Retry: [ubsan] Detect UB loads from bitfields
It's possible to load out-of-range values from bitfields backed by a
boolean or an enum. Check for UB loads from bitfields.
This is the motivating example:
struct S {
BOOL b : 1; // Signed ObjC BOOL.
};
S s;
s.b = 1; // This is actually stored as -1.
if (s.b == 1) // Evaluates to false, -1 != 1.
...
Changes since the original commit:
- Single-bit bools are a special case (see CGF::EmitFromMemory), and we
can't avoid dealing with them when loading from a bitfield. Don't try to
insert a check in this case.
Differential Revision: https://reviews.llvm.org/D30423
llvm-svn: 297389
diff --git a/clang/lib/CodeGen/CGAtomic.cpp b/clang/lib/CodeGen/CGAtomic.cpp
index 9287e46..28e20b5 100644
--- a/clang/lib/CodeGen/CGAtomic.cpp
+++ b/clang/lib/CodeGen/CGAtomic.cpp
@@ -1181,7 +1181,7 @@
if (LVal.isBitField())
return CGF.EmitLoadOfBitfieldLValue(
LValue::MakeBitfield(addr, LVal.getBitFieldInfo(), LVal.getType(),
- LVal.getAlignmentSource()));
+ LVal.getAlignmentSource()), loc);
if (LVal.isVectorElt())
return CGF.EmitLoadOfLValue(
LValue::MakeVectorElt(addr, LVal.getVectorIdx(), LVal.getType(),