Disable inlining of recursive calls. It can complicate tailcallelim and

dependent analyses, and increase code size, so doing it profitably would
require more complex heuristics.

llvm-svn: 101471
This commit is contained in:
Dan Gohman 2010-04-16 16:01:18 +00:00
parent d9abbe56a5
commit f13f69f296
2 changed files with 36 additions and 0 deletions

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@ -263,6 +263,13 @@ InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS,
CS.isNoInline())
return llvm::InlineCost::getNever();
// Don't inline directly recursive calls, for now. Inlining a directly
// recursive call is effectively unrolling a loop, so it calls for different
// heuristics, which aren't implemented yet. Until then, err on the
// conservative side.
if (Callee == Caller)
return llvm::InlineCost::getNever();
// InlineCost - This value measures how good of an inline candidate this call
// site is to inline. A lower inline cost make is more likely for the call to
// be inlined. This value may go negative.

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@ -0,0 +1,29 @@
; RUN: opt -inline -tailcallelim -indvars -loop-deletion -S < %s | FileCheck %s
; Inline shouldn't inline foo into itself because it's a tailcallelim
; candidate. Tailcallelim should convert the call into a loop. Indvars
; should calculate the exit value, making the loop dead. Loop deletion
; should delete the loop.
; PR6842
; CHECK: define i32 @bar() nounwind {
; CHECK-NEXT: ret i32 10000
; CHECK-NEXT: }
define internal i32 @foo(i32 %x) nounwind {
%i = add i32 %x, 1 ; <i32> [#uses=3]
%a = icmp slt i32 %i, 10000 ; <i1> [#uses=1]
br i1 %a, label %more, label %done
done: ; preds = %0
ret i32 %i
more: ; preds = %0
%z = tail call i32 @foo(i32 %i) ; <i32> [#uses=1]
ret i32 %z
}
define i32 @bar() nounwind {
%z = call i32 @foo(i32 0) ; <i32> [#uses=1]
ret i32 %z
}