[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

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
index b61bc0a..f5ef35a 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
@@ -163,6 +163,10 @@ void WebAssemblyPassConfig::addIRPasses() {
     // control specifically what gets lowered.
     addPass(createAtomicExpandPass(TM));
 
+  // Fix function bitcasts, as WebAssembly requires caller and callee signatures
+  // to match.
+  addPass(createWebAssemblyFixFunctionBitcasts());
+
   // Optimize "returned" function attributes.
   if (getOptLevel() != CodeGenOpt::None)
     addPass(createWebAssemblyOptimizeReturned());