[clang] [ARM] Using cp15 while mtp =auto and arch is arm_arch6k and support thumb2 (PR #130027)

[Vladi Krapp via cfe-commits]

================
@@ -208,10 +208,17 @@ bool arm::useAAPCSForMachO(const llvm::Triple &T) {
 bool arm::isHardTPSupported(const llvm::Triple &Triple) {
   int Ver = getARMSubArchVersionNumber(Triple);
   llvm::ARM::ArchKind AK = llvm::ARM::parseArch(Triple.getArchName());
-  return Triple.isARM() || AK == llvm::ARM::ArchKind::ARMV6T2 ||
-         (Ver >= 7 && AK != llvm::ARM::ArchKind::ARMV8MBaseline);
+  return Triple.isARM() || (Ver >= 7 && AK != llvm::ARM::ArchKind::ARMV8MBaseline);
 }
 
+
+// We follow GCC mtp=auto when arch is arm_arch6k and support thumb2
+bool arm::isHardTPAndThumb2(const llvm::Triple &Triple) {
+  llvm::ARM::ArchKind AK = llvm::ARM::parseArch(Triple.getArchName());
+  return Triple.isARM() && AK >= llvm::ARM::ArchKind::ARMV6K && AK != llvm::ARM::ArchKind::ARMV8MBaseline;
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VladiKrapp-Arm wrote:

The check here is incorrect, if nothing else, the check should be '!isMProfile(Tripple)', as no M Profile chips support HardTP. 


Something along the lines of
```
  int Ver = getARMSubArchVersionNumber(Triple);
  llvm::ARM::ArchKind AK = llvm::ARM::parseArch(Triple.getArchName());
  return Triple.isARM() || AK == llvm::ARM::ArchKind::ARMV6T2 ||
         (Ver >= 7 && !isARMMProfile(Triple));

```
But maybe this should be done in the original isHardTPSupported?

https://github.com/llvm/llvm-project/pull/130027