[PATCH] D154175: [SLP] Fix crash on attempt to access on invalid iterator state.

[Valeriy Dmitriev via Phabricator via llvm-commits]

vdmitrie created this revision.
vdmitrie added a reviewer: ABataev.
Herald added subscribers: vporpo, hiraditya.
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vdmitrie requested review of this revision.
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The patch fixes corner case when no of scalar instructions
required scheduling for vectorized node.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D154175

Files:
  llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
  llvm/test/Transforms/SLPVectorizer/X86/no-scheduled-instructions.ll


Index: llvm/test/Transforms/SLPVectorizer/X86/no-scheduled-instructions.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/SLPVectorizer/X86/no-scheduled-instructions.ll
@@ -0,0 +1,40 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
+; RUN: opt -S -passes=slp-vectorizer -mattr=+avx -mtriple=x86_64 < %s | FileCheck %s
+
+define void @test() {
+; CHECK-LABEL: define void @test
+; CHECK-SAME: () #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT:    br i1 undef, label [[BB1:%.*]], label [[BB2:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    [[TMP1:%.*]] = call i32 @llvm.vector.reduce.mul.v8i32(<8 x i32> <i32 0, i32 0, i32 0, i32 0, i32 undef, i32 undef, i32 undef, i32 undef>)
+; CHECK-NEXT:    call void @f(i32 noundef [[TMP1]])
+; CHECK-NEXT:    br label [[BB2]]
+; CHECK:       bb2:
+; CHECK-NEXT:    ret void
+;
+  %i27 = extractelement <4 x i32> poison, i64 0
+  %i28 = extractelement <4 x i32> poison, i64 1
+  %i29 = extractelement <4 x i32> poison, i64 2
+  %i30 = extractelement <4 x i32> poison, i64 3
+  %i31 = extractelement <4 x i32> zeroinitializer, i64 0
+  %i32 = extractelement <4 x i32> zeroinitializer, i64 1
+  %i33 = extractelement <4 x i32> zeroinitializer, i64 2
+  %i34 = extractelement <4 x i32> zeroinitializer, i64 3
+  br i1 undef, label %bb1, label %bb2
+
+bb1:
+  %i11 = mul nsw i32 %i28, %i27
+  %i12 = mul nsw i32 %i11, %i29
+  %i13 = mul nsw i32 %i12, %i30
+  %i14 = mul nsw i32 %i13, %i31
+  %i15 = mul nsw i32 %i14, %i32
+  %i16 = mul nsw i32 %i15, %i33
+  %i17 = mul nsw i32 %i16, %i34
+  call void @f(i32 noundef %i17)
+  br label %bb2
+
+bb2:
+  ret void
+}
+
+declare void @f(i32)
Index: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -9115,8 +9115,10 @@
   // bundle. The end of the bundle is marked by null ScheduleData.
   if (BlocksSchedules.count(BB)) {
     Value *V = E->isOneOf(E->Scalars.back());
-    if (doesNotNeedToBeScheduled(V))
-      V = *find_if_not(E->Scalars, doesNotNeedToBeScheduled);
+    if (auto *It = find_if_not(E->Scalars, doesNotNeedToBeScheduled);
+        It != E->Scalars.end())
+      V = *It;
+
     auto *Bundle = BlocksSchedules[BB]->getScheduleData(V);
     if (Bundle && Bundle->isPartOfBundle())
       for (; Bundle; Bundle = Bundle->NextInBundle)


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