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| author | Sanjay Patel <spatel@rotateright.com> | 2016-05-20 14:09:41 +0000 |
|---|---|---|
| committer | Sanjay Patel <spatel@rotateright.com> | 2016-05-20 14:09:41 +0000 |
| commit | 42bbe77009b0875524f9f14b176c757393bf5da3 (patch) | |
| tree | aa07dc879197f1025e8154aa1efe0600c0059e7e /llvm/lib/MC/MCExpr.cpp | |
| parent | a053101c9516485afe9fb55daa0493ab8acc0eb8 (diff) | |
| download | llvm-42bbe77009b0875524f9f14b176c757393bf5da3.zip llvm-42bbe77009b0875524f9f14b176c757393bf5da3.tar.gz llvm-42bbe77009b0875524f9f14b176c757393bf5da3.tar.bz2 | |
[MCExpr] avoid UB via negation of INT_MIN
I accidentally exposed a bug in MCExpr::evaluateAsRelocatableImpl() with the test file added in:
http://reviews.llvm.org/rL269977
Differential Revision: http://reviews.llvm.org/D20434
llvm-svn: 270218
Diffstat (limited to 'llvm/lib/MC/MCExpr.cpp')
| -rw-r--r-- | llvm/lib/MC/MCExpr.cpp | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/llvm/lib/MC/MCExpr.cpp b/llvm/lib/MC/MCExpr.cpp index 4dfb971..6f90ff8 100644 --- a/llvm/lib/MC/MCExpr.cpp +++ b/llvm/lib/MC/MCExpr.cpp @@ -663,8 +663,10 @@ bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm, /// -(a - b + const) ==> (b - a - const) if (Value.getSymA() && !Value.getSymB()) return false; + + // The cast avoids undefined behavior if the constant is INT64_MIN. Res = MCValue::get(Value.getSymB(), Value.getSymA(), - -Value.getConstant()); + -(uint64_t)Value.getConstant()); break; case MCUnaryExpr::Not: if (!Value.isAbsolute()) @@ -697,9 +699,10 @@ bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm, return false; case MCBinaryExpr::Sub: // Negate RHS and add. + // The cast avoids undefined behavior if the constant is INT64_MIN. return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, RHSValue.getSymB(), RHSValue.getSymA(), - -RHSValue.getConstant(), Res); + -(uint64_t)RHSValue.getConstant(), Res); case MCBinaryExpr::Add: return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue, |