[Clang] Update typechecking of builtin elementwise ternary math operators (#155620)

For scalars we directly compare their unqualified types. But even if we
compare unqualified vector types, a difference in qualifiers in the
element types can make the vector types be considered not equal. For
example, vector of 4 'const float' values vs vector of 4 'float' values.
So we compare unqualified types of their elements and number of
elements.

Fixes #155405

Author: ckoparkar

clang/docs/ReleaseNotes.rst

@@ -286,6 +286,9 @@ Bug Fixes in This Version
   calls another function that requires target features not enabled in the caller. This
   prevents a fatal error in the backend.
 - Fixed scope of typedefs present inside a template class. (#GH91451)
+- Builtin elementwise operators now accept vector arguments that have different
+  qualifiers on their elements. For example, vector of 4 ``const float`` values
+  and vector of 4 ``float`` values. (#GH155405)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

clang/lib/Sema/SemaChecking.cpp

@@ -15870,6 +15870,54 @@ static bool checkBuiltinVectorMathMixedEnums(Sema &S, Expr *LHS, Expr *RHS,
   return false;
 }
 
+/// Check if all arguments have the same type. If the types don't match, emit an
+/// error message and return true. Otherwise return false.
+///
+/// For scalars we directly compare their unqualified types. But even if we
+/// compare unqualified vector types, a difference in qualifiers in the element
+/// types can make the vector types be considered not equal. For example,
+/// vector of 4 'const float' values vs vector of 4 'float' values.
+/// So we compare unqualified types of their elements and number of elements.
+static bool checkBuiltinVectorMathArgTypes(Sema &SemaRef,
+                                           ArrayRef<Expr *> Args) {
+  assert(!Args.empty() && "Should have at least one argument.");
+
+  Expr *Arg0 = Args.front();
+  QualType Ty0 = Arg0->getType();
+
+  auto EmitError = [&](Expr *ArgI) {
+    SemaRef.Diag(Arg0->getBeginLoc(),
+                 diag::err_typecheck_call_different_arg_types)
+        << Arg0->getType() << ArgI->getType();
+  };
+
+  // Compare scalar types.
+  if (!Ty0->isVectorType()) {
+    for (Expr *ArgI : Args.drop_front())
+      if (!SemaRef.Context.hasSameUnqualifiedType(Ty0, ArgI->getType())) {
+        EmitError(ArgI);
+        return true;
+      }
+
+    return false;
+  }
+
+  // Compare vector types.
+  const auto *Vec0 = Ty0->castAs<VectorType>();
+  for (Expr *ArgI : Args.drop_front()) {
+    const auto *VecI = ArgI->getType()->getAs<VectorType>();
+    if (!VecI ||
+        !SemaRef.Context.hasSameUnqualifiedType(Vec0->getElementType(),
+                                                VecI->getElementType()) ||
+        Vec0->getNumElements() != VecI->getNumElements()) {
+      EmitError(ArgI);
+      return true;
+    }
+  }
+
+  return false;
+}
+
 std::optional<QualType>
 Sema::BuiltinVectorMath(CallExpr *TheCall,
                         EltwiseBuiltinArgTyRestriction ArgTyRestr) {
@@ -15891,15 +15939,12 @@ Sema::BuiltinVectorMath(CallExpr *TheCall,
 
   SourceLocation LocA = Args[0]->getBeginLoc();
   QualType TyA = Args[0]->getType();
-  QualType TyB = Args[1]->getType();
 
   if (checkMathBuiltinElementType(*this, LocA, TyA, ArgTyRestr, 1))
     return std::nullopt;
 
-  if (!Context.hasSameUnqualifiedType(TyA, TyB)) {
-    Diag(LocA, diag::err_typecheck_call_different_arg_types) << TyA << TyB;
+  if (checkBuiltinVectorMathArgTypes(*this, Args))
     return std::nullopt;
-  }
 
   TheCall->setArg(0, Args[0]);
   TheCall->setArg(1, Args[1]);
@@ -15934,17 +15979,11 @@ bool Sema::BuiltinElementwiseTernaryMath(
       return true;
   }
 
-  TheCall->setArg(0, Args[0]);
-  for (int I = 1; I < 3; ++I) {
-    if (Args[0]->getType().getCanonicalType() !=
-        Args[I]->getType().getCanonicalType()) {
-      return Diag(Args[0]->getBeginLoc(),
-                  diag::err_typecheck_call_different_arg_types)
-             << Args[0]->getType() << Args[I]->getType();
-    }
+  if (checkBuiltinVectorMathArgTypes(*this, Args))
+    return true;
 
+  for (int I = 0; I < 3; ++I)
     TheCall->setArg(I, Args[I]);
-  }
 
   TheCall->setType(Args[0]->getType());
   return false;

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

@@ -5,6 +5,7 @@ typedef double double4 __attribute__((ext_vector_type(4)));
 typedef float float2 __attribute__((ext_vector_type(2)));
 typedef float float3 __attribute__((ext_vector_type(3)));
 typedef float float4 __attribute__((ext_vector_type(4)));
+typedef const float cfloat4 __attribute__((ext_vector_type(4)));
 
 typedef int int2 __attribute__((ext_vector_type(2)));
 typedef int int3 __attribute__((ext_vector_type(3)));
@@ -1330,16 +1331,32 @@ void test_builtin_elementwise_fsh(int i32, int2 v2i32, short i16, int3 v3i32,
     // expected-error@-1 {{arguments are of different types ('int3' (vector of 3 'int' values) vs 'int2' (vector of 2 'int' values))}}
 }
 
+// Tests corresponding to GitHub issues #141397 and #155405.
+// Type mismatch error when 'builtin-elementwise-math' arguments have
+// different qualifiers, this should be well-formed.
 typedef struct {
   float3 b;
 } struct_float3;
-// This example uncovered a bug #141397 :
-// Type mismatch error when 'builtin-elementwise-math' arguments have different qualifiers, this should be well-formed
+
 float3 foo(float3 a,const struct_float3* hi) {
   float3 b = __builtin_elementwise_max((float3)(0.0f), a);
   return __builtin_elementwise_pow(b, hi->b.yyy);
 }
 
+float3 baz(float3 a, const struct_float3* hi) {
+  return __builtin_elementwise_fma(a, a, hi->b);
+}
+
+cfloat4 qux(cfloat4 x, float4 y, float4 z) {
+  float a = __builtin_elementwise_fma(x[0],y[0],z[0]);
+  return __builtin_elementwise_fma(x,y,z);
+}
+
+cfloat4 quux(cfloat4 x, float4 y) {
+  float a = __builtin_elementwise_pow(x[0],y[0]);
+  return __builtin_elementwise_pow(x,y);
+}
+
 void test_builtin_elementwise_ctlz(int i32, int2 v2i32, short i16,
                                    double f64, double2 v2f64) {
   f64 = __builtin_elementwise_ctlz(f64);