From 3cc3283fcbb90924196cc38ee5977b35c4ee28b5 Mon Sep 17 00:00:00 2001
From: Daniel Dunbar <daniel@zuster.org>
Date: Wed, 25 Aug 2010 16:58:05 +0000
Subject: [PATCH] ARM/Thumb2: Fix a misselect in getARMCmp, when attempting to
 adjust a signed comparison that would overflow.  - The other under/overflow
 cases can't actually happen because the immediates    which would trigger
 them are legal (so we don't enter this code), but    adjusted the style to
 make it clear the transform is always valid.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112053 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMISelLowering.cpp |  8 ++++----
 test/CodeGen/Thumb2/thumb2-cmp.ll  | 14 ++++++++++++++
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 034114c680c..5a10b728d4f 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -2271,28 +2271,28 @@ ARMTargetLowering::getARMCmp(SDValue LHS, SDValue RHS, ISD::CondCode CC,
       default: break;
       case ISD::SETLT:
       case ISD::SETGE:
-        if (isLegalICmpImmediate(C-1)) {
+        if (C != 0x80000000 && isLegalICmpImmediate(C-1)) {
           CC = (CC == ISD::SETLT) ? ISD::SETLE : ISD::SETGT;
           RHS = DAG.getConstant(C-1, MVT::i32);
         }
         break;
       case ISD::SETULT:
       case ISD::SETUGE:
-        if (C > 0 && isLegalICmpImmediate(C-1)) {
+        if (C != 0 && isLegalICmpImmediate(C-1)) {
           CC = (CC == ISD::SETULT) ? ISD::SETULE : ISD::SETUGT;
           RHS = DAG.getConstant(C-1, MVT::i32);
         }
         break;
       case ISD::SETLE:
       case ISD::SETGT:
-        if (isLegalICmpImmediate(C+1)) {
+        if (C != 0x7fffffff && isLegalICmpImmediate(C+1)) {
           CC = (CC == ISD::SETLE) ? ISD::SETLT : ISD::SETGE;
           RHS = DAG.getConstant(C+1, MVT::i32);
         }
         break;
       case ISD::SETULE:
       case ISD::SETUGT:
-        if (C < 0xffffffff && isLegalICmpImmediate(C+1)) {
+        if (C != 0xffffffff && isLegalICmpImmediate(C+1)) {
           CC = (CC == ISD::SETULE) ? ISD::SETULT : ISD::SETUGE;
           RHS = DAG.getConstant(C+1, MVT::i32);
         }
diff --git a/test/CodeGen/Thumb2/thumb2-cmp.ll b/test/CodeGen/Thumb2/thumb2-cmp.ll
index d4773bb5809..63249f4cf14 100644
--- a/test/CodeGen/Thumb2/thumb2-cmp.ll
+++ b/test/CodeGen/Thumb2/thumb2-cmp.ll
@@ -39,3 +39,17 @@ define i1 @f5(i32 %a) {
     %tmp = icmp eq i32 %a, 1114112
     ret i1 %tmp
 }
+
+; Check that we don't do an invalid (a > b) --> !(a < b + 1) transform.
+;
+; CHECK: f6:
+; CHECK-NOT: cmp.w r0, #-2147483648
+; CHECK: bx lr
+define i32 @f6(i32 %a) {
+    %tmp = icmp sgt i32 %a, 2147483647
+    br i1 %tmp, label %true, label %false
+true:
+    ret i32 2
+false:
+    ret i32 0
+}
-- 
2.34.1