[WebAssembly] Support bitcasted function addresses with varargs.

Generalize FixFunctionBitcasts to handle varargs functions. This in
particular fixes the case where clang bitcasts away a varargs whe

[WebAssembly] Support bitcasted function addresses with varargs.

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

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[WebAssembly] Narrow the scope of WebAssemblyFixFunctionBitcasts

Summary:
The pass to fix function bitcasts generates thunks for functions that
are called directly with a mismatching signature. It w

[WebAssembly] Narrow the scope of WebAssemblyFixFunctionBitcasts

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

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[WebAssembly] Add some comments and tidy up whitespace.

llvm-svn: 296402

[WebAssembly] Don't create bitcast-wrappers for varargs.

WebAssembly varargs functions use a significantly different ABI than
non-varargs functions, and the current code in
WebAssemblyFixFunctionBit

[WebAssembly] Don't create bitcast-wrappers for varargs.

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

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[WebAssembly] Only RAUW a constant once in FixFunctionBitcasts

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 sec

[WebAssembly] Only RAUW a constant once in FixFunctionBitcasts

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

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[WebAssembly] Don't abort on code with UB.

Gracefully leave code that performs function-pointer bitcasts implying
non-trivial pointer conversions alone, rather than aborting, since it's
just undefin

[WebAssembly] Don't abort on code with UB.

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

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[WebAssembly] Move a SmallVector to a more specific scope. NFC.

llvm-svn: 291324

[WebAssembly] Add a pass to create wrappers for function bitcasts.

WebAssembly requires caller and callee signatures to match exactly. In LLVM,
there are a variety of circumstances where signatures

[WebAssembly] Add a pass to create wrappers for function bitcasts.

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

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