[clang][UBSan] Sanitization for alignment assumptions.
Summary:
UB isn't nice. It's cool and powerful, but not nice.
Having a way to detect it is nice though.
[[ https://wg21.link/p1007r3 | P1007R3: std::assume_aligned ]] / http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1007r2.pdf says:
```
We propose to add this functionality via a library function instead of a core language attribute.
...
If the pointer passed in is not aligned to at least N bytes, calling assume_aligned results in undefined behaviour.
```
This differential teaches clang to sanitize all the various variants of this assume-aligned attribute.
Requires D54588 for LLVM IRBuilder changes.
The compiler-rt part is D54590.
This is a second commit, the original one was r351105,
which was mass-reverted in r351159 because 2 compiler-rt tests were failing.
Reviewers: ABataev, craig.topper, vsk, rsmith, rnk, #sanitizers, erichkeane, filcab, rjmccall
Reviewed By: rjmccall
Subscribers: chandlerc, ldionne, EricWF, mclow.lists, cfe-commits, bkramer
Tags: #sanitizers
Differential Revision: https://reviews.llvm.org/D54589
llvm-svn: 351177
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 12234eb..32c27ed 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -1904,15 +1904,17 @@
return RValue::get(Result);
}
case Builtin::BI__builtin_assume_aligned: {
- Value *PtrValue = EmitScalarExpr(E->getArg(0));
+ const Expr *Ptr = E->getArg(0);
+ Value *PtrValue = EmitScalarExpr(Ptr);
Value *OffsetValue =
(E->getNumArgs() > 2) ? EmitScalarExpr(E->getArg(2)) : nullptr;
Value *AlignmentValue = EmitScalarExpr(E->getArg(1));
ConstantInt *AlignmentCI = cast<ConstantInt>(AlignmentValue);
- unsigned Alignment = (unsigned) AlignmentCI->getZExtValue();
+ unsigned Alignment = (unsigned)AlignmentCI->getZExtValue();
- EmitAlignmentAssumption(PtrValue, Alignment, OffsetValue);
+ EmitAlignmentAssumption(PtrValue, Ptr, /*The expr loc is sufficient.*/ SourceLocation(),
+ Alignment, OffsetValue);
return RValue::get(PtrValue);
}
case Builtin::BI__assume: