Fix integer undefined behavior due to signed left shift overflow in LLVM.
Reviewed offline by chandlerc.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162623 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/CodeGenDAGPatterns.cpp b/utils/TableGen/CodeGenDAGPatterns.cpp
index 5225418..0842c00 100644
--- a/utils/TableGen/CodeGenDAGPatterns.cpp
+++ b/utils/TableGen/CodeGenDAGPatterns.cpp
@@ -1410,19 +1410,13 @@
// Make sure that the value is representable for this type.
if (Size >= 32) return MadeChange;
- int Val = (II->getValue() << (32-Size)) >> (32-Size);
- if (Val == II->getValue()) return MadeChange;
-
- // If sign-extended doesn't fit, does it fit as unsigned?
- unsigned ValueMask;
- unsigned UnsignedVal;
- ValueMask = unsigned(~uint32_t(0UL) >> (32-Size));
- UnsignedVal = unsigned(II->getValue());
-
- if ((ValueMask & UnsignedVal) == UnsignedVal)
+ // Check that the value doesn't use more bits than we have. It must either
+ // be a sign- or zero-extended equivalent of the original.
+ int64_t SignBitAndAbove = II->getValue() >> (Size - 1);
+ if (SignBitAndAbove == -1 || SignBitAndAbove == 0 || SignBitAndAbove == 1)
return MadeChange;
- TP.error("Integer value '" + itostr(II->getValue())+
+ TP.error("Integer value '" + itostr(II->getValue()) +
"' is out of range for type '" + getEnumName(getType(0)) + "'!");
return MadeChange;
}
@@ -3400,4 +3394,3 @@
DEBUG(errs() << "\n");
}
}
-