vendor/llvm/llvm-trunk-r240225

1 files changed, 12 insertions, 1 deletions

diff --git a/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp b/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp
index 453503ab61da..f32769c24110 100644
--- a/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp
@@ -265,8 +265,10 @@ static bool isGEPFoldable(GetElementPtrInst *GEP,
       BaseOffset += DL->getStructLayout(STy)->getElementOffset(Field);
     }
   }
+
+  unsigned AddrSpace = GEP->getPointerAddressSpace();
   return TTI->isLegalAddressingMode(GEP->getType()->getElementType(), BaseGV,
-                                    BaseOffset, HasBaseReg, Scale);
+                                    BaseOffset, HasBaseReg, Scale, AddrSpace);
 }
 
 // Returns whether (Base + Index * Stride) can be folded to an addressing mode.
@@ -630,6 +632,15 @@ void StraightLineStrengthReduce::rewriteCandidateWithBasis(
       // trivially dead.
       RecursivelyDeleteTriviallyDeadInstructions(Bump);
     } else {
+      // It's tempting to preserve nsw on Bump and/or Reduced. However, it's
+      // usually unsound, e.g.,
+      //
+      // X = (-2 +nsw 1) *nsw INT_MAX
+      // Y = (-2 +nsw 3) *nsw INT_MAX
+      //   =>
+      // Y = X + 2 * INT_MAX
+      //
+      // Neither + and * in the resultant expression are nsw.
       Reduced = Builder.CreateAdd(Basis.Ins, Bump);
     }
     break;