From 5f6913cecd9f760c02754772cb57fa4d9a96624f Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Mon, 17 Sep 2007 14:49:27 +0000
Subject: [PATCH] Emit integer x<1 as x<=0, as comparisons with zero (now
 includeing 64-bit) can use test instead of cmp with an immediate.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42026 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/X86/X86ISelLowering.cpp | 5 +++++
 test/CodeGen/X86/cmp1.ll           | 7 +++++++
 2 files changed, 12 insertions(+)
 create mode 100644 test/CodeGen/X86/cmp1.ll

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 55f37a65846..3b4b4f91750 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -1546,6 +1546,11 @@ static bool translateX86CC(ISD::CondCode SetCCOpcode, bool isFP,
         // 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;
       }
     }
 
diff --git a/test/CodeGen/X86/cmp1.ll b/test/CodeGen/X86/cmp1.ll
new file mode 100644
index 00000000000..241618c531a
--- /dev/null
+++ b/test/CodeGen/X86/cmp1.ll
@@ -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
+}