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| author | Chris Lattner <sabre@nondot.org> | 2007-11-02 17:04:20 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2007-11-02 17:04:20 +0000 |
| commit | 253945899ba32793894b9983bce7cce3cb90b6d6 (patch) | |
| tree | 250499df5eeae464bbf9df2d35d218f6095171d5 | |
| parent | e414cdacb4ee442624128e41cb985c4e9f312b52 (diff) | |
add a note
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43642 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Target/X86/README.txt | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt index 567d5c4ebb..9a5ca427e1 100644 --- a/lib/Target/X86/README.txt +++ b/lib/Target/X86/README.txt @@ -651,6 +651,26 @@ _f: etc. +Another is: +int usesbb(unsigned int a, unsigned int b) { + return (a < b ? -1 : 0); +} +to: +_usesbb: + movl 8(%esp), %eax + cmpl %eax, 4(%esp) + sbbl %eax, %eax + ret + +instead of: +_usesbb: + xorl %eax, %eax + movl 8(%esp), %ecx + cmpl %ecx, 4(%esp) + movl $4294967295, %ecx + cmovb %ecx, %eax + ret + //===---------------------------------------------------------------------===// Currently we don't have elimination of redundant stack manipulations. Consider |