From: Benjamin Kramer <benny.kra@googlemail.com>
Date: Fri, 30 Mar 2012 13:02:58 +0000 (+0000)
Subject: Add a note about a missed cmov -> sbb opportunity.
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=2f1abe9a5f2f7c4c1b66099b50b7f4095b3f93f8;p=oota-llvm.git

Add a note about a missed cmov -> sbb opportunity.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153741 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt
index f9c1d357432..6a8a4fdf252 100644
--- a/lib/Target/X86/README.txt
+++ b/lib/Target/X86/README.txt
@@ -2060,3 +2060,21 @@ Instead we could generate:
 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
+
+//===---------------------------------------------------------------------===//