[llvm-commits] [llvm] r153741 - /llvm/trunk/lib/Target/X86/README.txt

[Benjamin Kramer]

Author: d0k
Date: Fri Mar 30 08:02:58 2012
New Revision: 153741

URL: http://llvm.org/viewvc/llvm-project?rev=153741&view=rev
Log:
Add a note about a missed cmov -> sbb opportunity.

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=153741&r1=153740&r2=153741&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/README.txt (original)
+++ llvm/trunk/lib/Target/X86/README.txt Fri Mar 30 08:02:58 2012
@@ -2060,3 +2060,21 @@
 The trick is to match "fetch_and_add(X, -C) == C".
 
 //===---------------------------------------------------------------------===//
+
+unsigned t(unsigned a, unsigned b) {
+  return a <= b ? 5 : -5;
+}
+
+We generate:
+	movl	$5, %ecx
+	cmpl	%esi, %edi
+	movl	$-5, %eax
+	cmovbel	%ecx, %eax
+
+GCC:
+	cmpl	%edi, %esi
+	sbbl	%eax, %eax
+	andl	$-10, %eax
+	addl	$5, %eax
+
+//===---------------------------------------------------------------------===//