Fix PR18165: LSR must avoid scaling factors that exceed the limit on truncated use.

Patch by Michael Zolotukhin!

llvm-svn: 202273

1 files changed, 12 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index b25943011f3..093352ba572 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -3389,6 +3389,10 @@ void LSRInstance::GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx,
     int64_t NewBaseOffset = (uint64_t)Base.BaseOffset * Factor;
     if (NewBaseOffset / Factor != Base.BaseOffset)
       continue;
+    // If the offset will be truncated at this use, check that it is in bounds.
+    if (!IntTy->isPointerTy() &&
+        !ConstantInt::isValueValidForType(IntTy, NewBaseOffset))
+      continue;
 
     // Check that multiplying with the use offset doesn't overflow.
     int64_t Offset = LU.MinOffset;
@@ -3397,6 +3401,10 @@ void LSRInstance::GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx,
     Offset = (uint64_t)Offset * Factor;
     if (Offset / Factor != LU.MinOffset)
       continue;
+    // If the offset will be truncated at this use, check that it is in bounds.
+    if (!IntTy->isPointerTy() &&
+        !ConstantInt::isValueValidForType(IntTy, Offset))
+      continue;
 
     Formula F = Base;
     F.BaseOffset = NewBaseOffset;
@@ -3431,6 +3439,10 @@ void LSRInstance::GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx,
       F.UnfoldedOffset = (uint64_t)F.UnfoldedOffset * Factor;
       if (F.UnfoldedOffset / Factor != Base.UnfoldedOffset)
         continue;
+      // If the offset will be truncated, check that it is in bounds.
+      if (!IntTy->isPointerTy() &&
+          !ConstantInt::isValueValidForType(IntTy, F.UnfoldedOffset))
+        continue;
     }
 
     // If we make it here and it's legal, add it.