[AArch64] Predefine __AARCH64_CMODEL_*__ as GCC does

[mcgrathr]

Summary

Make Clang on aarch64 targets predefine __AARCH64_CMODEL_SMALL__
or __AARCH64_CMODEL_TINY__, etc. These are the names that GCC
uses for its predefines.

[mcgrathr]

update log

[mcgrathr]

Thanks! Can you land it for me?

[MaskRay]

clang/lib/Basic/Targets/AArch64.cpp

200

This can be simplified. I'll do that.

[MaskRay]

Add tests

Rebase after -mcmodel cleanups (including fc6057e34fb3b1cfbbfcd5d71ae25ba24eb3ffa3)

clang/lib/Basic/Targets/AArch64.cpp

if (getTriple().getOS() == llvm::Triple::UnknownOS &&
     Builder.defineMacro("__ELF__");
 
   // Target properties.
   if (!getTriple().isOSWindows() && getTriple().isArch64Bit()) {
     Builder.defineMacro("_LP64");
     Builder.defineMacro("__LP64__");
   }
 
+  std::string CodeModel = getTargetOpts().CodeModel;
+  if (CodeModel == "default")
+    CodeModel = "small";
+  for (auto& c : CodeModel) {
+    c = toupper(c);
+  }
+  Builder.defineMacro("__AARCH64_CMODEL_" + CodeModel + "__");
+
   // ACLE predefines. Many can only have one possible value on v8 AArch64.
   Builder.defineMacro("__ARM_ACLE", "200");
   Builder.defineMacro("__ARM_ARCH", "8");
   Builder.defineMacro("__ARM_ARCH_PROFILE", "'A'");
 
   Builder.defineMacro("__ARM_64BIT_STATE", "1");
   Builder.defineMacro("__ARM_PCS_AAPCS64", "1");
   Builder.defineMacro("__ARM_ARCH_ISA_A64", "1");

clang/test/Preprocessor/init.c

 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=aarch64-none-none < /dev/null | FileCheck -match-full-lines -check-prefix AARCH64 %s
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=arm64-none-none < /dev/null | FileCheck -match-full-lines -check-prefix AARCH64 %s
 // RUN: %clang_cc1 -x c++ -E -dM -ffreestanding -triple=arm64-none-none < /dev/null | FileCheck -match-full-lines -check-prefix AARCH64 -check-prefix AARCH64-CXX %s
 //
 // AARCH64:#define _LP64 1
 // AARCH64-NOT:#define __AARCH64EB__ 1
 // AARCH64:#define __AARCH64EL__ 1
 // AARCH64-NOT:#define __AARCH_BIG_ENDIAN 1
+// AARCH64:#define __AARCH64_CMODEL_SMALL__ 1
 // AARCH64:#define __ARM_64BIT_STATE 1
 // AARCH64:#define __ARM_ARCH 8
 // AARCH64:#define __ARM_ARCH_ISA_A64 1
 // AARCH64-NOT:#define __ARM_BIG_ENDIAN 1
 // AARCH64:#define __BIGGEST_ALIGNMENT__ 16
 // AARCH64:#define __BYTE_ORDER__ __ORDER_LITTLE_ENDIAN__
 // AARCH64:#define __CHAR16_TYPE__ unsigned short
 // AARCH64:#define __CHAR32_TYPE__ unsigned int