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

diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 034114c680c7c22075d4b1e6ec46103a4ac0e730..5a10b728d4f5fb50b1692e097e949498f9c1f39b 100644 (file)
--- 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 d4773bb5809b0def716eb6b48f3e3a5c90c32a08..63249f4cf14527043b49400e933b1eca5c5c035a 100644 (file)
--- 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
+}