Allow negative immediates in ARM and Thumb2 compares.
ARM and Thumb2 mode can use cmn instructions to compare against negative
immediates. Thumb1 mode can't.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154183 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index fab3e24..c20ee67 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -8614,10 +8614,12 @@
/// a register against the immediate without having to materialize the
/// immediate into a register.
bool ARMTargetLowering::isLegalICmpImmediate(int64_t Imm) const {
+ // Thumb2 and ARM modes can use cmn for negative immediates.
if (!Subtarget->isThumb())
- return ARM_AM::getSOImmVal(Imm) != -1;
+ return ARM_AM::getSOImmVal(std::abs(Imm)) != -1;
if (Subtarget->isThumb2())
- return ARM_AM::getT2SOImmVal(Imm) != -1;
+ return ARM_AM::getT2SOImmVal(std::abs(Imm)) != -1;
+ // Thumb1 doesn't have cmn, and only 8-bit immediates.
return Imm >= 0 && Imm <= 255;
}