_LP64 macro set incorrectly in clang/lib/Basic/Targets/AArch64.cpp

[NickLewisL3H]

The _LP64 macro is set in clang/lib/Basic/Targets/AArch64.cpp

n_lewis@a009906:~/llvm-project$ tail +225 clang/lib/Basic/Targets/AArch64.cpp | head -5
  // Target properties.
  if (!getTriple().isOSWindows() && getTriple().isArch64Bit()) {
    Builder.defineMacro("_LP64");
    Builder.defineMacro("__LP64__");
  }

I think this is incorrect for two reasons:

1. The setting of _LP64 is the responsibility of clang/lib/Frontend/InitPreprocessor.cpp
2. The AArch64.cpp code does not check that pointers and longs are actually 64-bits. For example AArch64 Morello has 128-bit pointers

[jrtc27]

Well, the latter is only for the Morello downstream fork as all supported AArch64 variants upstream work for this, but the code does seem unnecessary given the generic code in InitPreprocessor checks precisely for I32 (that one's a bit dubious, should probably just be < 64, but eh, 16-bit ints with 64-bit longs and pointers would be a weird target that most real-world code would hate), L64 and P64. Deleting it should be NFC upstream and fix the issue downstream.

[llvmbot]

@llvm/issue-subscribers-clang-driver

[llvmbot]

@llvm/issue-subscribers-backend-aarch64