As reported in
https://github.com/llvm/llvm-project/pull/103714#issuecomment-2295769193.
CSA crashes on trying to bind value to symbolic region with `void *`.
This happens when such region gets passed as inline asm input and engine
tries to bind `UnknownVal` to that region.
Fix it by changing type from void to char before calling
`GetElementZeroRegion`
The new warning flag is `-Winvalid-gnu-asm-cast`, which is enabled by
default and is a downgradable diagnostic which defaults to an error.
This language dialect flag only controls whether a single diagnostic is
emitted as a warning or as an error, and has never been expanded to
include other behaviors. Given the rather perjorative name, it's better
for us to just expose a diagnostic flag for the one warning in question
and let the user elect to do `-Wno-error=` if they need to.
There's not a lot of use of the language dialect flag in the wild, but
there is some use of it. For the time being, this aliases the -f flag to
`-Wno-error=invalid-gnu-asm-cast`, but the -f flag can eventually be
removed.
If pointer is passed as input operand for inline assembly, it's possible
that asm block will change memory behind this pointer. So if pointer is
passed inside inline asm block, it's better to not guess and assume
memory has unknown state.
Without such change, we observed a lot of FP with hand-written `memcpy`
and friends.
Despite the fact that cast expressions return rvalues, GCC still
handles such outputs as lvalues when compiling inline assembler.
In this commit, we are treating it by removing LValueToRValue
casts inside GCCAsmStmt outputs.
Differential Revision: https://reviews.llvm.org/D45416
llvm-svn: 344864
