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| author | Alan Cox <alc@FreeBSD.org> | 2005-04-10 18:12:07 +0000 |
|---|---|---|
| committer | Alan Cox <alc@FreeBSD.org> | 2005-04-10 18:12:07 +0000 |
| commit | fb41e047872b0a25b526e2873d9d15b7a338036c (patch) | |
| tree | 42943daf777a27a748439ed3aa93f02cca498624 /sys/amd64 | |
| parent | 313bcc9cb8f70f4dab2d63dc072d932ff8e42aa9 (diff) | |
| download | src-fb41e047872b0a25b526e2873d9d15b7a338036c.tar.gz src-fb41e047872b0a25b526e2873d9d15b7a338036c.zip | |
Eliminate a conditional branch and as a side-effect eliminate a branch to
a return instruction. (The latter is discouraged by the Opteron
optimization manual because it disables branch prediction for the return
instruction.)
Reviewed by: bde
Notes
Notes:
svn path=/head/; revision=144868
Diffstat (limited to 'sys/amd64')
| -rw-r--r-- | sys/amd64/amd64/support.S | 7 |
1 files changed, 2 insertions, 5 deletions
diff --git a/sys/amd64/amd64/support.S b/sys/amd64/amd64/support.S index ba6f3c22f0b5..3d4098e318d2 100644 --- a/sys/amd64/amd64/support.S +++ b/sys/amd64/amd64/support.S @@ -86,8 +86,6 @@ ENTRY(pagezero) ret ENTRY(bcmp) - xorq %rax,%rax - movq %rdx,%rcx shrq $3,%rcx cld /* compare forwards */ @@ -99,10 +97,9 @@ ENTRY(bcmp) andq $7,%rcx repe cmpsb - je 2f 1: - incq %rax -2: + setne %al + movsbl %al,%eax ret /* |