[Scalarizer] visit{Insert,Extract}ElementInst(): avoid call arg evalu…

…ation order deps Compilers may evaluate call arguments in different order, which would result in different order of IR, which would break the tests. Spotted thanks to Dmitri Gribenko!
llvm · Jul 6, 2020 · 5d7afe2 · 5d7afe2
1 parent 60b8b2b
commit 5d7afe2
Showing 1 changed file with 10 additions and 6 deletions.
diff --git a/llvm/lib/Transforms/Scalar/Scalarizer.cpp b/llvm/lib/Transforms/Scalar/Scalarizer.cpp
@@ -769,10 +769,12 @@ bool ScalarizerVisitor::visitInsertElementInst(InsertElementInst &IEI) {
       return false;
 
     for (unsigned I = 0; I < NumElems; ++I) {
-      Res[I] = Builder.CreateSelect(
+      Value *ShouldReplace =
           Builder.CreateICmpEQ(InsIdx, ConstantInt::get(InsIdx->getType(), I),
-                               InsIdx->getName() + ".is." + Twine(I)),
-          NewElt, Op0[I], IEI.getName() + ".i" + Twine(I));
+                               InsIdx->getName() + ".is." + Twine(I));
+      Value *OldElt = Op0[I];
+      Res[I] = Builder.CreateSelect(ShouldReplace, NewElt, OldElt,
+                                    IEI.getName() + ".i" + Twine(I));
     }
   }
 
@@ -801,10 +803,12 @@ bool ScalarizerVisitor::visitExtractElementInst(ExtractElementInst &EEI) {
 
   Value *Res = UndefValue::get(VT->getElementType());
   for (unsigned I = 0; I < NumSrcElems; ++I) {
-    Res = Builder.CreateSelect(
+    Value *ShouldExtract =
         Builder.CreateICmpEQ(ExtIdx, ConstantInt::get(ExtIdx->getType(), I),
-                             ExtIdx->getName() + ".is." + Twine(I)),
-        Op0[I], Res, EEI.getName() + ".upto" + Twine(I));
+                             ExtIdx->getName() + ".is." + Twine(I));
+    Value *Elt = Op0[I];
+    Res = Builder.CreateSelect(ShouldExtract, Elt, Res,
+                               EEI.getName() + ".upto" + Twine(I));
   }
   gather(&EEI, {Res});
   return true;