[llvm-commits] [llvm] r42026 - in /llvm/trunk: lib/Target/X86/X86ISelLowering.cpp test/CodeGen/X86/cmp1.ll

[Dan Gohman]

Author: djg
Date: Mon Sep 17 09:49:27 2007
New Revision: 42026

URL: http://llvm.org/viewvc/llvm-project?rev=42026&view=rev
Log:
Emit integer x<1 as x<=0, as comparisons with zero (now includeing
64-bit) can use test instead of cmp with an immediate.

Added:
    llvm/trunk/test/CodeGen/X86/cmp1.ll
Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=42026&r1=42025&r2=42026&view=diff

==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Mon Sep 17 09:49:27 2007
@@ -1546,6 +1546,11 @@
         // X < 0   -> X == 0, jump on sign.
         X86CC = X86::COND_S;
         return true;
+      } else if (SetCCOpcode == ISD::SETLT && RHSC->getValue() == 1) {
+        // X < 1   -> X <= 0
+        RHS = DAG.getConstant(0, RHS.getValueType());
+        X86CC = X86::COND_LE;
+        return true;
       }
     }
 

Added: llvm/trunk/test/CodeGen/X86/cmp1.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/cmp1.ll?rev=42026&view=auto

==============================================================================
--- llvm/trunk/test/CodeGen/X86/cmp1.ll (added)
+++ llvm/trunk/test/CodeGen/X86/cmp1.ll Mon Sep 17 09:49:27 2007
@@ -0,0 +1,7 @@
+; RUN: llvm-as < %s | llc -march=x86-64 | grep -v cmp
+
+define i64 @foo(i64 %x) {
+  %t = icmp slt i64 %x, 1
+  %r = zext i1 %t to i64
+  ret i64 %r
+}