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Pull EmitReturnBlock out of FinishFunction and catch unified return

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case correctly.

llvm-svn: 63068
This commit is contained in:
Daniel Dunbar
2009-01-26 23:27:52 +00:00
parent 03490f0ce1
commit fd346a3644
2 changed files with 45 additions and 7 deletions
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48
clang/lib/CodeGen/CodeGenFunction.cpp
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@@ -70,6 +70,45 @@ bool CodeGenFunction::hasAggregateLLVMType(QualType T) {
!T->isBlockPointerType();
}
void CodeGenFunction::EmitReturnBlock() {
// For cleanliness, we try to avoid emitting the return block for
// simple cases.
llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
if (CurBB) {
assert(!CurBB->getTerminator() && "Unexpected terminated block.");
// We have a valid insert point, reuse it if there are no explicit
// jumps to the return block.
if (ReturnBlock->use_empty())
delete ReturnBlock;
else
EmitBlock(ReturnBlock);
return;
}
// Otherwise, if the return block is the target of a single direct
// branch then we can just put the code in that block instead. This
// cleans up functions which started with a unified return block.
if (ReturnBlock->hasOneUse()) {
llvm::BranchInst *BI =
dyn_cast<llvm::BranchInst>(*ReturnBlock->use_begin());
if (BI && BI->isUnconditional() && BI->getSuccessor(0) == ReturnBlock) {
// Reset insertion point and delete the branch.
Builder.SetInsertPoint(BI->getParent());
BI->eraseFromParent();
delete ReturnBlock;
return;
}
}
// FIXME: We are at an unreachable point, there is no reason to emit
// the block unless it has uses. However, we still need a place to
// put the debug region.end for now.
EmitBlock(ReturnBlock);
}
void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
// Finish emission of indirect switches.
EmitIndirectSwitches();
@@ -77,13 +116,8 @@ void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
assert(BreakContinueStack.empty() &&
"mismatched push/pop in break/continue stack!");
// Emit function epilog (to return). For cleanliness, skip emission
// if we know it is safe (when it is unused and the current block is
// unterminated).
if (!ReturnBlock->use_empty() ||
!Builder.GetInsertBlock() ||
Builder.GetInsertBlock()->getTerminator())
EmitBlock(ReturnBlock);
// Emit function epilog (to return).
EmitReturnBlock();
// Emit debug descriptor for function end.
if (CGDebugInfo *DI = CGM.getDebugInfo()) {