[llvm] r291097 - [GlobalISel] Fix AArch64 ICMP instruction selection

[Kristof Beyls via llvm-commits]

Author: kbeyls
Date: Thu Jan  5 04:16:08 2017
New Revision: 291097

URL: http://llvm.org/viewvc/llvm-project?rev=291097&view=rev
Log:
[GlobalISel] Fix AArch64 ICMP instruction selection

Differential Revision: https://reviews.llvm.org/D28175


Modified:
    llvm/trunk/lib/Target/AArch64/AArch64InstructionSelector.cpp
    llvm/trunk/test/CodeGen/AArch64/GlobalISel/arm64-instructionselect.mir

Modified: llvm/trunk/lib/Target/AArch64/AArch64InstructionSelector.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64InstructionSelector.cpp?rev=291097&r1=291096&r2=291097&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64InstructionSelector.cpp (original)
+++ llvm/trunk/lib/Target/AArch64/AArch64InstructionSelector.cpp Thu Jan  5 04:16:08 2017
@@ -1071,8 +1071,12 @@ bool AArch64InstructionSelector::select(
       return false;
     }
 
-    const AArch64CC::CondCode CC = changeICMPPredToAArch64CC(
-        (CmpInst::Predicate)I.getOperand(1).getPredicate());
+    // CSINC increments the result by one when the condition code is false.
+    // Therefore, we have to invert the predicate to get an increment by 1 when
+    // the predicate is true.
+    const AArch64CC::CondCode invCC =
+        changeICMPPredToAArch64CC(CmpInst::getInversePredicate(
+            (CmpInst::Predicate)I.getOperand(1).getPredicate()));
 
     MachineInstr &CmpMI = *BuildMI(MBB, I, I.getDebugLoc(), TII.get(CmpOpc))
                                .addDef(ZReg)
@@ -1084,7 +1088,7 @@ bool AArch64InstructionSelector::select(
              .addDef(I.getOperand(0).getReg())
              .addUse(AArch64::WZR)
              .addUse(AArch64::WZR)
-             .addImm(CC);
+             .addImm(invCC);
 
     constrainSelectedInstRegOperands(CmpMI, TII, TRI, RBI);
     constrainSelectedInstRegOperands(CSetMI, TII, TRI, RBI);

Modified: llvm/trunk/test/CodeGen/AArch64/GlobalISel/arm64-instructionselect.mir
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/GlobalISel/arm64-instructionselect.mir?rev=291097&r1=291096&r2=291097&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/GlobalISel/arm64-instructionselect.mir (original)
+++ llvm/trunk/test/CodeGen/AArch64/GlobalISel/arm64-instructionselect.mir Thu Jan  5 04:16:08 2017
@@ -2836,13 +2836,13 @@ registers:
 
 # CHECK:  body:
 # CHECK:    %wzr = SUBSWrr %0, %0, implicit-def %nzcv
-# CHECK:    %1 = CSINCWr %wzr, %wzr, 0, implicit %nzcv
+# CHECK:    %1 = CSINCWr %wzr, %wzr, 1, implicit %nzcv
 
 # CHECK:    %xzr = SUBSXrr %2, %2, implicit-def %nzcv
-# CHECK:    %3 = CSINCWr %wzr, %wzr, 2, implicit %nzcv
+# CHECK:    %3 = CSINCWr %wzr, %wzr, 3, implicit %nzcv
 
 # CHECK:    %xzr = SUBSXrr %4, %4, implicit-def %nzcv
-# CHECK:    %5 = CSINCWr %wzr, %wzr, 1, implicit %nzcv
+# CHECK:    %5 = CSINCWr %wzr, %wzr, 0, implicit %nzcv
 
 body:             |
   bb.0: