Author: lattner
Date: Sat Aug 11 13:19:07 2007
New Revision: 41021
URL: http://llvm.org/viewvc/llvm-project?rev=41021&view=rev
Log:
expand a note
Modified:
llvm/trunk/lib/Target/X86/README.txt
Modified: llvm/trunk/lib/Target/X86/README.txt
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/README.txt?rev=41021&r1=41020&r2=41021&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/README.txt (original)
+++ llvm/trunk/lib/Target/X86/README.txt Sat Aug 11 13:19:07 2007
@@ -559,7 +559,25 @@
//===---------------------------------------------------------------------===//
-Implement CTTZ, CTLZ with bsf and bsr.
+Implement CTTZ, CTLZ with bsf and bsr. GCC produces:
+
+int ctz_(unsigned X) { return __builtin_ctz(X); }
+int clz_(unsigned X) { return __builtin_clz(X); }
+int ffs_(unsigned X) { return __builtin_ffs(X); }
+
+_ctz_:
+ bsfl 4(%esp), %eax
+ ret
+_clz_:
+ bsrl 4(%esp), %eax
+ xorl $31, %eax
+ ret
+_ffs_:
+ movl $-1, %edx
+ bsfl 4(%esp), %eax
+ cmove %edx, %eax
+ addl $1, %eax
+ ret
//===---------------------------------------------------------------------===//
@@ -1077,8 +1095,9 @@
define <4 x float> @test1(<4 x float> %V) {
entry:
- %tmp8 = shufflevector <4 x float> %V, <4 x float> undef, <4 x i32> <
i32 3, i32 2, i32 1, i32 0 > ; <<4 x float>> [#uses=1]
- %add = add <4 x float> %tmp8, %V ; <<4 x float>>
[#uses=1]
+ %tmp8 = shufflevector <4 x float> %V, <4 x float> undef,
+ <4 x i32> < i32 3, i32 2, i32 1, i32 0
>
+ %add = add <4 x float> %tmp8, %V
ret <4 x float> %add
}
_______________________________________________
llvm-commits mailing list
llvm-commits@cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
