_Float16 preprocessor macro definitions

[SjoerdMeijer]

Summary

This adds the _Float16 preprocessor macro definitions.

[rogfer01]

lib/Headers/float.h

146

My understanding is that, given that we support TS18661-2 by default, this macro should be predefined by clang and then there is no need to protect these macros.

You may want to add a test for this in test/Preprocessor/init.c.

148–151

There is a typo here, these macros should start with __FLT16_. Add a test for these names test/Headers/float.c.

[scanon]

lib/Headers/float.h

146

Where do you see that the __STDC_WANT_IEC_60559_TYPES_EXT__ macro should be predefined by clang?

[rogfer01]

lib/Headers/float.h

146

Hi Steve,

certainly you're right, the TS says

The new identifiers added to C11 library headers by this part of ISO/IEC TS-18661 are defined or declared by their respective headers only if __STDC_WANT_IEC_60559_TYPES_EXT__ is defined as a macro at the point in the source file where the appropriate header is first included.

so (if I read this right) these identifiers are only available if such macro is defined when including float.h.

Can I assume from your comment that someone else should define it? Perhaps the float.h header itself, some other file in the C-library implementation or the user of the compiler via some -D__STDC_WANT_IEC_60559_TYPES_EXT__, but not be predefined by the compiler? If this is the case, then the macros still have to be guarded conditionally (as they were in the original patch).

Does this make sense? Thanks.

[scanon]

lib/Headers/float.h

146

I think we could justify defining it ourselves under non-strict compilation modes; alternatively, system headers might define it for users in non-strict modes.

My reading of the TS is that in strict mode, these types and macros should be hidden unless the user explicitly requests them by defining __STDC_WANT_IEC_60559_TYPES_EXT__ themselves.

[SjoerdMeijer]

lib/Headers/float.h

146

Thanks, very useful discussion and clarification. I will add some tests for this, which I indeed forgot. Cheers.

[SjoerdMeijer]

Fixed the typos, and added tests.

[rogfer01]

This LGTM, but wait a couple of days before comitting in case @rsmith or @scanon (or others!) have further comments.

[scanon]

LGTM as well.

[SjoerdMeijer]

many thanks for reviewing and your help.

lib/Frontend/InitPreprocessor.cpp

if (OriginalFile.empty())
     return;
 
   AddImplicitInclude(Builder, OriginalFile);
 }
 
 /// PickFP - This is used to pick a value based on the FP semantics of the
 /// specified FP model.
 template <typename T>
-static T PickFP(const llvm::fltSemantics *Sem, T IEEESingleVal,
+static T PickFP(const llvm::fltSemantics *Sem, T IEEEHalfVal, T IEEESingleVal,
                 T IEEEDoubleVal, T X87DoubleExtendedVal, T PPCDoubleDoubleVal,
                 T IEEEQuadVal) {
+  if (Sem == (const llvm::fltSemantics*)&llvm::APFloat::IEEEhalf())
+    return IEEEHalfVal;
   if (Sem == (const llvm::fltSemantics*)&llvm::APFloat::IEEEsingle())
     return IEEESingleVal;
   if (Sem == (const llvm::fltSemantics*)&llvm::APFloat::IEEEdouble())
     return IEEEDoubleVal;
   if (Sem == (const llvm::fltSemantics*)&llvm::APFloat::x87DoubleExtended())
     return X87DoubleExtendedVal;
   if (Sem == (const llvm::fltSemantics*)&llvm::APFloat::PPCDoubleDouble())
     return PPCDoubleDoubleVal;
   assert(Sem == (const llvm::fltSemantics*)&llvm::APFloat::IEEEquad());
   return IEEEQuadVal;
 }
 
 static void DefineFloatMacros(MacroBuilder &Builder, StringRef Prefix,
                               const llvm::fltSemantics *Sem, StringRef Ext) {
   const char *DenormMin, *Epsilon, *Max, *Min;
-  DenormMin = PickFP(Sem, "1.40129846e-45", "4.9406564584124654e-324",
-                     "3.64519953188247460253e-4951",
+  DenormMin = PickFP(Sem, "5.9604644775390625e-8", "1.40129846e-45",
+                     "4.9406564584124654e-324", "3.64519953188247460253e-4951",
                      "4.94065645841246544176568792868221e-324",
                      "6.47517511943802511092443895822764655e-4966");
-  int Digits = PickFP(Sem, 6, 15, 18, 31, 33);
-  int DecimalDigits = PickFP(Sem, 9, 17, 21, 33, 36);
-  Epsilon = PickFP(Sem, "1.19209290e-7", "2.2204460492503131e-16",
-                   "1.08420217248550443401e-19",
+  int Digits = PickFP(Sem, 3, 6, 15, 18, 31, 33);
+  int DecimalDigits = PickFP(Sem, 5, 9, 17, 21, 33, 36);
+  Epsilon = PickFP(Sem, "9.765625e-4", "1.19209290e-7",
+                   "2.2204460492503131e-16", "1.08420217248550443401e-19",
                    "4.94065645841246544176568792868221e-324",
                    "1.92592994438723585305597794258492732e-34");
-  int MantissaDigits = PickFP(Sem, 24, 53, 64, 106, 113);
-  int Min10Exp = PickFP(Sem, -37, -307, -4931, -291, -4931);
-  int Max10Exp = PickFP(Sem, 38, 308, 4932, 308, 4932);
-  int MinExp = PickFP(Sem, -125, -1021, -16381, -968, -16381);
-  int MaxExp = PickFP(Sem, 128, 1024, 16384, 1024, 16384);
-  Min = PickFP(Sem, "1.17549435e-38", "2.2250738585072014e-308",
+  int MantissaDigits = PickFP(Sem, 11, 24, 53, 64, 106, 113);
+  int Min10Exp = PickFP(Sem, -13, -37, -307, -4931, -291, -4931);
+  int Max10Exp = PickFP(Sem, 4, 38, 308, 4932, 308, 4932);
+  int MinExp = PickFP(Sem, -14, -125, -1021, -16381, -968, -16381);
+  int MaxExp = PickFP(Sem, 15, 128, 1024, 16384, 1024, 16384);
+  Min = PickFP(Sem, "6.103515625e-5", "1.17549435e-38", "2.2250738585072014e-308",
                "3.36210314311209350626e-4932",
                "2.00416836000897277799610805135016e-292",
                "3.36210314311209350626267781732175260e-4932");
-  Max = PickFP(Sem, "3.40282347e+38", "1.7976931348623157e+308",
+  Max = PickFP(Sem, "6.5504e+4", "3.40282347e+38", "1.7976931348623157e+308",
                "1.18973149535723176502e+4932",
                "1.79769313486231580793728971405301e+308",
                "1.18973149535723176508575932662800702e+4932");
 
   SmallString<32> DefPrefix;
   DefPrefix = "__";
   DefPrefix += Prefix;
   DefPrefix += "_";
#undef TOSTR2
   DefineType("__CHAR16_TYPE__", TI.getChar16Type(), Builder);
   DefineType("__CHAR32_TYPE__", TI.getChar32Type(), Builder);
 
   DefineTypeWidth("__UINTMAX_WIDTH__",  TI.getUIntMaxType(), TI, Builder);
   DefineType("__UINTPTR_TYPE__", TI.getUIntPtrType(), Builder);
   DefineFmt("__UINTPTR", TI.getUIntPtrType(), TI, Builder);
   DefineTypeWidth("__UINTPTR_WIDTH__", TI.getUIntPtrType(), TI, Builder);
 
+  DefineFloatMacros(Builder, "FLT16", &TI.getHalfFormat(), "F16");
   DefineFloatMacros(Builder, "FLT", &TI.getFloatFormat(), "F");
   DefineFloatMacros(Builder, "DBL", &TI.getDoubleFormat(), "");
   DefineFloatMacros(Builder, "LDBL", &TI.getLongDoubleFormat(), "L");
 
   // Define a __POINTER_WIDTH__ macro for stdint.h.
   Builder.defineMacro("__POINTER_WIDTH__",
                       Twine((int)TI.getPointerWidth(0)));
 

lib/Headers/float.h

 #  define FLT_TRUE_MIN __FLT_DENORM_MIN__
 #  define DBL_TRUE_MIN __DBL_DENORM_MIN__
 #  define LDBL_TRUE_MIN __LDBL_DENORM_MIN__
 #  define FLT_DECIMAL_DIG __FLT_DECIMAL_DIG__
 #  define DBL_DECIMAL_DIG __DBL_DECIMAL_DIG__
 #  define LDBL_DECIMAL_DIG __LDBL_DECIMAL_DIG__
 #endif
 
+#ifdef __STDC_WANT_IEC_60559_TYPES_EXT__
+#  define FLT16_MANT_DIG    __FLT16_MANT_DIG__
+#  define FLT16_DECIMAL_DIG __FLT16_DECIMAL_DIG__
+#  define FLT16_DIG         __FLT16_DIG__
+#  define FLT16_MIN_EXP     __FLT16_MIN_EXP__
+#  define FLT16_MIN_10_EXP  __FLT16_MIN_10_EXP__
+#  define FLT16_MAX_EXP     __FLT16_MAX_EXP__
+#  define FLT16_MAX_10_EXP  __FLT16_MAX_10_EXP__
+#  define FLT16_MAX         __FLT16_MAX__
+#  define FLT16_EPSILON     __FLT16_EPSILON__
+#  define FLT16_MIN         __FLT16_MIN__
+#  define FLT16_TRUE_MIN    __FLT16_TRUE_MIN__
+#endif /* __STDC_WANT_IEC_60559_TYPES_EXT__ */
+
 #endif /* __FLOAT_H */

test/Headers/float16.c

+// RUN: %clang_cc1 -fsyntax-only -verify -std=c89 -ffreestanding %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c99 -ffreestanding %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c11 -ffreestanding %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 -x c++ -ffreestanding %s
+// expected-no-diagnostics
+
+#define __STDC_WANT_IEC_60559_TYPES_EXT__
+#include <float.h>
+
+#ifndef FLT16_MIN_10_EXP
+    #error "Macro FLT16_MIN_10_EXP is missing."
+#elif   FLT16_MIN_10_EXP > -13
+    #error "Macro FLT16_MIN_10_EXP is invalid."
+#endif
+
+_Static_assert(FLT16_MIN_10_EXP == __FLT16_MIN_10_EXP__, "");
+
+#ifndef FLT16_MIN_EXP
+    #error "Macro FLT16_MIN_EXP is missing."
+#elif   FLT16_MIN_EXP > -14
+    #error "Macro FLT16_MIN_EXP is invalid."
+#endif
+
+_Static_assert(FLT16_MIN_EXP == __FLT16_MIN_EXP__, "");
+
+#ifndef FLT16_MAX_10_EXP
+    #error "Macro FLT16_MAX_10_EXP is missing."
+#elif   FLT16_MAX_10_EXP < 4
+    #error "Macro FLT16_MAX_10_EXP is invalid."
+#endif
+
+_Static_assert(FLT16_MAX_10_EXP == __FLT16_MAX_10_EXP__, "");
+
+#ifndef FLT16_MAX_EXP
+    #error "Macro FLT16_MAX_EXP is missing."
+#elif   FLT16_MAX_EXP < 15
+    #error "Macro FLT16_MAX_EXP is invalid."
+#endif
+
+_Static_assert(FLT16_MAX_EXP == __FLT16_MAX_EXP__, "");
+
+#ifndef FLT16_DECIMAL_DIG
+    #error "Macro FLT16_DECIMAL_DIG is missing."
+#elif   FLT16_DECIMAL_DIG < 5
+    #error "Macro FLT16_DECIMAL_DIG is invalid."
+#endif
+
+_Static_assert(FLT16_DECIMAL_DIG == __FLT16_DECIMAL_DIG__, "");
+
+#ifndef FLT16_DIG
+    #error "Macro FLT16_DIG is missing."
+#elif   FLT16_DIG < 3
+    #error "Macro FLT16_DIG is invalid."
+#endif
+
+_Static_assert(FLT16_DIG == __FLT16_DIG__, "");
+
+#ifndef FLT16_MANT_DIG
+    #error "Macro FLT16_MANT_DIG is missing."
+#elif   FLT16_MANT_DIG < 11
+    #error "Macro FLT16_MANT_DIG is invalid."
+#endif
+
+_Static_assert(FLT16_MANT_DIG == __FLT16_MANT_DIG__, "");
+

test/Preprocessor/init.c

 // AARCH64:#define __DBL_MANT_DIG__ 53
 // AARCH64:#define __DBL_MAX_10_EXP__ 308
 // AARCH64:#define __DBL_MAX_EXP__ 1024
 // AARCH64:#define __DBL_MAX__ 1.7976931348623157e+308
 // AARCH64:#define __DBL_MIN_10_EXP__ (-307)
 // AARCH64:#define __DBL_MIN_EXP__ (-1021)
 // AARCH64:#define __DBL_MIN__ 2.2250738585072014e-308
 // AARCH64:#define __DECIMAL_DIG__ __LDBL_DECIMAL_DIG__
+// AARCH64:#define __FLT16_DECIMAL_DIG__ 5
+// AARCH64:#define __FLT16_DENORM_MIN__ 5.9604644775390625e-8F16
+// AARCH64:#define __FLT16_DIG__ 3
+// AARCH64:#define __FLT16_EPSILON__ 9.765625e-4F16
+// AARCH64:#define __FLT16_HAS_DENORM__ 1
+// AARCH64:#define __FLT16_HAS_INFINITY__ 1
+// AARCH64:#define __FLT16_HAS_QUIET_NAN__ 1
+// AARCH64:#define __FLT16_MANT_DIG__ 11
+// AARCH64:#define __FLT16_MAX_10_EXP__ 4
+// AARCH64:#define __FLT16_MAX_EXP__ 15
+// AARCH64:#define __FLT16_MAX__ 6.5504e+4F16
+// AARCH64:#define __FLT16_MIN_10_EXP__ (-13)
+// AARCH64:#define __FLT16_MIN_EXP__ (-14)
+// AARCH64:#define __FLT16_MIN__ 6.103515625e-5F16
 // AARCH64:#define __FLT_DENORM_MIN__ 1.40129846e-45F
 // AARCH64:#define __FLT_DIG__ 6
 // AARCH64:#define __FLT_EPSILON__ 1.19209290e-7F
 // AARCH64:#define __FLT_EVAL_METHOD__ 0
 // AARCH64:#define __FLT_HAS_DENORM__ 1
 // AARCH64:#define __FLT_HAS_INFINITY__ 1
 // AARCH64:#define __FLT_HAS_QUIET_NAN__ 1
 // AARCH64:#define __FLT_MANT_DIG__ 24

 // WEBASSEMBLY32-NEXT:#define __DBL_MAX_EXP__ 1024
 // WEBASSEMBLY32-NEXT:#define __DBL_MAX__ 1.7976931348623157e+308
 // WEBASSEMBLY32-NEXT:#define __DBL_MIN_10_EXP__ (-307)
 // WEBASSEMBLY32-NEXT:#define __DBL_MIN_EXP__ (-1021)
 // WEBASSEMBLY32-NEXT:#define __DBL_MIN__ 2.2250738585072014e-308
 // WEBASSEMBLY32-NEXT:#define __DECIMAL_DIG__ __LDBL_DECIMAL_DIG__
 // WEBASSEMBLY32-NOT:#define __ELF__
 // WEBASSEMBLY32-NEXT:#define __FINITE_MATH_ONLY__ 0
-// WEBASSEMBLY32-NEXT:#define __FLT_DECIMAL_DIG__ 9
+// WEBASSEMBLY32:#define __FLT_DECIMAL_DIG__ 9
 // WEBASSEMBLY32-NEXT:#define __FLT_DENORM_MIN__ 1.40129846e-45F
 // WEBASSEMBLY32-NEXT:#define __FLT_DIG__ 6
 // WEBASSEMBLY32-NEXT:#define __FLT_EPSILON__ 1.19209290e-7F
 // WEBASSEMBLY32-NEXT:#define __FLT_EVAL_METHOD__ 0
 // WEBASSEMBLY32-NEXT:#define __FLT_HAS_DENORM__ 1
 // WEBASSEMBLY32-NEXT:#define __FLT_HAS_INFINITY__ 1
 // WEBASSEMBLY32-NEXT:#define __FLT_HAS_QUIET_NAN__ 1
 // WEBASSEMBLY32-NEXT:#define __FLT_MANT_DIG__ 24

 // WEBASSEMBLY64-NEXT:#define __DBL_MAX_EXP__ 1024
 // WEBASSEMBLY64-NEXT:#define __DBL_MAX__ 1.7976931348623157e+308
 // WEBASSEMBLY64-NEXT:#define __DBL_MIN_10_EXP__ (-307)
 // WEBASSEMBLY64-NEXT:#define __DBL_MIN_EXP__ (-1021)
 // WEBASSEMBLY64-NEXT:#define __DBL_MIN__ 2.2250738585072014e-308
 // WEBASSEMBLY64-NEXT:#define __DECIMAL_DIG__ __LDBL_DECIMAL_DIG__
 // WEBASSEMBLY64-NOT:#define __ELF__
 // WEBASSEMBLY64-NEXT:#define __FINITE_MATH_ONLY__ 0
-// WEBASSEMBLY64-NEXT:#define __FLT_DECIMAL_DIG__ 9
+// WEBASSEMBLY64:#define __FLT_DECIMAL_DIG__ 9
 // WEBASSEMBLY64-NEXT:#define __FLT_DENORM_MIN__ 1.40129846e-45F
 // WEBASSEMBLY64-NEXT:#define __FLT_DIG__ 6
 // WEBASSEMBLY64-NEXT:#define __FLT_EPSILON__ 1.19209290e-7F
 // WEBASSEMBLY64-NEXT:#define __FLT_EVAL_METHOD__ 0
 // WEBASSEMBLY64-NEXT:#define __FLT_HAS_DENORM__ 1
 // WEBASSEMBLY64-NEXT:#define __FLT_HAS_INFINITY__ 1
 // WEBASSEMBLY64-NEXT:#define __FLT_HAS_QUIET_NAN__ 1
 // WEBASSEMBLY64-NEXT:#define __FLT_MANT_DIG__ 24