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| author | Bill Wendling <isanbard@gmail.com> | 2009-10-27 22:48:31 +0000 |
|---|---|---|
| committer | Bill Wendling <isanbard@gmail.com> | 2009-10-27 22:48:31 +0000 |
| commit | 5a5692734541abe3c218b5c5eedbd84b0c0162a9 (patch) | |
| tree | 27fb2c9b6aca12d3d2def0aa0e1aa3034055be4d /lib/Target/X86/README.txt | |
| parent | 3dab2778571b5bb00b35a0adcb7011dc85158beb (diff) | |
| download | external_llvm-5a5692734541abe3c218b5c5eedbd84b0c0162a9.zip external_llvm-5a5692734541abe3c218b5c5eedbd84b0c0162a9.tar.gz external_llvm-5a5692734541abe3c218b5c5eedbd84b0c0162a9.tar.bz2 | |
Move and clarify note.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85334 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Target/X86/README.txt')
| -rw-r--r-- | lib/Target/X86/README.txt | 31 |
1 files changed, 0 insertions, 31 deletions
diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt index 876bb65..9b7aab8 100644 --- a/lib/Target/X86/README.txt +++ b/lib/Target/X86/README.txt @@ -1954,34 +1954,3 @@ carried over to machine instructions. Asm printer (or JIT) can use this information to add the "lock" prefix. //===---------------------------------------------------------------------===// - -int func(int a, int b) { if (a & 0x80) b |= 0x80; else b &= ~0x80; return b; } - -Current: - - - movb %sil, %al - andb $127, %sil - orb $-128, %al - testb %dil, %dil - js LBB1_2 - movb %sil, %al -LBB1_2: - movsbl %al, %eax - - -Better: - - movl %esi, %eax - orl $-128, %eax - andl $127, %esi - testb %dil, %dil - cmovns %esi, %eax - movsbl %al,%eax - -Best (recognize this as 'b = (b & ~0x80) | (a & 0x80)'): - - andb $-128, %dil - andb $127, %sil - orb %dil, %sil - movsbl %sil, %eax |