[SLSR] Fix crash on handling 128-bit integers.

    
ConstantInt::getSExtValue may fail on >64-bit integers. Add checks to call
getSExtValue only on narrow integers.

As a minor aside, simplify slsr-gep.ll to remove unnecessary load instructions.

llvm-svn: 274982

1 files changed, 20 insertions, 7 deletions

diff --git a/llvm/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp
index 411033bd583..77f0a78b928 100644
--- a/llvm/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp
@@ -246,7 +246,9 @@ static bool isGEPFoldable(GetElementPtrInst *GEP,
 // Returns whether (Base + Index * Stride) can be folded to an addressing mode.
 static bool isAddFoldable(const SCEV *Base, ConstantInt *Index, Value *Stride,
                           TargetTransformInfo *TTI) {
-  return TTI->isLegalAddressingMode(Base->getType(), nullptr, 0, true,
+  // Index->getSExtValue() may crash if Index is wider than 64-bit.
+  return Index->getBitWidth() <= 64 &&
+         TTI->isLegalAddressingMode(Base->getType(), nullptr, 0, true,
                                     Index->getSExtValue(), UnknownAddressSpace);
 }
 
@@ -502,13 +504,23 @@ void StraightLineStrengthReduce::allocateCandidatesAndFindBasisForGEP(
                                           IndexExprs, GEP->isInBounds());
     Value *ArrayIdx = GEP->getOperand(I);
     uint64_t ElementSize = DL->getTypeAllocSize(*GTI);
-    factorArrayIndex(ArrayIdx, BaseExpr, ElementSize, GEP);
+    if (ArrayIdx->getType()->getIntegerBitWidth() <=
+        DL->getPointerSizeInBits()) {
+      // Skip factoring if ArrayIdx is wider than the pointer size, because
+      // ArrayIdx is implicitly truncated to the pointer size.
+      factorArrayIndex(ArrayIdx, BaseExpr, ElementSize, GEP);
+    }
     // When ArrayIdx is the sext of a value, we try to factor that value as
     // well.  Handling this case is important because array indices are
     // typically sign-extended to the pointer size.
     Value *TruncatedArrayIdx = nullptr;
-    if (match(ArrayIdx, m_SExt(m_Value(TruncatedArrayIdx))))
+    if (match(ArrayIdx, m_SExt(m_Value(TruncatedArrayIdx))) &&
+        TruncatedArrayIdx->getType()->getIntegerBitWidth() <=
+            DL->getPointerSizeInBits()) {
+      // Skip factoring if TruncatedArrayIdx is wider than the pointer size,
+      // because TruncatedArrayIdx is implicitly truncated to the pointer size.
       factorArrayIndex(TruncatedArrayIdx, BaseExpr, ElementSize, GEP);
+    }
 
     IndexExprs[I - 1] = OrigIndexExpr;
   }
@@ -535,10 +547,11 @@ Value *StraightLineStrengthReduce::emitBump(const Candidate &Basis,
   if (Basis.CandidateKind == Candidate::GEP) {
     APInt ElementSize(
         IndexOffset.getBitWidth(),
-        DL->getTypeAllocSize(cast<GetElementPtrInst>(Basis.Ins)->getResultElementType()));
+        DL->getTypeAllocSize(
+            cast<GetElementPtrInst>(Basis.Ins)->getResultElementType()));
     APInt Q, R;
     APInt::sdivrem(IndexOffset, ElementSize, Q, R);
-    if (R.getSExtValue() == 0)
+    if (R == 0)
       IndexOffset = Q;
     else
       BumpWithUglyGEP = true;
@@ -546,10 +559,10 @@ Value *StraightLineStrengthReduce::emitBump(const Candidate &Basis,
 
   // Compute Bump = C - Basis = (i' - i) * S.
   // Common case 1: if (i' - i) is 1, Bump = S.
-  if (IndexOffset.getSExtValue() == 1)
+  if (IndexOffset == 1)
     return C.Stride;
   // Common case 2: if (i' - i) is -1, Bump = -S.
-  if (IndexOffset.getSExtValue() == -1)
+  if (IndexOffset.isAllOnesValue())
     return Builder.CreateNeg(C.Stride);
 
   // Otherwise, Bump = (i' - i) * sext/trunc(S). Note that (i' - i) and S may