mirrors/ldc
1
0
Fork 0
mirror of https://github.com/ldc-developers/ldc.git synced 2025-04-30 23:20:40 +03:00
Code Issues Projects Releases Packages Wiki Activity Actions

Generate less dead code by deleting unreachable blocks at the end of functions

Browse source 
(which would otherwise appear if a function ends with a return, for example).
This commit is contained in:
Frits van Bommel 2009-06-12 16:41:38 +02:00
parent 8bcc2d9b3f
commit 25ebb3dbcd
1 changed files with 20 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

36
gen/functions.cpp
View file

@ -782,29 +782,33 @@ void DtoDefineFunction(FuncDeclaration* fd)
// std::cout << *func << std::endl; // std::cout << *func << std::endl;
// llvm requires all basic blocks to end with a TerminatorInst but DMD does not put a return statement llvm::BasicBlock* bb = gIR->scopebb();
// in automatically, so we do it here. if (pred_begin(bb) == pred_end(bb) && bb != &bb->getParent()->getEntryBlock()) {
if (!gIR->scopereturned()) { // This block is trivially unreachable, so just delete it.
// (This is a common case because it happens when 'return'
// is the last statement in a function)
bb->eraseFromParent();
} else if (!gIR->scopereturned()) {
// llvm requires all basic blocks to end with a TerminatorInst but DMD does not put a return statement
// in automatically, so we do it here.
// pass the previous block into this block // pass the previous block into this block
if (global.params.symdebug) DtoDwarfFuncEnd(fd); if (global.params.symdebug) DtoDwarfFuncEnd(fd);
if (func->getReturnType() == LLType::VoidTy) { if (func->getReturnType() == LLType::VoidTy) {
llvm::ReturnInst::Create(gIR->scopebb()); llvm::ReturnInst::Create(gIR->scopebb());
} }
else { else if (!fd->isMain()) {
if (!fd->isMain()) AsmBlockStatement* asmb = fd->fbody->endsWithAsm();
{ if (asmb) {
AsmBlockStatement* asmb = fd->fbody->endsWithAsm(); assert(asmb->abiret);
if (asmb) { llvm::ReturnInst::Create(asmb->abiret, bb);
assert(asmb->abiret); }
llvm::ReturnInst::Create(asmb->abiret, gIR->scopebb()); else {
} llvm::ReturnInst::Create(llvm::UndefValue::get(func->getReturnType()), bb);
else {
llvm::ReturnInst::Create(llvm::UndefValue::get(func->getReturnType()), gIR->scopebb());
}
} }
else
llvm::ReturnInst::Create(llvm::Constant::getNullValue(func->getReturnType()), gIR->scopebb());
} }
else
llvm::ReturnInst::Create(llvm::Constant::getNullValue(func->getReturnType()), bb);
} }
// std::cout << *func << std::endl; // std::cout << *func << std::endl;