[Clang] Allow 'Complex float __attribute__((mode(HC)))'

Adding half float to types that can be represented by __attribute__((mode(xx))).
Original implementation authored by George Steed.

Differential Revision: https://reviews.llvm.org/D126479

clang/docs/ReleaseNotes.rst

@@ -367,6 +367,8 @@ Attribute Changes in Clang
 - Added the ``clang::annotate_type`` attribute, which can be used to add
   annotations to types (see documentation for details).
 
+- Added half float to types that can be represented by ``__attribute__((mode(XX)))``.
+
 Windows Support
 ---------------
 

clang/include/clang/Basic/TargetInfo.h

@@ -53,11 +53,13 @@ namespace Builtin { struct Info; }
 
 enum class FloatModeKind {
   NoFloat = 255,
-  Float = 0,
+  Half = 0,
+  Float,
   Double,
   LongDouble,
   Float128,
-  Ibm128
+  Ibm128,
+  Last = Ibm128
 };
 
 /// Fields controlling how types are laid out in memory; these may need to
@@ -219,7 +221,7 @@ protected:
   mutable VersionTuple PlatformMinVersion;
 
   unsigned HasAlignMac68kSupport : 1;
-  unsigned RealTypeUsesObjCFPRet : 3;
+  unsigned RealTypeUsesObjCFPRetMask : (int)FloatModeKind::Last + 1;
   unsigned ComplexLongDoubleUsesFP2Ret : 1;
 
   unsigned HasBuiltinMSVaList : 1;
@@ -888,7 +890,9 @@ public:
   /// Check whether the given real type should use the "fpret" flavor of
   /// Objective-C message passing on this target.
   bool useObjCFPRetForRealType(FloatModeKind T) const {
-    return RealTypeUsesObjCFPRet & (1 << (int)T);
+    assert(T <= FloatModeKind::Last &&
+           "T value is larger than RealTypeUsesObjCFPRetMask can handle");
+    return RealTypeUsesObjCFPRetMask & (1 << (int)T);
   }
 
   /// Check whether _Complex long double should use the "fp2ret" flavor

clang/lib/AST/ASTContext.cpp

@@ -11758,6 +11758,8 @@ QualType ASTContext::getRealTypeForBitwidth(unsigned DestWidth,
   FloatModeKind Ty =
       getTargetInfo().getRealTypeByWidth(DestWidth, ExplicitType);
   switch (Ty) {
+  case FloatModeKind::Half:
+    return HalfTy;
   case FloatModeKind::Float:
     return FloatTy;
   case FloatModeKind::Double:

clang/lib/Basic/TargetInfo.cpp

@@ -131,7 +131,7 @@ TargetInfo::TargetInfo(const llvm::Triple &T) : Triple(T) {
   ARMCDECoprocMask = 0;
 
   // Default to no types using fpret.
-  RealTypeUsesObjCFPRet = 0;
+  RealTypeUsesObjCFPRetMask = 0;
 
   // Default to not using fp2ret for __Complex long double
   ComplexLongDoubleUsesFP2Ret = false;
@@ -287,6 +287,8 @@ TargetInfo::IntType TargetInfo::getLeastIntTypeByWidth(unsigned BitWidth,
 
 FloatModeKind TargetInfo::getRealTypeByWidth(unsigned BitWidth,
                                              FloatModeKind ExplicitType) const {
+  if (getHalfWidth() == BitWidth)
+    return FloatModeKind::Half;
   if (getFloatWidth() == BitWidth)
     return FloatModeKind::Float;
   if (getDoubleWidth() == BitWidth)

clang/lib/Basic/Targets/X86.h

@@ -418,7 +418,7 @@ public:
     RegParmMax = 3;
 
     // Use fpret for all types.
-    RealTypeUsesObjCFPRet =
+    RealTypeUsesObjCFPRetMask =
         ((1 << (int)FloatModeKind::Float) | (1 << (int)FloatModeKind::Double) |
          (1 << (int)FloatModeKind::LongDouble));
 
@@ -699,7 +699,7 @@ public:
                                         "64-i64:64-f80:128-n8:16:32:64-S128");
 
     // Use fpret only for long double.
-    RealTypeUsesObjCFPRet = (1 << (int)FloatModeKind::LongDouble);
+    RealTypeUsesObjCFPRetMask = (1 << (int)FloatModeKind::LongDouble);
 
     // Use fp2ret for _Complex long double.
     ComplexLongDoubleUsesFP2Ret = true;

clang/test/CodeGen/aarch64-attr-mode-complex.c

@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -triple arm64-none-linux-gnu -emit-llvm %s -o - | FileCheck %s
+
+typedef _Complex float c16a __attribute((mode(HC)));
+typedef _Complex double c16b __attribute((mode(HC)));
+typedef _Complex float c32a __attribute((mode(SC)));
+typedef _Complex double c32b __attribute((mode(SC)));
+typedef _Complex float c64a __attribute((mode(DC)));
+typedef _Complex double c64b __attribute((mode(DC)));
+
+// CHECK: define{{.*}} { half, half } @c16_test([2 x half] noundef {{.*}}
+// CHECK:   ret { half, half } {{.*}}
+c16b c16_test(c16a x) {
+  return x + x;
+}
+
+// CHECK: define{{.*}} { float, float } @c32_test([2 x float] noundef {{.*}})
+// CHECK:   ret { float, float } {{.*}}
+c32b c32_test(c32a x) {
+  return x + x;
+}
+
+// CHECK: define{{.*}} { double, double } @c64_test([2 x double] noundef {{.*}})
+// CHECK:   ret { double, double } {{.*}}
+c64b c64_test(c64a x) {
+  return x + x;
+}

clang/test/CodeGen/aarch64-attr-mode-float.c

@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 -triple arm64-none-linux-gnu -emit-llvm %s -o - | FileCheck %s
+
+typedef float f16a __attribute((mode(HF)));
+typedef double f16b __attribute((mode(HF)));
+typedef float f32a __attribute((mode(SF)));
+typedef double f32b __attribute((mode(SF)));
+typedef float f64a __attribute((mode(DF)));
+typedef double f64b __attribute((mode(DF)));
+f16b tmp;
+
+// CHECK: define{{.*}} ptr @f16_test(ptr noundef {{.*}})
+// CHECK:   store half {{.*}}, ptr @tmp, align 2
+// CHECK:   ret ptr @tmp
+f16b *f16_test(f16a *x) {
+  tmp = *x + *x;
+  return &tmp;
+}
+
+// CHECK: define{{.*}} float @f32_test(float noundef {{.*}})
+// CHECK:   ret float {{.*}}
+f32b f32_test(f32a x) {
+  return x + x;
+}
+
+// CHECK: define{{.*}} double @f64_test(double noundef {{.*}})
+// CHECK:   ret double {{.*}}
+f64b f64_test(f64a x) {
+  return x + x;
+}

clang/test/Sema/attr-mode-vector-types.c

@@ -22,8 +22,7 @@ typedef float __attribute__((mode(QC))) __attribute__((vector_size(256))) vec_t8
 // expected-error@-1{{unsupported machine mode 'QC'}}
 // expected-error@-2{{type of machine mode does not match type of base type}}
 typedef _Complex float __attribute__((mode(HC))) __attribute__((vector_size(256))) vec_t9;
-// expected-error@-1{{unsupported machine mode 'HC'}}
-// expected-error@-2{{invalid vector element type '_Complex float'}}
+// expected-error@-1{{invalid vector element type '_Complex float'}}
 typedef int __attribute__((mode(SC))) __attribute__((vector_size(256))) vec_t10;
 // expected-error@-1{{type of machine mode does not match type of base type}}
 // expected-error@-2{{type of machine mode does not support base vector types}}

clang/test/Sema/attr-mode.c

@@ -37,6 +37,11 @@ int **__attribute((mode(QI)))* i32;  // expected-error{{mode attribute}}
 __attribute__((mode(QI))) int invalid_func(void) { return 1; } // expected-error{{'mode' attribute only applies to variables, enums, typedefs, and non-static data members}}
 enum invalid_enum { A1 __attribute__((mode(QI))) }; // expected-error{{'mode' attribute only applies to}}
 
+typedef _Complex float c16a __attribute((mode(HC)));
+int c16a_test[sizeof(c16a) == 4 ? 1 : -1];
+typedef _Complex double c16b __attribute((mode(HC)));
+int c16b_test[sizeof(c16b) == 4 ? 1 : -1];
+
 typedef _Complex double c32 __attribute((mode(SC)));
 int c32_test[sizeof(c32) == 8 ? 1 : -1];
 typedef _Complex float c64 __attribute((mode(DC)));