Index: llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -2027,6 +2027,14 @@
     if (!PH) continue;
     if (PH->getNumIncomingValues() != 2) continue;
 
+    // If the calculation in integers overflows, the result in FP type will
+    // differ. So we only can do this transformation if we are guaranteed to not
+    // deal with overflowing values
+    const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(SE.getSCEV(PH));
+    if (!AR) continue;
+    if (IsSigned && !AR->hasNoSignedWrap()) continue;
+    if (!IsSigned && !AR->hasNoUnsignedWrap()) continue;
+
     Type *SrcTy = PH->getType();
     int Mantissa = DestTy->getFPMantissaWidth();
     if (Mantissa == -1) continue;
Index: llvm/trunk/test/Transforms/LoopStrengthReduce/X86/2008-08-14-ShadowIV.ll
===================================================================
--- llvm/trunk/test/Transforms/LoopStrengthReduce/X86/2008-08-14-ShadowIV.ll
+++ llvm/trunk/test/Transforms/LoopStrengthReduce/X86/2008-08-14-ShadowIV.ll
@@ -114,6 +114,100 @@
 	ret void
 }
 
+; Unable to eliminate cast because the integer IV overflows (accum exceeds
+; SINT_MAX).
+
+define i32 @foobar5() {
+; CHECK-LABEL:  foobar5(
+; CHECK-NOT:      phi double
+; CHECK-NOT:      phi float
+entry:
+  br label %loop
+
+loop:
+  %accum = phi i32 [ -3220, %entry ], [ %accum.next, %loop ]
+  %iv = phi i32 [ 12, %entry ], [ %iv.next, %loop ]
+  %tmp1 = sitofp i32 %accum to double
+  tail call void @foo( double %tmp1 ) nounwind
+  %accum.next = add i32 %accum, 9597741
+  %iv.next = add nuw nsw i32 %iv, 1
+  %exitcond = icmp ugt i32 %iv, 235
+  br i1 %exitcond, label %exit, label %loop
+
+exit:                                           ; preds = %loop
+  ret i32 %accum.next
+}
+
+; Can eliminate if we set nsw and, thus, think that we don't overflow SINT_MAX.
+
+define i32 @foobar6() {
+; CHECK-LABEL:  foobar6(
+; CHECK:          phi double
+
+entry:
+  br label %loop
+
+loop:
+  %accum = phi i32 [ -3220, %entry ], [ %accum.next, %loop ]
+  %iv = phi i32 [ 12, %entry ], [ %iv.next, %loop ]
+  %tmp1 = sitofp i32 %accum to double
+  tail call void @foo( double %tmp1 ) nounwind
+  %accum.next = add nsw i32 %accum, 9597741
+  %iv.next = add nuw nsw i32 %iv, 1
+  %exitcond = icmp ugt i32 %iv, 235
+  br i1 %exitcond, label %exit, label %loop
+
+exit:                                           ; preds = %loop
+  ret i32 %accum.next
+}
+
+; Unable to eliminate cast because the integer IV overflows (accum exceeds
+; UINT_MAX).
+
+define i32 @foobar7() {
+; CHECK-LABEL:  foobar7(
+; CHECK-NOT:      phi double
+; CHECK-NOT:      phi float
+entry:
+  br label %loop
+
+loop:
+  %accum = phi i32 [ -3220, %entry ], [ %accum.next, %loop ]
+  %iv = phi i32 [ 12, %entry ], [ %iv.next, %loop ]
+  %tmp1 = uitofp i32 %accum to double
+  tail call void @foo( double %tmp1 ) nounwind
+  %accum.next = add i32 %accum, 9597741
+  %iv.next = add nuw nsw i32 %iv, 1
+  %exitcond = icmp ugt i32 %iv, 235
+  br i1 %exitcond, label %exit, label %loop
+
+exit:                                           ; preds = %loop
+  ret i32 %accum.next
+}
+
+; Can eliminate if we set nuw and, thus, think that we don't overflow UINT_MAX.
+
+define i32 @foobar8() {
+; CHECK-LABEL:  foobar8(
+; CHECK:          phi double
+
+entry:
+  br label %loop
+
+loop:
+  %accum = phi i32 [ -3220, %entry ], [ %accum.next, %loop ]
+  %iv = phi i32 [ 12, %entry ], [ %iv.next, %loop ]
+  %tmp1 = uitofp i32 %accum to double
+  tail call void @foo( double %tmp1 ) nounwind
+  %accum.next = add nuw i32 %accum, 9597741
+  %iv.next = add nuw nsw i32 %iv, 1
+  %exitcond = icmp ugt i32 %iv, 235
+  br i1 %exitcond, label %exit, label %loop
+
+exit:                                           ; preds = %loop
+  ret i32 %accum.next
+}
+
 declare void @bar(i32)
 
 declare void @foo(double)