This includes a fix so that it doesn't transform declarations, and it
puts the functionality under control of a command-line option which is off
by default to avoid breaking existing setups.
llvm-svn: 320196
This reverts commit 959e37e669b0c3cfad4cb9f1f7c9261ce9f5e9ae.
That commit doesn't handle the case where main is declared rather than defined,
in particular the even-more special case where main is a prototypeless
declaration (which is of course the one actually used by musl currently).
llvm-svn: 320121
WebAssembly requires caller and callee signatures to match, so the usual
C runtime trick of calling main and having it just work regardless of
whether main is defined as '()' or '(int argc, char *argv[])' doesn't
work. Extend the FixFunctionBitcasts pass to rewrite main to use the
latter form.
llvm-svn: 320041
Generalize FixFunctionBitcasts to handle varargs functions. This in
particular fixes the case where clang bitcasts away a varargs when
calling a K&R-style function.
This avoids interacting with tricky ABI details because it operates
at the LLVM IR level before varargs ABI details are exposed.
This fixes PR35385.
llvm-svn: 319186
Summary:
The pass to fix function bitcasts generates thunks for functions that
are called directly with a mismatching signature. It was also generating
thunks in cases where the function was address-taken, causing aliasing
problems in otherwise valid cases.
This patch tightens the restrictions for when the pass runs.
Reviewers: sunfish, dschuff
Subscribers: jfb, sbc100, llvm-commits, aheejin
Differential Revision: https://reviews.llvm.org/D38640
llvm-svn: 315326
WebAssembly varargs functions use a significantly different ABI than
non-varargs functions, and the current code in
WebAssemblyFixFunctionBitcasts doesn't handle that difference. For now,
just avoid creating wrapper functions in the presence of varargs.
llvm-svn: 292645
When we collect 2 uses of a function in FindUses and then RAUW when we
visit the first, we end up visiting the wrapper (because the second was
RAUW'd). We still want to use RAUW instead of just Use->set() because
it has special handling for Constants, so this patch just ensures that
only one use of each constant is added to the work list.
Differential Revision: https://reviews.llvm.org/D28504
llvm-svn: 291603
Gracefully leave code that performs function-pointer bitcasts implying
non-trivial pointer conversions alone, rather than aborting, since it's
just undefined behavior.
llvm-svn: 291326
WebAssembly requires caller and callee signatures to match exactly. In LLVM,
there are a variety of circumstances where signatures may be mismatched in
practice, and one can bitcast a function address to another type to call it
as that type. This patch adds a pass which replaces bitcasted function
addresses with wrappers to replace the bitcasts.
This doesn't catch everything, but it does match many common cases.
llvm-svn: 291315
Dan Gohman