*]] = add i32 [[TMP6]], [[OP_RDX]]
 ; CHECK-NEXT:    ret i32 [[OP_RDX2]]
 ;
 ; THRESHOLD-LABEL: @wobble(
@@ -1016,8 +1016,8 @@
 ; THRESHOLD-NEXT:    [[TMP4:%.*]] = icmp eq <4 x i32> [[TMP2]], zeroinitializer
 ; THRESHOLD-NEXT:    [[TMP5:%.*]] = sext <4 x i1> [[TMP4]] to <4 x i32>
 ; THRESHOLD-NEXT:    [[TMP6:%.*]] = call i32 @llvm.vector.reduce.add.v4i32(<4 x i32> [[TMP5]])
-; THRESHOLD-NEXT:    [[OP_RDX:%.*]] = add nuw i32 [[TMP3]], [[ARG]]
-; THRESHOLD-NEXT:    [[OP_RDX2:%.*]] = add nsw i32 [[TMP6]], [[OP_RDX]]
+; THRESHOLD-NEXT:    [[OP_RDX:%.*]] = add i32 [[TMP3]], [[ARG]]
+; THRESHOLD-NEXT:    [[OP_RDX2:%.*]] = add i32 [[TMP6]], [[OP_RDX]]
 ; THRESHOLD-NEXT:    ret i32 [[OP_RDX2]]
 ;
   bb:
Index: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -11031,10 +11031,6 @@
             for (unsigned I = 0, E = (Sz / 2) * 2; I < E; I += 2) {
               Instruction *RedOp = InstVals[I + 1].first;
               Builder.SetCurrentDebugLocation(RedOp->getDebugLoc());
-              ReductionOpsListType Ops;
-              if (auto *Sel = dyn_cast<SelectInst>(RedOp))
-                Ops.emplace_back().push_back(Sel->getCondition());
-              Ops.emplace_back().push_back(RedOp);
               Value *RdxVal1 = InstVals[I].second;
               Value *StableRdxVal1 = RdxVal1;
               auto It1 = TrackedVals.find(RdxVal1);
@@ -11046,7 +11042,7 @@
               if (It2 != TrackedVals.end())
                 StableRdxVal2 = It2->second;
               Value *ExtraRed = createOp(Builder, RdxKind, StableRdxVal1,
-                                         StableRdxVal2, "op.rdx", Ops);
+                                         StableRdxVal2, "op.rdx", ReductionOps);
               ExtraReds[I / 2] = std::make_pair(InstVals[I].first, ExtraRed);
             }
             if (Sz % 2 == 1)
@@ -11081,17 +11077,13 @@
       if (ExtraReductions.size() == 1) {
         Instruction *RedOp = ExtraReductions.back().first;
         Builder.SetCurrentDebugLocation(RedOp->getDebugLoc());
-        ReductionOpsListType Ops;
-        if (auto *Sel = dyn_cast<SelectInst>(RedOp))
-          Ops.emplace_back().push_back(Sel->getCondition());
-        Ops.emplace_back().push_back(RedOp);
         Value *RdxVal = ExtraReductions.back().second;
         Value *StableRdxVal = RdxVal;
         auto It = TrackedVals.find(RdxVal);
         if (It != TrackedVals.end())
           StableRdxVal = It->second;
         VectorizedTree = createOp(Builder, RdxKind, VectorizedTree,
-                                  StableRdxVal, "op.rdx", Ops);
+                                  StableRdxVal, "op.rdx", ReductionOps);
       }
 
       ReductionRoot->replaceAllUsesWith(VectorizedTree);


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