[AIX] Define __LONGDOUBLE64 macro

[Jake-Egan]

Summary

This patch defines the macro __LONGDOUBLE64 for AIX when long double is 8 bytes.

[cebowleratibm]

clang/lib/Basic/Targets/PPC.cpp

175

I suggest querying the -mlong-double-64 option and asserting that the LongDoubleWidth is 64.

[Jake-Egan]

Add control by -mlong-double-64 option.

[cebowleratibm]

The change made me think we should add the negative test with -mlong-double-128, but then I thought we should probably make that an error until we've sorted through the AIX binary compat implications and tested it. So the patch you've proposed makes sense to me and we should follow up with handling for mlong-double-128.

[cebowleratibm]

The decision was made to make -mlong-double-128 an error on AIX: https://reviews.llvm.org/D106074 [AIX] Clang's library integration support for 128-bit long double is incomplete on AIX.

So I think your patch is ready to land. LGTM.

clang/lib/Basic/Targets/PPC.cpp

if (LongDoubleWidth == 128) {
     Builder.defineMacro("__LONG_DOUBLE_128__");
     Builder.defineMacro("__LONGDOUBLE128");
     if (Opts.PPCIEEELongDouble)
       Builder.defineMacro("__LONG_DOUBLE_IEEE128__");
     else
       Builder.defineMacro("__LONG_DOUBLE_IBM128__");
   }
 
+  if (getTriple().isOSAIX() && Opts.LongDoubleSize == 64) {
+    assert(LongDoubleWidth == 64);
+    Builder.defineMacro("__LONGDOUBLE64");
+  }
+
   // Define this for elfv2 (64-bit only) or 64-bit darwin.
   if (ABI == "elfv2" ||
       (getTriple().getOS() == llvm::Triple::Darwin && PointerWidth == 64))
     Builder.defineMacro("__STRUCT_PARM_ALIGN__", "16");
 
   if (ArchDefs & ArchDefineName)
     Builder.defineMacro(Twine("_ARCH_", StringRef(CPU).upper()));
   if (ArchDefs & ArchDefinePpcgr)

clang/test/Preprocessor/init-ppc.c

 // RUN: %clang_cc1 -x c -std=c17 -E -dM -ffreestanding -triple=powerpc-ibm-aix7.1.0.0 -fno-signed-char < /dev/null | FileCheck -match-full-lines -check-prefix PPC-AIX-STDC %s
 // PPC-AIX-STDC:#define __STDC_NO_ATOMICS__ 1
 // PPC-AIX-STDC:#define __STDC_NO_THREADS__ 1
 
 // RUN: %clang_cc1 -x c -std=c99 -E -dM -ffreestanding -triple=powerpc-ibm-aix7.1.0.0 -fno-signed-char < /dev/null | FileCheck -match-full-lines -check-prefix PPC-AIX-STDC-N %s
 // PPC-AIX-STDC-N-NOT:#define __STDC_NO_ATOMICS__ 1
 // PPC-AIX-STDC-N-NOT:#define __STDC_NO_THREADS__ 1
 
+// RUN: %clang_cc1 -E -dM -ffreestanding -triple=powerpc-ibm-aix7.1.0.0 -mlong-double-64 < /dev/null | FileCheck -match-full-lines -check-prefix PPC-AIX-LD64 %s
+// PPC-AIX-LD64:#define __LONGDOUBLE64 1
+
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=powerpc-unknown-linux-gnu -fno-signed-char < /dev/null | FileCheck -match-full-lines -check-prefix PPC-LINUX %s
 //
 // PPC-LINUX:#define _ARCH_PPC 1
 // PPC-LINUX:#define _BIG_ENDIAN 1
 // PPC-LINUX-NOT:#define _LP64
 // PPC-LINUX:#define __BIGGEST_ALIGNMENT__ 16
 // PPC-LINUX:#define __BIG_ENDIAN__ 1
 // PPC-LINUX:#define __BYTE_ORDER__ __ORDER_BIG_ENDIAN__