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apparently tailcalls are better on darwin/x86-64 than on linux?

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119947 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2010-11-21 18:59:20 +00:00
parent dd061b2854
commit 8bc1e45295
1 changed files with 18 additions and 0 deletions
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18
lib/Target/X86/README.txt
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@ -895,6 +895,24 @@ compare:
//===---------------------------------------------------------------------===// //===---------------------------------------------------------------------===//
Linux is missing some basic tail call support:
#include <math.h>
double foo(double a) { return sin(a); }
This compiles into this on x86-64 Linux (but not darwin):
foo:
subq $8, %rsp
call sin
addq $8, %rsp
ret
vs:
foo:
jmp sin
//===---------------------------------------------------------------------===//
Tail call optimization improvements: Tail call optimization currently Tail call optimization improvements: Tail call optimization currently
pushes all arguments on the top of the stack (their normal place for pushes all arguments on the top of the stack (their normal place for
non-tail call optimized calls) that source from the callers arguments non-tail call optimized calls) that source from the callers arguments