[Clang] Add __builtin_bswapg

clang/docs/ReleaseNotes.rst

@@ -270,6 +270,9 @@ Non-comprehensive list of changes in this release
   allocator-level heap organization strategies. A feature to instrument all
   allocation functions with a token ID can be enabled via the
   ``-fsanitize=alloc-token`` flag.
+
+- A new generic byte swap builtin function ``__builtin_bswapg`` that extends the existing 
+  __builtin_bswap{16,32,64} function family to support all standard integer types.
 
 New Compiler Flags
 ------------------

clang/include/clang/Basic/Builtins.td

@@ -755,6 +755,12 @@ def BSwap : Builtin, Template<["unsigned short", "uint32_t", "uint64_t"],
   let Prototype = "T(T)";
 }
 
+def BSwapg : Builtin {
+  let Spellings = ["__builtin_bswapg"];
+  let Attributes = [NoThrow, Const, Constexpr, CustomTypeChecking];
+  let Prototype = "int(...)";
+}
+
 def Bitreverse : BitInt8_16_32_64BuiltinsTemplate, Builtin {
   let Spellings = ["__builtin_bitreverse"];
   let Attributes = [NoThrow, Const, Constexpr];

clang/lib/AST/ByteCode/InterpBuiltin.cpp

@@ -970,8 +970,10 @@ static bool interp__builtin_bswap(InterpState &S, CodePtr OpPC,
                                   const CallExpr *Call) {
   const APSInt &Val = popToAPSInt(S, Call->getArg(0));
   assert(Val.getActiveBits() <= 64);
-
-  pushInteger(S, Val.byteSwap(), Call->getType());
+  if (Val.getBitWidth() == 8)
+    pushInteger(S, Val, Call->getType());
+  else
+    pushInteger(S, Val.byteSwap(), Call->getType());
   return true;
 }
 
@@ -3370,7 +3372,7 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const CallExpr *Call,
   case Builtin::BI__builtin_elementwise_ctzg:
     return interp__builtin_elementwise_countzeroes(S, OpPC, Frame, Call,
                                                    BuiltinID);
-
+  case Builtin::BI__builtin_bswapg:
   case Builtin::BI__builtin_bswap16:
   case Builtin::BI__builtin_bswap32:
   case Builtin::BI__builtin_bswap64:

clang/lib/AST/ExprConstant.cpp

@@ -14279,13 +14279,15 @@ bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
 
     return Success(Val.reverseBits(), E);
   }
-
+  case Builtin::BI__builtin_bswapg:
   case Builtin::BI__builtin_bswap16:
   case Builtin::BI__builtin_bswap32:
   case Builtin::BI__builtin_bswap64: {
     APSInt Val;
     if (!EvaluateInteger(E->getArg(0), Val, Info))
       return false;
+    if (Val.getBitWidth() == 8)
+      return Success(Val, E);
 
     return Success(Val.byteSwap(), E);
   }

clang/lib/CodeGen/CGBuiltin.cpp

@@ -3622,6 +3622,17 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
           Builder.CreateArithmeticFence(ArgValue, ConvertType(ArgType)));
     return RValue::get(ArgValue);
   }
+  case Builtin::BI__builtin_bswapg: {
+    Value *ArgValue = EmitScalarExpr(E->getArg(0));
+    llvm::IntegerType *IntTy = cast<llvm::IntegerType>(ArgValue->getType());
+    assert(IntTy && "LLVM's __builtin_bswapg only supports integer variants");
+    assert(((IntTy->getBitWidth() % 16 == 0 && IntTy->getBitWidth() != 0) || IntTy->getBitWidth() == 8) && 
+        "LLVM's __builtin_bswapg only supports integer variants that has a multiple of 16 bits as well as a single byte");
+    if (IntTy->getBitWidth() == 8)
+      return RValue::get(ArgValue);
+    return RValue::get(
+        emitBuiltinWithOneOverloadedType<1>(*this, E, Intrinsic::bswap));
+  }
   case Builtin::BI__builtin_bswap16:
   case Builtin::BI__builtin_bswap32:
   case Builtin::BI__builtin_bswap64:

clang/lib/Sema/SemaChecking.cpp

@@ -2200,6 +2200,32 @@ static bool BuiltinCpu(Sema &S, const TargetInfo &TI, CallExpr *TheCall,
   return false;
 }
 
+/// Checks that __builtin_bswapg was called with a single argument, which is an
+/// unsigned integer, and overrides the return value type to the integer type.
+static bool BuiltinBswapg(Sema &S, CallExpr *TheCall) {
+  if (S.checkArgCount(TheCall, 1))
+    return true;
+  ExprResult ArgRes = S.DefaultLvalueConversion(TheCall->getArg(0));
+  if (ArgRes.isInvalid())
+    return true;
+
+  Expr *Arg = ArgRes.get();
+  TheCall->setArg(0, Arg);
+  if (Arg->isTypeDependent())
+    return false;
+
+  QualType ArgTy = Arg->getType();
+
+  if (!ArgTy->isIntegerType()) {
+    S.Diag(Arg->getBeginLoc(), diag::err_builtin_invalid_arg_type)
+        << 1 << /*scalar=*/ 1 << /*unsigned integer=*/ 1 << /*floating point=*/ 0
+        << ArgTy;
+    return true;
+  }
+  TheCall->setType(ArgTy);
+  return false;
+}
+
 /// Checks that __builtin_popcountg was called with a single argument, which is
 /// an unsigned integer.
 static bool BuiltinPopcountg(Sema &S, CallExpr *TheCall) {
@@ -3448,6 +3474,10 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
     }
     break;
   }
+  case Builtin::BI__builtin_bswapg:
+    if (BuiltinBswapg(*this, TheCall))
+      return ExprError();
+    break;
   case Builtin::BI__builtin_popcountg:
     if (BuiltinPopcountg(*this, TheCall))
       return ExprError();

clang/test/AST/ByteCode/builtin-functions.cpp

@@ -824,6 +824,29 @@ namespace bswap {
   int h3 = __builtin_bswap16(0x1234) == 0x3412 ? 1 : f();
   int h4 = __builtin_bswap32(0x1234) == 0x34120000 ? 1 : f();
   int h5 = __builtin_bswap64(0x1234) == 0x3412000000000000 ? 1 : f();
+  int h6 = __builtin_bswapg(0x12) == 0x12 ? 1 : f();
+  int h7 = __builtin_bswapg(0x1234) == 0x3412 ? 1 : f();
+  int h8 = __builtin_bswapg(0x00001234) == 0x34120000 ? 1 : f();
+  int h9 = __builtin_bswapg(0x0000000000001234) == 0x3412000000000000 ? 1 : f();
+
+  constexpr const int const_expr = 0x1234;
+
+  void test_constexpr_reference() {
+    const int expr = 0x1234; 
+    const int& ref = expr; // #declare
+
+    constexpr const int& const_ref = const_expr;
+
+    constexpr auto result2 = __builtin_bswapg(ref); 
+    //expected-error@-1 {{constexpr variable 'result2' must be initialized by a constant expression}}
+    //expected-note@-2 {{initializer of 'ref' is not a constant expression}}
+    //expected-note@#declare {{declared here}}
+    //ref-error@-4 {{constexpr variable 'result2' must be initialized by a constant expression}}
+    //ref-note@-5 {{initializer of 'ref' is not a constant expression}}
+    //ref-note@#declare {{declared here}}
+
+    constexpr auto result3 = __builtin_bswapg(const_ref);
+  }
 }
 
 #define CFSTR __builtin___CFStringMakeConstantString

clang/test/CodeGen/builtins.c

@@ -130,7 +130,10 @@ int main(void) {
   P(object_size, (s0, 3));
 
   // Whatever
-
+  P(bswapg, ((char)N));
+  P(bswapg, ((short)N));
+  P(bswapg, ((int)N));
+  P(bswapg, ((unsigned long)N));
   P(bswap16, (N));
   P(bswap32, (N));
   P(bswap64, (N));

clang/test/CodeGenCXX/builtins.cpp

@@ -83,3 +83,40 @@ int structured_binding_size() {
   return __builtin_structured_binding_size(S2);
   // CHECK: ret i32 2
 }
+
+void test_int_reference(int& a) {
+    __builtin_bswapg(a);
+}
+// CHECK-LABEL: @_Z18test_int_referenceRi
+// CHECK: store ptr %a, ptr
+// CHECK: load ptr, ptr
+// CHECK: load i32, ptr
+// CHECK: call i32 @llvm.bswap.i32
+
+void test_long_reference(long& a) {
+    __builtin_bswapg(a);
+}
+// CHECK-LABEL: @_Z19test_long_referenceRl
+// CHECK: store ptr %a, ptr
+// CHECK: load ptr, ptr
+// CHECK: load i64, ptr
+// CHECK: call i64 @llvm.bswap.i64
+
+// 2. 不同大小的引用测试
+void test_short_reference(short& a) {
+    __builtin_bswapg(a);
+}
+// CHECK-LABEL: @_Z20test_short_referenceRs
+// CHECK: store ptr %a, ptr
+// CHECK: load ptr, ptr 
+// CHECK: load i16, ptr
+// CHECK: call i16 @llvm.bswap.i16
+
+void test_char_reference(char& a) {
+    __builtin_bswapg(a);
+}
+// CHECK-LABEL: @_Z19test_char_referenceRc
+// CHECK: store ptr %a, ptr
+// CHECK: load ptr, ptr
+// CHECK-NOT: call i8 @llvm.bswap.i8
+// CHECK: ret void

clang/test/Sema/constant-builtins-2.c

@@ -479,6 +479,21 @@ int h0 = __builtin_types_compatible_p(int, float);
 int h3 = __builtin_bswap16(0x1234) == 0x3412 ? 1 : f();
 int h4 = __builtin_bswap32(0x1234) == 0x34120000 ? 1 : f();
 int h5 = __builtin_bswap64(0x1234) == 0x3412000000000000 ? 1 : f();
+int h6 = __builtin_bswapg((char)(0x12)) == (char)(0x12) ? 1 : f();
+int h7 = __builtin_bswapg((short)(0x1234)) == (short)(0x3412) ? 1 : f();
+int h8 = __builtin_bswapg(0x00001234) == 0x34120000 ? 1 : f();
+int h9 = __builtin_bswapg(0x0000000000001234ULL) == 0x3412000000000000 ? 1 : f();
+float h10 = __builtin_bswapg(1.0f); // expected-error {{1st argument must be a scalar integer type (was 'float')}}
+double h12 = __builtin_bswapg(1.0L); // expected-error {{1st argument must be a scalar integer type (was 'long double')}}
+char *h13 = __builtin_bswapg("hello"); // expected-error {{1st argument must be a scalar integer type (was 'char[6]')}}
+int h14 = __builtin_bswapg(1, 2); // expected-error {{too many arguments to function call, expected 1, have 2}}
+int *h15 = __builtin_bswapg(&h9); // expected-error {{1st argument must be a scalar integer type (was 'int *')}}
+int arr[4] = {0x12, 0x34, 0x56, 0x78};
+int h16 = __builtin_bswapg(arr); // expected-error {{1st argument must be a scalar integer type (was 'int[4]')}}
+enum BasicEnum {
+  ENUM_VALUE1 = 0x1234,
+};
+int h17 = __builtin_bswapg(ENUM_VALUE1) == 0x34120000 ? 1 : f();
 extern long int bi0;
 extern __typeof__(__builtin_expect(0, 0)) bi0;
 

clang/test/Sema/constant-builtins.c

@@ -25,7 +25,10 @@ int h0 = __builtin_types_compatible_p(int,float);
 int h3 = __builtin_bswap16(0x1234) == 0x3412 ? 1 : f();
 int h4 = __builtin_bswap32(0x1234) == 0x34120000 ? 1 : f();
 int h5 = __builtin_bswap64(0x1234) == 0x3412000000000000 ? 1 : f();
-
+int h6 = __builtin_bswapg((char)0x12) == (char)0x12 ? 1 : f();
+int h7 = __builtin_bswapg((short)(0x1234)) == (short)(0x3412) ? 1 : f();
+int h8 = __builtin_bswapg(0x00001234) == 0x34120000 ? 1 : f();
+int h9 = __builtin_bswapg(0x0000000000001234ULL) == 0x3412000000000000 ? 1 : f();
 short somefunc(void);
 
 short t = __builtin_constant_p(5353) ? 42 : somefunc();