[clang] constexpr integer __builtin_elementwise_{max,min}

clang/docs/LanguageExtensions.rst

@@ -759,7 +759,8 @@ Unless specified otherwise operation(±0) = ±0 and operation(±infinity) = ±in
 
 The integer elementwise intrinsics, including ``__builtin_elementwise_popcount``,
 ``__builtin_elementwise_bitreverse``, ``__builtin_elementwise_add_sat``,
-``__builtin_elementwise_sub_sat`` can be called in a ``constexpr`` context.
+``__builtin_elementwise_sub_sat``, ``__builtin_elementwise_max``,
+``__builtin_elementwise_min`` can be called in a ``constexpr`` context.
 
 No implicit promotion of integer types takes place. The mixing of integer types
 of different sizes and signs is forbidden in binary and ternary builtins.

clang/docs/ReleaseNotes.rst

@@ -120,6 +120,9 @@ Non-comprehensive list of changes in this release
   This feature is enabled by default but can be disabled by compiling with 
   ``-fno-sanitize-annotate-debug-info-traps``.
 
+- ``__builtin_elementwise_max`` and ``__builtin_elementwise_min`` functions for integer types can
+  now be used in constant expressions.
+
 New Compiler Flags
 ------------------
 - New option ``-fno-sanitize-annotate-debug-info-traps`` added to disable emitting trap reasons into the debug info when compiling with trapping UBSan (e.g. ``-fsanitize-trap=undefined``).

clang/include/clang/Basic/Builtins.td

@@ -1300,13 +1300,13 @@ def ElementwiseBitreverse : Builtin {
 
 def ElementwiseMax : Builtin {
   let Spellings = ["__builtin_elementwise_max"];
-  let Attributes = [NoThrow, Const, CustomTypeChecking];
+  let Attributes = [NoThrow, Const, CustomTypeChecking, Constexpr];
   let Prototype = "void(...)";
 }
 
 def ElementwiseMin : Builtin {
   let Spellings = ["__builtin_elementwise_min"];
-  let Attributes = [NoThrow, Const, CustomTypeChecking];
+  let Attributes = [NoThrow, Const, CustomTypeChecking, Constexpr];
   let Prototype = "void(...)";
 }
 

clang/lib/AST/ByteCode/InterpBuiltin.cpp

@@ -2253,7 +2253,6 @@ static bool interp__builtin_is_within_lifetime(InterpState &S, CodePtr OpPC,
 static bool interp__builtin_elementwise_sat(InterpState &S, CodePtr OpPC,
                                             const CallExpr *Call,
                                             unsigned BuiltinID) {
-  Call->dumpColor();
   assert(Call->getNumArgs() == 2);
 
   // Single integer case.
@@ -2320,6 +2319,80 @@ static bool interp__builtin_elementwise_sat(InterpState &S, CodePtr OpPC,
   return true;
 }
 
+static bool interp__builtin_elementwise_maxmin(InterpState &S, CodePtr OpPC,
+                                               const CallExpr *Call,
+                                               unsigned BuiltinID) {
+  assert(Call->getNumArgs() == 2);
+
+  QualType Arg0Type = Call->getArg(0)->getType();
+
+  // TODO: Support floating-point types.
+  if (!(Arg0Type->isIntegerType() ||
+        (Arg0Type->isVectorType() &&
+         Arg0Type->castAs<VectorType>()->getElementType()->isIntegerType())))
+    return false;
+
+  if (!Arg0Type->isVectorType()) {
+    assert(!Call->getArg(1)->getType()->isVectorType());
+    APSInt RHS = popToAPSInt(
+        S.Stk, *S.getContext().classify(Call->getArg(1)->getType()));
+    APSInt LHS = popToAPSInt(
+        S.Stk, *S.getContext().classify(Call->getArg(0)->getType()));
+    APInt Result;
+    if (BuiltinID == Builtin::BI__builtin_elementwise_max) {
+      Result = std::max(LHS, RHS);
+    } else if (BuiltinID == Builtin::BI__builtin_elementwise_min) {
+      Result = std::min(LHS, RHS);
+    } else {
+      llvm_unreachable("Wrong builtin ID");
+    }
+
+    pushInteger(S, APSInt(Result, !LHS.isSigned()), Call->getType());
+    return true;
+  }
+
+  // Vector case.
+  assert(Call->getArg(0)->getType()->isVectorType() &&
+         Call->getArg(1)->getType()->isVectorType());
+  const auto *VT = Call->getArg(0)->getType()->castAs<VectorType>();
+  assert(VT->getElementType() ==
+         Call->getArg(1)->getType()->castAs<VectorType>()->getElementType());
+  assert(VT->getNumElements() ==
+         Call->getArg(1)->getType()->castAs<VectorType>()->getNumElements());
+  assert(VT->getElementType()->isIntegralOrEnumerationType());
+
+  const Pointer &RHS = S.Stk.pop<Pointer>();
+  const Pointer &LHS = S.Stk.pop<Pointer>();
+  const Pointer &Dst = S.Stk.peek<Pointer>();
+  PrimType ElemT = *S.getContext().classify(VT->getElementType());
+  unsigned NumElems = VT->getNumElements();
+  for (unsigned I = 0; I != NumElems; ++I) {
+    APSInt Elem1;
+    APSInt Elem2;
+    INT_TYPE_SWITCH_NO_BOOL(ElemT, {
+      Elem1 = LHS.elem<T>(I).toAPSInt();
+      Elem2 = RHS.elem<T>(I).toAPSInt();
+    });
+
+    APSInt Result;
+    if (BuiltinID == Builtin::BI__builtin_elementwise_max) {
+      Result = APSInt(std::max(Elem1, Elem2),
+                      Call->getType()->isUnsignedIntegerOrEnumerationType());
+    } else if (BuiltinID == Builtin::BI__builtin_elementwise_min) {
+      Result = APSInt(std::min(Elem1, Elem2),
+                      Call->getType()->isUnsignedIntegerOrEnumerationType());
+    } else {
+      llvm_unreachable("Wrong builtin ID");
+    }
+
+    INT_TYPE_SWITCH_NO_BOOL(ElemT,
+                            { Dst.elem<T>(I) = static_cast<T>(Result); });
+  }
+  Dst.initializeAllElements();
+
+  return true;
+}
+
 bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const CallExpr *Call,
                       uint32_t BuiltinID) {
   if (!S.getASTContext().BuiltinInfo.isConstantEvaluated(BuiltinID))
@@ -2727,6 +2800,10 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const CallExpr *Call,
   case Builtin::BI__builtin_elementwise_sub_sat:
     return interp__builtin_elementwise_sat(S, OpPC, Call, BuiltinID);
 
+  case Builtin::BI__builtin_elementwise_max:
+  case Builtin::BI__builtin_elementwise_min:
+    return interp__builtin_elementwise_maxmin(S, OpPC, Call, BuiltinID);
+
   default:
     S.FFDiag(S.Current->getLocation(OpPC),
              diag::note_invalid_subexpr_in_const_expr)

clang/lib/AST/ExprConstant.cpp

@@ -11654,6 +11654,41 @@ bool VectorExprEvaluator::VisitCallExpr(const CallExpr *E) {
 
     return Success(APValue(ResultElements.data(), ResultElements.size()), E);
   }
+  case Builtin::BI__builtin_elementwise_max:
+  case Builtin::BI__builtin_elementwise_min: {
+    APValue SourceLHS, SourceRHS;
+    if (!EvaluateAsRValue(Info, E->getArg(0), SourceLHS) ||
+        !EvaluateAsRValue(Info, E->getArg(1), SourceRHS))
+      return false;
+
+    QualType DestEltTy = E->getType()->castAs<VectorType>()->getElementType();
+
+    if (!DestEltTy->isIntegerType())
+      return false;
+
+    unsigned SourceLen = SourceLHS.getVectorLength();
+    SmallVector<APValue, 4> ResultElements;
+    ResultElements.reserve(SourceLen);
+
+    for (unsigned EltNum = 0; EltNum < SourceLen; ++EltNum) {
+      APSInt LHS = SourceLHS.getVectorElt(EltNum).getInt();
+      APSInt RHS = SourceRHS.getVectorElt(EltNum).getInt();
+      switch (E->getBuiltinCallee()) {
+      case Builtin::BI__builtin_elementwise_max:
+        ResultElements.push_back(
+            APValue(APSInt(std::max(LHS, RHS),
+                           DestEltTy->isUnsignedIntegerOrEnumerationType())));
+        break;
+      case Builtin::BI__builtin_elementwise_min:
+        ResultElements.push_back(
+            APValue(APSInt(std::min(LHS, RHS),
+                           DestEltTy->isUnsignedIntegerOrEnumerationType())));
+        break;
+      }
+    }
+
+    return Success(APValue(ResultElements.data(), ResultElements.size()), E);
+  }
   }
 }
 
@@ -13548,7 +13583,24 @@ bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
     APInt Result = LHS.isSigned() ? LHS.ssub_sat(RHS) : LHS.usub_sat(RHS);
     return Success(APSInt(Result, !LHS.isSigned()), E);
   }
+  case Builtin::BI__builtin_elementwise_max: {
+    APSInt LHS, RHS;
+    if (!EvaluateInteger(E->getArg(0), LHS, Info) ||
+        !EvaluateInteger(E->getArg(1), RHS, Info))
+      return false;
+
+    APInt Result = std::max(LHS, RHS);
+    return Success(APSInt(Result, !LHS.isSigned()), E);
+  }
+  case Builtin::BI__builtin_elementwise_min: {
+    APSInt LHS, RHS;
+    if (!EvaluateInteger(E->getArg(0), LHS, Info) ||
+        !EvaluateInteger(E->getArg(1), RHS, Info))
+      return false;
 
+    APInt Result = std::min(LHS, RHS);
+    return Success(APSInt(Result, !LHS.isSigned()), E);
+  }
   case Builtin::BIstrlen:
   case Builtin::BIwcslen:
     // A call to strlen is not a constant expression.

clang/test/CodeGen/builtins-elementwise-math.c

@@ -418,7 +418,7 @@ void test_builtin_elementwise_max(float f1, float f2, double d1, double d2,
   // CHECK-NEXT: call i32 @llvm.smax.i32(i32 [[IAS1]], i32 [[B]])
   int_as_one = __builtin_elementwise_max(int_as_one, b);
 
-  // CHECK: call i32 @llvm.smax.i32(i32 1, i32 97)
+  // CHECK: store i64 97, ptr [[I1:%.+]], align 8
   i1 = __builtin_elementwise_max(1, 'a');
 }
 
@@ -508,6 +508,9 @@ void test_builtin_elementwise_min(float f1, float f2, double d1, double d2,
   // CHECK-NEXT: [[B:%.+]] = load i32, ptr @b, align 4
   // CHECK-NEXT: call i32 @llvm.smin.i32(i32 [[IAS1]], i32 [[B]])
   int_as_one = __builtin_elementwise_min(int_as_one, b);
+
+  // CHECK: store i64 2, ptr [[I1:%.+]], align 8
+  i1 = __builtin_elementwise_min(2, 'b');
 }
 
 void test_builtin_elementwise_bitreverse(si8 vi1, si8 vi2,

clang/test/Sema/constant-builtins-vector.cpp

@@ -860,3 +860,19 @@ static_assert(__builtin_elementwise_sub_sat(0U, 1U) == 0U);
 static_assert(__builtin_bit_cast(unsigned, __builtin_elementwise_sub_sat((vector4char){5, 4, 3, 2}, (vector4char){1, 1, 1, 1})) == (LITTLE_END ? 0x01020304 : 0x04030201));
 static_assert(__builtin_bit_cast(unsigned, __builtin_elementwise_sub_sat((vector4uchar){5, 4, 3, 2}, (vector4uchar){1, 1, 1, 1})) == (LITTLE_END ? 0x01020304U : 0x04030201U));
 static_assert(__builtin_bit_cast(unsigned long long, __builtin_elementwise_sub_sat((vector4short){(short)0x8000, (short)0x8001, (short)0x8002, (short)0x8003}, (vector4short){7, 8, 9, 10}) == (LITTLE_END ? 0x8000800080008000 : 0x8000800080008000)));
+
+static_assert(__builtin_elementwise_max(1, 2) == 2);
+static_assert(__builtin_elementwise_max(-1, 1) == 1);
+static_assert(__builtin_elementwise_max(1U, 2U) == 2U);
+static_assert(__builtin_elementwise_max(~0U, 0U) == ~0U);
+static_assert(__builtin_bit_cast(unsigned, __builtin_elementwise_max((vector4char){1, -2, 3, -4}, (vector4char){4, -3, 2, -1})) == (LITTLE_END ? 0xFF03FE04 : 0x04FE03FF ));
+static_assert(__builtin_bit_cast(unsigned, __builtin_elementwise_max((vector4uchar){1, 2, 3, 4}, (vector4uchar){4, 3, 2, 1})) == 0x04030304U);
+static_assert(__builtin_bit_cast(unsigned long long, __builtin_elementwise_max((vector4short){1, -2, 3, -4}, (vector4short){4, -3, 2, -1})) == (LITTLE_END ? 0xFFFF0003FFFE0004 : 0x0004FFFE0003FFFF));
+
+static_assert(__builtin_elementwise_min(1, 2) == 1);
+static_assert(__builtin_elementwise_min(-1, 1) == -1);
+static_assert(__builtin_elementwise_min(1U, 2U) == 1U);
+static_assert(__builtin_elementwise_min(~0U, 0U) == 0U);
+static_assert(__builtin_bit_cast(unsigned, __builtin_elementwise_min((vector4char){1, -2, 3, -4}, (vector4char){4, -3, 2, -1})) == (LITTLE_END ? 0xFC02FD01 : 0x01FD02FC));
+static_assert(__builtin_bit_cast(unsigned, __builtin_elementwise_min((vector4uchar){1, 2, 3, 4}, (vector4uchar){4, 3, 2, 1})) == 0x01020201U);
+static_assert(__builtin_bit_cast(unsigned long long, __builtin_elementwise_min((vector4short){1, -2, 3, -4}, (vector4short){4, -3, 2, -1})) == (LITTLE_END ? 0xFFFC0002FFFD0001 : 0x0001FFFD0002FFFC));