[llvm-commits] [llvm] r42554 - /llvm/trunk/lib/Target/X86/README.txt

[Bill Wendling]

Author: void
Date: Tue Oct  2 16:49:31 2007
New Revision: 42554

URL: http://llvm.org/viewvc/llvm-project?rev=42554&view=rev
Log:
Another micro-opt.

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=42554&r1=42553&r2=42554&view=diff

==============================================================================
--- llvm/trunk/lib/Target/X86/README.txt (original)
+++ llvm/trunk/lib/Target/X86/README.txt Tue Oct  2 16:49:31 2007
@@ -1306,3 +1306,19 @@
         movl      88(%esp), %eax                                #481.12
 
 //===---------------------------------------------------------------------===//
+
+This code:
+
+	%tmp659 = icmp slt i16 %tmp654, 0		; <i1> [#uses=1]
+	br i1 %tmp659, label %cond_true662, label %cond_next715
+
+produces this:
+
+	testw	%cx, %cx
+	movswl	%cx, %esi
+	jns	LBB4_109	# cond_next715
+
+Shark tells us that using %cx in the testw instruction is sub-optimal. It
+suggests using the 32-bit register (which is what ICC uses).
+
+//===---------------------------------------------------------------------===//