[SLP]Fix insertpoint of the extractellements instructions to avoid reshuffle crash.

Need to set the insertpoint for extractelement to point to the first
instruction in the node to avoid possible crash during external uses
combine  process. Without it we may endup with the incorrect
transformation.

Differential Revision: https://reviews.llvm.org/D135591

diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 10d9293..865578f 100644 (file)
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -7693,13 +7693,34 @@ Instruction &BoUpSLP::getLastInstructionInBundle(const TreeEntry *E) {
     return LastInst;
   };
 
-  auto &&FindFirstInst = [E, Front]() {
+  auto &&FindFirstInst = [E, Front, this]() {
     Instruction *FirstInst = Front;
     for (Value *V : E->Scalars) {
       auto *I = dyn_cast<Instruction>(V);
       if (!I)
         continue;
-      if (I->comesBefore(FirstInst))
+      if (FirstInst->getParent() == I->getParent()) {
+        if (I->comesBefore(FirstInst))
+          FirstInst = I;
+        continue;
+      }
+      assert(isVectorLikeInstWithConstOps(FirstInst) &&
+             isVectorLikeInstWithConstOps(I) &&
+             "Expected vector-like insts only.");
+      if (!DT->isReachableFromEntry(FirstInst->getParent())) {
+        FirstInst = I;
+        continue;
+      }
+      if (!DT->isReachableFromEntry(I->getParent()))
+        continue;
+      auto *NodeA = DT->getNode(FirstInst->getParent());
+      auto *NodeB = DT->getNode(I->getParent());
+      assert(NodeA && "Should only process reachable instructions");
+      assert(NodeB && "Should only process reachable instructions");
+      assert((NodeA == NodeB) ==
+                 (NodeA->getDFSNumIn() == NodeB->getDFSNumIn()) &&
+             "Different nodes should have different DFS numbers");
+      if (NodeA->getDFSNumIn() > NodeB->getDFSNumIn())
         FirstInst = I;
     }
     return FirstInst;
@@ -7708,9 +7729,12 @@ Instruction &BoUpSLP::getLastInstructionInBundle(const TreeEntry *E) {
   // Set the insert point to the beginning of the basic block if the entry
   // should not be scheduled.
   if (E->State != TreeEntry::NeedToGather &&
-      doesNotNeedToSchedule(E->Scalars)) {
+      (doesNotNeedToSchedule(E->Scalars) ||
+       all_of(E->Scalars, isVectorLikeInstWithConstOps))) {
     Instruction *InsertInst;
-    if (all_of(E->Scalars, isUsedOutsideBlock))
+    if (all_of(E->Scalars, [](Value *V) {
+          return !isVectorLikeInstWithConstOps(V) && isUsedOutsideBlock(V);
+        }))
       InsertInst = FindLastInst();
     else
       InsertInst = FindFirstInst();
@@ -8135,7 +8159,7 @@ Value *BoUpSLP::vectorizeTree(TreeEntry *E) {
 
     case Instruction::ExtractElement: {
       Value *V = E->getSingleOperand(0);
-      Builder.SetInsertPoint(VL0);
+      setInsertPointAfterBundle(E);
       ShuffleBuilder.addInversedMask(E->ReorderIndices);
       ShuffleBuilder.addMask(E->ReuseShuffleIndices);
       V = ShuffleBuilder.finalize(V);

diff --git a/llvm/test/Transforms/SLPVectorizer/X86/extractelement-insertpoint.ll b/llvm/test/Transforms/SLPVectorizer/X86/extractelement-insertpoint.ll
new file mode 100644 (file)
index 0000000..0d53121
--- /dev/null
+++ b/llvm/test/Transforms/SLPVectorizer/X86/extractelement-insertpoint.ll
@@ -0,0 +1,31 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -slp-vectorizer -mtriple=x86_64-grtev4-linux-gnu -o - < %s | FileCheck %s
+
+define i32 @crash() {
+; CHECK-LABEL: @crash(
+; CHECK-NEXT:  label:
+; CHECK-NEXT:    [[ADD:%.*]] = fadd <2 x double> zeroinitializer, zeroinitializer
+; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x double> [[ADD]], <2 x double> poison, <2 x i32> <i32 1, i32 0>
+; CHECK-NEXT:    [[TMP0:%.*]] = shufflevector <2 x double> zeroinitializer, <2 x double> [[SHUFFLE]], <2 x i32> <i32 2, i32 1>
+; CHECK-NEXT:    [[TMP1:%.*]] = fmul <2 x double> [[SHUFFLE]], zeroinitializer
+; CHECK-NEXT:    [[TMP2:%.*]] = extractelement <2 x double> [[TMP1]], i32 0
+; CHECK-NEXT:    [[TMP3:%.*]] = extractelement <2 x double> [[TMP1]], i32 1
+; CHECK-NEXT:    [[ADD1:%.*]] = fadd double [[TMP2]], [[TMP3]]
+; CHECK-NEXT:    [[MUL1:%.*]] = fmul double [[ADD1]], 0.000000e+00
+; CHECK-NEXT:    store double [[MUL1]], double* null, align 16
+; CHECK-NEXT:    ret i32 0
+;
+label:
+  %0 = extractelement <2 x double> zeroinitializer, i64 1
+  %1 = extractelement <2 x double> zeroinitializer, i64 0
+  %add = fadd <2 x double> zeroinitializer, zeroinitializer
+  %extract1 = extractelement <2 x double> %add, i64 1
+  %2 = fmul double %extract1, %1
+  %insert = insertelement <2 x double> zeroinitializer, double %extract1, i64 0
+  %extract0 = extractelement <2 x double> %add, i64 0
+  %mul = fmul double %extract0, %0
+  %add1 = fadd double %2, %mul
+  %mul1 = fmul double %add1, 0.000000e+00
+  store double %mul1, double* null, align 16
+  ret i32 0
+}