bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

Disable all unwinding on -Z no-landing-pads LTO

Browse source 
When performing LTO, the rust compiler has an opportunity to completely strip
all landing pads in all dependent libraries. I've modified the LTO pass to
recognize the -Z no-landing-pads option when also running an LTO pass to flag
everything in LLVM as nothrow. I've verified that this prevents any and all
invoke instructions from being emitted.

I believe that this is one of our best options for moving forward with
accomodating use-cases where unwinding doesn't really make sense. This will
allow libraries to be built with landing pads by default but allow usage of them
in contexts where landing pads aren't necessary.

cc #10780
This commit is contained in:
Alex Crichton 2013-12-10 23:27:15 -08:00
parent b8b16ae099
commit 667d114f47
6 changed files with 34 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

21
src/rustllvm/PassWrapper.cpp
View file

@ -219,3 +219,24 @@ LLVMRustRunRestrictionPass(LLVMModuleRef M, char **symbols, size_t len) {
passes.add(llvm::createInternalizePass(ref));
passes.run(*unwrap(M));
}
extern "C" void
LLVMRustMarkAllFunctionsNounwind(LLVMModuleRef M) {
for (Module::iterator GV = unwrap(M)->begin(),
E = unwrap(M)->end(); GV != E; ++GV) {
GV->setDoesNotThrow();
Function *F = dyn_cast<Function>(GV);
if (F == NULL)
continue;
for (Function::iterator B = F->begin(), BE = F->end(); B != BE; ++B) {
for (BasicBlock::iterator I = B->begin(), IE = B->end();
I != IE; ++I) {
if (isa<InvokeInst>(I)) {
InvokeInst *CI = cast<InvokeInst>(I);
CI->setDoesNotThrow();
}
}
}
}
}