[llvm-commits] CVS: llvm/lib/Target/X86/README.txt

[Chris Lattner]

Changes in directory llvm/lib/Target/X86:

README.txt updated: 1.130 -> 1.131
---
Log message:

new note


---
Diffs of the changes:  (+13 -0)

 README.txt |   13 +++++++++++++
 1 files changed, 13 insertions(+)


Index: llvm/lib/Target/X86/README.txt
diff -u llvm/lib/Target/X86/README.txt:1.130 llvm/lib/Target/X86/README.txt:1.131
--- llvm/lib/Target/X86/README.txt:1.130	Tue Sep 12 22:22:10 2006
+++ llvm/lib/Target/X86/README.txt	Tue Sep 12 22:54:54 2006
@@ -45,6 +45,19 @@
 
 Another useful one would be  ~0ULL >> X and ~0ULL << X.
 
+One better solution for 1LL << x is:
+        xorl    %eax, %eax
+        xorl    %edx, %edx
+        testb   $32, %cl
+        sete    %al
+        setne   %dl
+        sall    %cl, %eax
+        sall    %cl, %edx
+
+But that requires good 8-bit subreg support.
+
+
+
 //===---------------------------------------------------------------------===//
 
 Compile this: