Support the *_WIDTH macros in limits.h and stdint.h

This completes the implementation of
WG14 N2412 (http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2412.pdf),
which standardizes C on a twos complement representation for integer
types. The only work that remained there was to define the correct
macros in the standard headers, which this patch does.

1 files changed, 49 insertions, 22 deletions

diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index ec40170..a9023a7 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -194,7 +194,7 @@ static void DefineType(const Twine &MacroName, TargetInfo::IntType Ty,
   Builder.defineMacro(MacroName, TargetInfo::getTypeName(Ty));
 }
 
-static void DefineTypeWidth(StringRef MacroName, TargetInfo::IntType Ty,
+static void DefineTypeWidth(const Twine &MacroName, TargetInfo::IntType Ty,
                             const TargetInfo &TI, MacroBuilder &Builder) {
   Builder.defineMacro(MacroName, Twine(TI.getTypeWidth(Ty)));
 }
@@ -205,6 +205,16 @@ static void DefineTypeSizeof(StringRef MacroName, unsigned BitWidth,
                       Twine(BitWidth / TI.getCharWidth()));
 }
 
+// This will generate a macro based on the prefix with `_MAX__` as the suffix
+// for the max value representable for the type, and a macro with a `_WIDTH__`
+// suffix for the width of the type.
+static void DefineTypeSizeAndWidth(const Twine &Prefix, TargetInfo::IntType Ty,
+                                   const TargetInfo &TI,
+                                   MacroBuilder &Builder) {
+  DefineTypeSize(Prefix + "_MAX__", Ty, TI, Builder);
+  DefineTypeWidth(Prefix + "_WIDTH__", Ty, TI, Builder);
+}
+
 static void DefineExactWidthIntType(TargetInfo::IntType Ty,
                                     const TargetInfo &TI,
                                     MacroBuilder &Builder) {
@@ -241,6 +251,8 @@ static void DefineExactWidthIntTypeSize(TargetInfo::IntType Ty,
   if (TypeWidth == 64)
     Ty = IsSigned ? TI.getInt64Type() : TI.getUInt64Type();
 
+  // We don't need to define a _WIDTH macro for the exact-width types because
+  // we already know the width.
   const char *Prefix = IsSigned ? "__INT" : "__UINT";
   DefineTypeSize(Prefix + Twine(TypeWidth) + "_MAX__", Ty, TI, Builder);
 }
@@ -254,7 +266,12 @@ static void DefineLeastWidthIntType(unsigned TypeWidth, bool IsSigned,
 
   const char *Prefix = IsSigned ? "__INT_LEAST" : "__UINT_LEAST";
   DefineType(Prefix + Twine(TypeWidth) + "_TYPE__", Ty, Builder);
-  DefineTypeSize(Prefix + Twine(TypeWidth) + "_MAX__", Ty, TI, Builder);
+  // We only want the *_WIDTH macro for the signed types to avoid too many
+  // predefined macros (the unsigned width and the signed width are identical.)
+  if (IsSigned)
+    DefineTypeSizeAndWidth(Prefix + Twine(TypeWidth), Ty, TI, Builder);
+  else
+    DefineTypeSize(Prefix + Twine(TypeWidth) + "_MAX__", Ty, TI, Builder);
   DefineFmt(Prefix + Twine(TypeWidth), Ty, TI, Builder);
 }
 
@@ -268,8 +285,12 @@ static void DefineFastIntType(unsigned TypeWidth, bool IsSigned,
 
   const char *Prefix = IsSigned ? "__INT_FAST" : "__UINT_FAST";
   DefineType(Prefix + Twine(TypeWidth) + "_TYPE__", Ty, Builder);
-  DefineTypeSize(Prefix + Twine(TypeWidth) + "_MAX__", Ty, TI, Builder);
-
+  // We only want the *_WIDTH macro for the signed types to avoid too many
+  // predefined macros (the unsigned width and the signed width are identical.)
+  if (IsSigned)
+    DefineTypeSizeAndWidth(Prefix + Twine(TypeWidth), Ty, TI, Builder);
+  else
+    DefineTypeSize(Prefix + Twine(TypeWidth) + "_MAX__", Ty, TI, Builder);
   DefineFmt(Prefix + Twine(TypeWidth), Ty, TI, Builder);
 }
 
@@ -887,20 +908,26 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
   assert(TI.getCharWidth() == 8 && "Only support 8-bit char so far");
   Builder.defineMacro("__CHAR_BIT__", Twine(TI.getCharWidth()));
 
+  Builder.defineMacro("__BOOL_WIDTH__", Twine(TI.getBoolWidth()));
+  Builder.defineMacro("__SHRT_WIDTH__", Twine(TI.getShortWidth()));
+  Builder.defineMacro("__INT_WIDTH__", Twine(TI.getIntWidth()));
+  Builder.defineMacro("__LONG_WIDTH__", Twine(TI.getLongWidth()));
+  Builder.defineMacro("__LLONG_WIDTH__", Twine(TI.getLongLongWidth()));
+
   DefineTypeSize("__SCHAR_MAX__", TargetInfo::SignedChar, TI, Builder);
   DefineTypeSize("__SHRT_MAX__", TargetInfo::SignedShort, TI, Builder);
   DefineTypeSize("__INT_MAX__", TargetInfo::SignedInt, TI, Builder);
   DefineTypeSize("__LONG_MAX__", TargetInfo::SignedLong, TI, Builder);
   DefineTypeSize("__LONG_LONG_MAX__", TargetInfo::SignedLongLong, TI, Builder);
-  DefineTypeSize("__WCHAR_MAX__", TI.getWCharType(), TI, Builder);
-  DefineTypeSize("__WINT_MAX__", TI.getWIntType(), TI, Builder);
-  DefineTypeSize("__INTMAX_MAX__", TI.getIntMaxType(), TI, Builder);
-  DefineTypeSize("__SIZE_MAX__", TI.getSizeType(), TI, Builder);
+  DefineTypeSizeAndWidth("__WCHAR", TI.getWCharType(), TI, Builder);
+  DefineTypeSizeAndWidth("__WINT", TI.getWIntType(), TI, Builder);
+  DefineTypeSizeAndWidth("__INTMAX", TI.getIntMaxType(), TI, Builder);
+  DefineTypeSizeAndWidth("__SIZE", TI.getSizeType(), TI, Builder);
 
-  DefineTypeSize("__UINTMAX_MAX__", TI.getUIntMaxType(), TI, Builder);
-  DefineTypeSize("__PTRDIFF_MAX__", TI.getPtrDiffType(0), TI, Builder);
-  DefineTypeSize("__INTPTR_MAX__", TI.getIntPtrType(), TI, Builder);
-  DefineTypeSize("__UINTPTR_MAX__", TI.getUIntPtrType(), TI, Builder);
+  DefineTypeSizeAndWidth("__UINTMAX", TI.getUIntMaxType(), TI, Builder);
+  DefineTypeSizeAndWidth("__PTRDIFF", TI.getPtrDiffType(0), TI, Builder);
+  DefineTypeSizeAndWidth("__INTPTR", TI.getIntPtrType(), TI, Builder);
+  DefineTypeSizeAndWidth("__UINTPTR", TI.getUIntPtrType(), TI, Builder);
 
   DefineTypeSizeof("__SIZEOF_DOUBLE__", TI.getDoubleWidth(), TI, Builder);
   DefineTypeSizeof("__SIZEOF_FLOAT__", TI.getFloatWidth(), TI, Builder);
@@ -929,29 +956,29 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
   DefineFmt("__UINTMAX", TI.getUIntMaxType(), TI, Builder);
   Builder.defineMacro("__UINTMAX_C_SUFFIX__",
                       TI.getTypeConstantSuffix(TI.getUIntMaxType()));
-  DefineTypeWidth("__INTMAX_WIDTH__",  TI.getIntMaxType(), TI, Builder);
   DefineType("__PTRDIFF_TYPE__", TI.getPtrDiffType(0), Builder);
   DefineFmt("__PTRDIFF", TI.getPtrDiffType(0), TI, Builder);
-  DefineTypeWidth("__PTRDIFF_WIDTH__", TI.getPtrDiffType(0), TI, Builder);
   DefineType("__INTPTR_TYPE__", TI.getIntPtrType(), Builder);
   DefineFmt("__INTPTR", TI.getIntPtrType(), TI, Builder);
-  DefineTypeWidth("__INTPTR_WIDTH__", TI.getIntPtrType(), TI, Builder);
   DefineType("__SIZE_TYPE__", TI.getSizeType(), Builder);
   DefineFmt("__SIZE", TI.getSizeType(), TI, Builder);
-  DefineTypeWidth("__SIZE_WIDTH__", TI.getSizeType(), TI, Builder);
   DefineType("__WCHAR_TYPE__", TI.getWCharType(), Builder);
-  DefineTypeWidth("__WCHAR_WIDTH__", TI.getWCharType(), TI, Builder);
   DefineType("__WINT_TYPE__", TI.getWIntType(), Builder);
-  DefineTypeWidth("__WINT_WIDTH__", TI.getWIntType(), TI, Builder);
-  DefineTypeWidth("__SIG_ATOMIC_WIDTH__", TI.getSigAtomicType(), TI, Builder);
-  DefineTypeSize("__SIG_ATOMIC_MAX__", TI.getSigAtomicType(), TI, Builder);
+  DefineTypeSizeAndWidth("__SIG_ATOMIC", TI.getSigAtomicType(), TI, Builder);
   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);
+
+  // The C standard requires the width of uintptr_t and intptr_t to be the same,
+  // per 7.20.2.4p1. Same for intmax_t and uintmax_t, per 7.20.2.5p1.
+  assert(TI.getTypeWidth(TI.getUIntPtrType()) ==
+             TI.getTypeWidth(TI.getIntPtrType()) &&
+         "uintptr_t and intptr_t have different widths?");
+  assert(TI.getTypeWidth(TI.getUIntMaxType()) ==
+             TI.getTypeWidth(TI.getIntMaxType()) &&
+         "uintmax_t and intmax_t have different widths?");
 
   if (TI.hasFloat16Type())
     DefineFloatMacros(Builder, "FLT16", &TI.getHalfFormat(), "F16");