Temporarily reverting r71008. It was causing this failure:

Running /Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvm.src/test/
CodeGen/X86/dg.exp ...
FAIL: /Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvm.src/test/
CodeGen/X86/change-compare-stride-1.ll
Failed with exit(1) at line 2
while running: grep {cmpq       $-478,} change-compare-stride-1.ll.tmp
child process exited abnormally



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71013 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 23f7563..4365adc 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -2027,10 +2027,9 @@
 
       Scale = SSInt / CmpSSInt;
       int64_t NewCmpVal = CmpVal * Scale;
-      APInt Mul = APInt(BitWidth*2, CmpVal);
-      Mul = Mul * APInt(BitWidth*2, Scale);
+      APInt Mul = APInt(BitWidth, NewCmpVal);
       // Check for overflow.
-      if (!Mul.isSignedIntN(BitWidth))
+      if (Mul.getSExtValue() != NewCmpVal)
         continue;
 
       // Watch out for overflow.