[PowerPC] [Clang] Define macros to identify quad-fp semantics

[qiucf]

Summary

We have option -mabi=ieeelongdouble to set current long double to IEEEquad semantics. Like what GCC does, we need to define __LONG_DOUBLE_IEEE128__ macro in this case, and __LONG_DOUBLE_IBM128__ if using PPCDoubleDouble.

[qiucf]

Remove FIXME

[steven.zhang]

clang/lib/Basic/Targets/PPC.cpp

123

Can you please double check if we need to define these two macros if PPC IEEE long double enabled ? And also double check if they can be controlled by options.

[steven.zhang]

Sorry, accept the revision by mistake. Please hold on until my comments addressed.

[qiucf]

clang/lib/Basic/Targets/PPC.cpp

123

Yes. GCC shows expected behavior that __LONG_DOUBLE_IEEE128__ is defined under -mabi=ieeelongdouble while __LONG_DOUBLE_IBM128__ is defined when not. Some libraries may rely on this macro. (see https://www.openwall.com/lists/musl/2019/06/30/8)

In clang, currently we can only use __LDBL_MANT_DIG__ to guess current 128-bit fp semantics. (106 for IBM-quad, 113 for IEEE-quad). We need to implement dedicated macros.

And I'll keep the FIXME since it's not related to this revision.

[qiucf]

Keep the FIXME.

[steven.zhang]

LGTM now and thank you for the double check. But please hold on for some days in case someone has concern on enabling the new macros(we are enabling the LONG_DOUBLE_IBM128 by default now).

clang/lib/Basic/Targets/PPC.cpp

void PPCTargetInfo::getTargetDefines(const LangOptions &Opts,
   // Subtarget options.
   if (!getTriple().isOSAIX()){
     Builder.defineMacro("__NATURAL_ALIGNMENT__");
   }
   Builder.defineMacro("__REGISTER_PREFIX__", "");
 
   // FIXME: Should be controlled by command line option.
   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__");
   }
 
   // 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)

clang/test/CodeGen/ppc64-long-double.cpp

 // RUN:   -mabi=ieeelongdouble | FileCheck --check-prefix=FP128 %s
 
 // IBM extended double is the default.
 // RUN: %clang_cc1 -triple powerpc64-linux-gnu -emit-llvm -o - %s | \
 // RUN:   FileCheck --check-prefix=IBM128 %s
 // RUN: %clang_cc1 -triple powerpc64-linux-musl -emit-llvm -o - -mlong-double-128 %s | \
 // RUN:   FileCheck --check-prefix=IBM128 %s
 
+// Check IBM-quad and IEEE-quad macros are defined.
+// RUN: %clang -E -dM -ffreestanding -target powerpc64le-linux-gnu %s \
+// RUN:   -mabi=ibmlongdouble | FileCheck -check-prefix=CHECK-DEF-IBM128 %s
+// RUN: %clang -E -dM -ffreestanding -target powerpc64le-linux-gnu %s \
+// RUN:   -mabi=ieeelongdouble | FileCheck -check-prefix=CHECK-DEF-IEEE128 %s
+// RUN: %clang -E -dM -ffreestanding -target powerpc64le-linux-gnu %s \
+// RUN:   -mlong-double-64 | FileCheck -check-prefix=CHECK-DEF-F64 %s
+
+// CHECK-DEF-IBM128: #define __LONG_DOUBLE_128__
+// CHECK-DEF-IBM128: #define __LONG_DOUBLE_IBM128__
+// CHECK-DEF-IEEE128: #define __LONG_DOUBLE_128__
+// CHECK-DEF-IEEE128: #define __LONG_DOUBLE_IEEE128__
+// CHECK-DEF-F64-NOT: #define __LONG_DOUBLE_128__
+
 long double x = 0;
 int size = sizeof(x);
 
 // FP64: @x = global double {{.*}}, align 8
 // FP64: @size = global i32 8
 // FP128: @x = global fp128 {{.*}}, align 16
 // FP128: @size = global i32 16
 // IBM128: @x = global ppc_fp128 {{.*}}, align 16
 // IBM128: @size = global i32 16
 
 long double foo(long double d) { return d; }
 
 // FP64: double @_Z3fooe(double %d)
 // FP128: fp128 @_Z3foou9__ieee128(fp128 %d)
 // IBM128: ppc_fp128 @_Z3foog(ppc_fp128 %d)