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Avoid unused allocas for immediate return values

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There's no need to allocate a return slot for anykind of immediate
return value, not just not for nils. Also, when the return value is
ignored, we only have to copy it to a temporary alloca if it's actually
required to call drop_ty on it.
This commit is contained in:
Björn Steinbrink 2013-07-08 07:42:56 +02:00 committed by Björn Steinbrink
parent 48ad726f2a
commit 4a485f8cec
1 changed files with 3 additions and 10 deletions
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13
src/librustc/middle/trans/callee.rs
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@ -672,15 +672,8 @@ pub fn trans_call_inner(in_cx: block,
expr::Ignore => {
// drop the value if it is not being saved.
unsafe {
if llvm::LLVMIsUndef(llretslot) != lib::llvm::True {
if ty::type_is_nil(ret_ty) {
// When implementing the for-loop sugar syntax, the
// type of the for-loop is nil, but the function
// it's invoking returns a bool. This is a special
// case to ignore instead of invoking the Store
// below into a scratch pointer of a mismatched
// type.
} else if ty::type_is_immediate(bcx.tcx(), ret_ty) {
if ty::type_needs_drop(bcx.tcx(), ret_ty) {
if ty::type_is_immediate(bcx.tcx(), ret_ty) {
let llscratchptr = alloc_ty(bcx, ret_ty);
Store(bcx, llresult, llscratchptr);
bcx = glue::drop_ty(bcx, llscratchptr, ret_ty);
@ -734,7 +727,7 @@ pub fn trans_ret_slot(bcx: block, fn_ty: ty::t, dest: expr::Dest)
match dest {
expr::SaveIn(dst) => dst,
expr::Ignore => {
if ty::type_is_nil(retty) {
if ty::type_is_immediate(bcx.tcx(), retty) {
unsafe {
llvm::LLVMGetUndef(Type::nil().ptr_to().to_ref())
}