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comparison gen/functions.cpp @ 1494:b243e28f63d4

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Generate less dead code by deleting unreachable blocks at the end of functions (which would otherwise appear if a function ends with a return, for example).
author Frits van Bommel <fvbommel wxs.nl>
date Fri, 12 Jun 2009 16:41:38 +0200
parents 93644700a0b3
children 2292878925f4
comparison
equal deleted inserted replaced
1493:7cca8cf730de 1494:b243e28f63d4
780 780
781 // TODO: clean up this mess 781 // TODO: clean up this mess
782 782
783 // std::cout << *func << std::endl; 783 // std::cout << *func << std::endl;
784 784
785 // llvm requires all basic blocks to end with a TerminatorInst but DMD does not put a return statement 785 llvm::BasicBlock* bb = gIR->scopebb();
786 // in automatically, so we do it here. 786 if (pred_begin(bb) == pred_end(bb) && bb != &bb->getParent()->getEntryBlock()) {
787 if (!gIR->scopereturned()) { 787 // This block is trivially unreachable, so just delete it.
788 // (This is a common case because it happens when 'return'
789 // is the last statement in a function)
790 bb->eraseFromParent();
791 } else if (!gIR->scopereturned()) {
792 // llvm requires all basic blocks to end with a TerminatorInst but DMD does not put a return statement
793 // in automatically, so we do it here.
794
788 // pass the previous block into this block 795 // pass the previous block into this block
789 if (global.params.symdebug) DtoDwarfFuncEnd(fd); 796 if (global.params.symdebug) DtoDwarfFuncEnd(fd);
790 if (func->getReturnType() == LLType::VoidTy) { 797 if (func->getReturnType() == LLType::VoidTy) {
791 llvm::ReturnInst::Create(gIR->scopebb()); 798 llvm::ReturnInst::Create(gIR->scopebb());
792 } 799 }
793 else { 800 else if (!fd->isMain()) {
794 if (!fd->isMain()) 801 AsmBlockStatement* asmb = fd->fbody->endsWithAsm();
795 { 802 if (asmb) {
796 AsmBlockStatement* asmb = fd->fbody->endsWithAsm(); 803 assert(asmb->abiret);
797 if (asmb) { 804 llvm::ReturnInst::Create(asmb->abiret, bb);
798 assert(asmb->abiret);
799 llvm::ReturnInst::Create(asmb->abiret, gIR->scopebb());
800 }
801 else {
802 llvm::ReturnInst::Create(llvm::UndefValue::get(func->getReturnType()), gIR->scopebb());
803 }
804 } 805 }
805 else 806 else {
806 llvm::ReturnInst::Create(llvm::Constant::getNullValue(func->getReturnType()), gIR->scopebb()); 807 llvm::ReturnInst::Create(llvm::UndefValue::get(func->getReturnType()), bb);
807 } 808 }
809 }
810 else
811 llvm::ReturnInst::Create(llvm::Constant::getNullValue(func->getReturnType()), bb);
808 } 812 }
809 813
810 // std::cout << *func << std::endl; 814 // std::cout << *func << std::endl;
811 815
812 // erase alloca point 816 // erase alloca point