[Clang] Enable KF and KC mode for [_Complex] __float128

The headers provided with recent GNU toolchains for PPC have code that includes
typedefs such as:

typedef _Complex float __cfloat128 __attribute__ ((__mode__ (__KC__)))

This patch allows clang to compile programs that contain
#include <math.h>

with -mfloat128 which it currently fails to compile.

Fixes: https://bugs.llvm.org/show_bug.cgi?id=46068

Differential revision: https://reviews.llvm.org/D80374

Author: nemanjai

clang/include/clang/AST/ASTContext.h

@@ -657,7 +657,7 @@ class ASTContext : public RefCountedBase<ASTContext> {
   /// getRealTypeForBitwidth -
   /// sets floating point QualTy according to specified bitwidth.
   /// Returns empty type if there is no appropriate target types.
-  QualType getRealTypeForBitwidth(unsigned DestWidth) const;
+  QualType getRealTypeForBitwidth(unsigned DestWidth, bool ExplicitIEEE) const;
 
   bool AtomicUsesUnsupportedLibcall(const AtomicExpr *E) const;
 

clang/include/clang/Basic/TargetInfo.h

@@ -368,8 +368,13 @@ class TargetInfo : public virtual TransferrableTargetInfo,
   virtual IntType getLeastIntTypeByWidth(unsigned BitWidth,
                                          bool IsSigned) const;
 
-  /// Return floating point type with specified width.
-  RealType getRealTypeByWidth(unsigned BitWidth) const;
+  /// Return floating point type with specified width. On PPC, there are
+  /// three possible types for 128-bit floating point: "PPC double-double",
+  /// IEEE 754R quad precision, and "long double" (which under the covers
+  /// is represented as one of those two). At this time, there is no support
+  /// for an explicit "PPC double-double" type (i.e. __ibm128) so we only
+  /// need to differentiate between "long double" and IEEE quad precision.
+  RealType getRealTypeByWidth(unsigned BitWidth, bool ExplicitIEEE) const;
 
   /// Return the alignment (in bits) of the specified integer type enum.
   ///

clang/lib/AST/ASTContext.cpp

@@ -10644,8 +10644,10 @@ QualType ASTContext::getIntTypeForBitwidth(unsigned DestWidth,
 /// getRealTypeForBitwidth -
 /// sets floating point QualTy according to specified bitwidth.
 /// Returns empty type if there is no appropriate target types.
-QualType ASTContext::getRealTypeForBitwidth(unsigned DestWidth) const {
-  TargetInfo::RealType Ty = getTargetInfo().getRealTypeByWidth(DestWidth);
+QualType ASTContext::getRealTypeForBitwidth(unsigned DestWidth,
+                                            bool ExplicitIEEE) const {
+  TargetInfo::RealType Ty =
+      getTargetInfo().getRealTypeByWidth(DestWidth, ExplicitIEEE);
   switch (Ty) {
   case TargetInfo::Float:
     return FloatTy;

clang/lib/Basic/TargetInfo.cpp

@@ -265,7 +265,8 @@ TargetInfo::IntType TargetInfo::getLeastIntTypeByWidth(unsigned BitWidth,
   return NoInt;
 }
 
-TargetInfo::RealType TargetInfo::getRealTypeByWidth(unsigned BitWidth) const {
+TargetInfo::RealType TargetInfo::getRealTypeByWidth(unsigned BitWidth,
+                                                    bool ExplicitIEEE) const {
   if (getFloatWidth() == BitWidth)
     return Float;
   if (getDoubleWidth() == BitWidth)
@@ -277,6 +278,10 @@ TargetInfo::RealType TargetInfo::getRealTypeByWidth(unsigned BitWidth) const {
       return LongDouble;
     break;
   case 128:
+    // The caller explicitly asked for an IEEE compliant type but we still
+    // have to check if the target supports it.
+    if (ExplicitIEEE)
+      return hasFloat128Type() ? Float128 : NoFloat;
     if (&getLongDoubleFormat() == &llvm::APFloat::PPCDoubleDouble() ||
         &getLongDoubleFormat() == &llvm::APFloat::IEEEquad())
       return LongDouble;

clang/lib/Sema/SemaDeclAttr.cpp

@@ -3942,7 +3942,8 @@ bool Sema::checkMSInheritanceAttrOnDefinition(
 /// parseModeAttrArg - Parses attribute mode string and returns parsed type
 /// attribute.
 static void parseModeAttrArg(Sema &S, StringRef Str, unsigned &DestWidth,
-                             bool &IntegerMode, bool &ComplexMode) {
+                             bool &IntegerMode, bool &ComplexMode,
+                             bool &ExplicitIEEE) {
   IntegerMode = true;
   ComplexMode = false;
   switch (Str.size()) {
@@ -3963,7 +3964,12 @@ static void parseModeAttrArg(Sema &S, StringRef Str, unsigned &DestWidth,
     case 'X':
       DestWidth = 96;
       break;
+    case 'K': // KFmode - IEEE quad precision (__float128)
+      ExplicitIEEE = true;
+      DestWidth = Str[1] == 'I' ? 0 : 128;
+      break;
     case 'T':
+      ExplicitIEEE = false;
       DestWidth = 128;
       break;
     }
@@ -4024,6 +4030,7 @@ void Sema::AddModeAttr(Decl *D, const AttributeCommonInfo &CI,
   unsigned DestWidth = 0;
   bool IntegerMode = true;
   bool ComplexMode = false;
+  bool ExplicitIEEE = false;
   llvm::APInt VectorSize(64, 0);
   if (Str.size() >= 4 && Str[0] == 'V') {
     // Minimal length of vector mode is 4: 'V' + NUMBER(>=1) + TYPE(>=2).
@@ -4036,7 +4043,7 @@ void Sema::AddModeAttr(Decl *D, const AttributeCommonInfo &CI,
         !Str.substr(1, VectorStringLength).getAsInteger(10, VectorSize) &&
         VectorSize.isPowerOf2()) {
       parseModeAttrArg(*this, Str.substr(VectorStringLength + 1), DestWidth,
-                       IntegerMode, ComplexMode);
+                       IntegerMode, ComplexMode, ExplicitIEEE);
       // Avoid duplicate warning from template instantiation.
       if (!InInstantiation)
         Diag(AttrLoc, diag::warn_vector_mode_deprecated);
@@ -4046,7 +4053,8 @@ void Sema::AddModeAttr(Decl *D, const AttributeCommonInfo &CI,
   }
 
   if (!VectorSize)
-    parseModeAttrArg(*this, Str, DestWidth, IntegerMode, ComplexMode);
+    parseModeAttrArg(*this, Str, DestWidth, IntegerMode, ComplexMode,
+                     ExplicitIEEE);
 
   // FIXME: Sync this with InitializePredefinedMacros; we need to match int8_t
   // and friends, at least with glibc.
@@ -4112,7 +4120,7 @@ void Sema::AddModeAttr(Decl *D, const AttributeCommonInfo &CI,
     NewElemTy = Context.getIntTypeForBitwidth(DestWidth,
                                               OldElemTy->isSignedIntegerType());
   else
-    NewElemTy = Context.getRealTypeForBitwidth(DestWidth);
+    NewElemTy = Context.getRealTypeForBitwidth(DestWidth, ExplicitIEEE);
 
   if (NewElemTy.isNull()) {
     Diag(AttrLoc, diag::err_machine_mode) << 1 /*Unsupported*/ << Name;

clang/test/Sema/attr-mode.c

@@ -4,6 +4,8 @@
 // RUN:   -verify %s
 // RUN: %clang_cc1 -triple powerpc64-pc-linux-gnu -DTEST_64BIT_PPC64 -fsyntax-only \
 // RUN:   -verify %s
+// RUN: %clang_cc1 -triple powerpc64-pc-linux-gnu -DTEST_F128_PPC64 -fsyntax-only \
+// RUN:   -verify -target-feature +float128 %s
 // RUN: %clang_cc1 -triple x86_64-pc-linux-gnux32 -DTEST_64BIT_X86 -fsyntax-only \
 // RUN:   -verify %s
 // RUN: %clang_cc1 -triple mips-linux-gnu -DTEST_MIPS_32 -fsyntax-only \
@@ -90,6 +92,15 @@ void f_ft128_arg(long double *x);
 void f_ft128_complex_arg(_Complex long double *x);
 void test_TFtype(f128ibm *a) { f_ft128_arg (a); }
 void test_TCtype(c128ibm *a) { f_ft128_complex_arg (a); }
+#elif TEST_F128_PPC64
+typedef int invalid_7 __attribute((mode(KF))); // expected-error{{type of machine mode does not match type of base type}}
+typedef int invalid_8 __attribute((mode(KI))); // expected-error{{unknown machine mode}}
+typedef _Complex float cf128 __attribute__((mode(KC)));
+typedef float f128 __attribute__((mode(KF)));
+void f_f128_arg(__float128 *x);
+void f_f128_complex_arg(_Complex __float128 *x);
+void test_KFtype(f128 *a) { f_f128_arg(a); }
+void test_KCtype(cf128 *a) { f_f128_complex_arg(a); }
 #elif TEST_MIPS_32
 typedef unsigned int gcc_unwind_word __attribute__((mode(unwind_word)));
 int foo[sizeof(gcc_unwind_word) == 4 ? 1 : -1];