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MCExpr: Avoid UB by evaluating this shift as unsigned

We hit undefined behaviour in some MCExpr tests when the LHS of a left
shift is -1. Twos-complement semantics are completely reasonable here,
so we should just do the shift in unsigned.

llvm-svn: 240385
This commit is contained in:
Justin Bogner 2015-06-23 07:32:55 +00:00
parent 996cc0afa2
commit 394227380b

View File

@ -752,7 +752,7 @@ bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
case MCBinaryExpr::Mul: Result = LHS * RHS; break;
case MCBinaryExpr::NE: Result = LHS != RHS; break;
case MCBinaryExpr::Or: Result = LHS | RHS; break;
case MCBinaryExpr::Shl: Result = LHS << RHS; break;
case MCBinaryExpr::Shl: Result = uint64_t(LHS) << uint64_t(RHS); break;
case MCBinaryExpr::Sub: Result = LHS - RHS; break;
case MCBinaryExpr::Xor: Result = LHS ^ RHS; break;
}