c: Fix bogus vector initialisation error [PR96377]

One of the problems in this PR was that if we had:

  vector_type1 array[] = { vector_value1 };

process_init_element would only treat vector_value1 as initialising
a vector_type1 if they had the same TYPE_MAIN_VARIANT.  This has
several problems:

(1) It gives confusing error messages if the vector types are
    incompatible.  (Tested by gcc.dg/pr96377-1.c.)

(2) It means that we reject code that should be valid with
    -flax-vector-conversions.  (Tested by gcc.dg/pr96377-2.c.)

(3) On arm and aarch64 targets, it means that we reject some
    initializers that mix Advanced SIMD and standard GNU vectors.
    These vectors have traditionally had different TYPE_MAIN_VARIANTs
    because they have different mangling schemes.  (Tested by
    gcc.dg/pr96377-[3-6].c.)

(4) It means that we reject SVE initializers that should be valid.
    (Tested by gcc.target/aarch64/sve/gnu_vectors_[34].c.)

(5) After r11-1741-g:31427b974ed7b7dd54e2 we reject:

      arm_neon_type1 array[] = { k ^ arm_neon_value1 };

    because applying the binary operator to arm_neon_value1 strips
    the "Advanced SIMD type" attributes that were added in that patch.
    Stripping the attributes is problematic for other reasons though,
    so that still needs to be fixed separately.

g++.target/aarch64/sve/gnu_vectors_[34].C already pass.

gcc/c/
	PR c/96377
	* c-typeck.c (process_init_element): Split test for whether to
	recurse into a record, union or array into...
	(initialize_elementwise_p): ...this new function.  Don't recurse
	into a vector type if the initialization value is also a vector.

gcc/testsuite/
	PR c/96377
	* gcc.dg/pr96377-1.c: New test.
	* gcc.dg/pr96377-2.c: Likewise.
	* gcc.dg/pr96377-3.c: Likewise.
	* gcc.dg/pr96377-4.c: Likewise.
	* gcc.dg/pr96377-5.c: Likewise.
	* gcc.dg/pr96377-6.c: Likewise.
	* gcc.target/aarch64/pr96377-1.c: Likewise.
	* gcc.target/aarch64/sve/acle/general-c/gnu_vectors_3.c: Likewise.
	* gcc.target/aarch64/sve/acle/general-c/gnu_vectors_4.c: Likewise.
	* g++.target/aarch64/sve/acle/general-c++/gnu_vectors_3.C: Likewise.
	* g++.target/aarch64/sve/acle/general-c++/gnu_vectors_4.C: Likewise.

gcc/c/c-typeck.c

@@ -9956,6 +9956,47 @@ output_pending_init_elements (int all, struct obstack * braced_init_obstack)
   goto retry;
 }
 
+/* Expression VALUE coincides with the start of type TYPE in a braced
+   initializer.  Return true if we should treat VALUE as initializing
+   the first element of TYPE, false if we should treat it as initializing
+   TYPE as a whole.
+
+   If the initializer is clearly invalid, the question becomes:
+   which choice gives the best error message?  */
+
+static bool
+initialize_elementwise_p (tree type, tree value)
+{
+  if (type == error_mark_node || value == error_mark_node)
+    return false;
+
+  gcc_checking_assert (TYPE_MAIN_VARIANT (type) == type);
+
+  tree value_type = TREE_TYPE (value);
+  if (value_type == error_mark_node)
+    return false;
+
+  /* GNU vectors can be initialized elementwise.  However, treat any
+     kind of vector value as initializing the vector type as a whole,
+     regardless of whether the value is a GNU vector.  Such initializers
+     are valid if and only if they would have been valid in a non-braced
+     initializer like:
+
+	TYPE foo = VALUE;
+
+     so recursing into the vector type would be at best confusing or at
+     worst wrong.  For example, when -flax-vector-conversions is in effect,
+     it's possible to initialize a V8HI from a V4SI, even though the vectors
+     have different element types and different numbers of elements.  */
+  if (gnu_vector_type_p (type))
+    return !VECTOR_TYPE_P (value_type);
+
+  if (AGGREGATE_TYPE_P (type))
+    return type != TYPE_MAIN_VARIANT (value_type);
+
+  return false;
+}
+
 /* Add one non-braced element to the current constructor level.
    This adjusts the current position within the constructor's type.
    This may also start or terminate implicit levels
@@ -10135,11 +10176,7 @@ process_init_element (location_t loc, struct c_expr value, bool implicit,
 	  /* Otherwise, if we have come to a subaggregate,
 	     and we don't have an element of its type, push into it.  */
 	  else if (value.value != NULL_TREE
-		   && value.value != error_mark_node
-		   && TYPE_MAIN_VARIANT (TREE_TYPE (value.value)) != fieldtype
-		   && (fieldcode == RECORD_TYPE || fieldcode == ARRAY_TYPE
-		       || fieldcode == UNION_TYPE
-		       || gnu_vector_type_p (fieldtype)))
+		   && initialize_elementwise_p (fieldtype, value.value))
 	    {
 	      push_init_level (loc, 1, braced_init_obstack);
 	      continue;
@@ -10227,11 +10264,7 @@ process_init_element (location_t loc, struct c_expr value, bool implicit,
 	  /* Otherwise, if we have come to a subaggregate,
 	     and we don't have an element of its type, push into it.  */
 	  else if (value.value != NULL_TREE
-		   && value.value != error_mark_node
-		   && TYPE_MAIN_VARIANT (TREE_TYPE (value.value)) != fieldtype
-		   && (fieldcode == RECORD_TYPE || fieldcode == ARRAY_TYPE
-		       || fieldcode == UNION_TYPE
-		       || gnu_vector_type_p (fieldtype)))
+		   && initialize_elementwise_p (fieldtype, value.value))
 	    {
 	      push_init_level (loc, 1, braced_init_obstack);
 	      continue;
@@ -10270,11 +10303,7 @@ process_init_element (location_t loc, struct c_expr value, bool implicit,
 	  /* Otherwise, if we have come to a subaggregate,
 	     and we don't have an element of its type, push into it.  */
 	  else if (value.value != NULL_TREE
-		   && value.value != error_mark_node
-		   && TYPE_MAIN_VARIANT (TREE_TYPE (value.value)) != elttype
-		   && (eltcode == RECORD_TYPE || eltcode == ARRAY_TYPE
-		       || eltcode == UNION_TYPE
-		       || gnu_vector_type_p (elttype)))
+		   && initialize_elementwise_p (elttype, value.value))
 	    {
 	      push_init_level (loc, 1, braced_init_obstack);
 	      continue;

gcc/testsuite/g++.target/aarch64/sve/acle/general-c++/gnu_vectors_3.C

@@ -0,0 +1,15 @@
+/* { dg-options "-msve-vector-bits=256" } */
+
+#include <arm_sve.h>
+
+typedef uint8_t gnu_uint8_t __attribute__ ((vector_size (32)));
+typedef int8_t gnu_int8_t __attribute__ ((vector_size (32)));
+
+void
+f (svuint8_t sve_u1, svint8_t sve_s1,
+   gnu_uint8_t gnu_u1, gnu_int8_t gnu_s1)
+{
+  gnu_uint8_t arr1[] = { gnu_u1, sve_u1 };
+  gnu_uint8_t arr2[] = { gnu_s1 }; // { dg-error "cannot convert" }
+  gnu_uint8_t arr3[] = { sve_s1 }; // { dg-error "cannot convert" }
+}

gcc/testsuite/g++.target/aarch64/sve/acle/general-c++/gnu_vectors_4.C

@@ -0,0 +1,15 @@
+/* { dg-options "-msve-vector-bits=256 -flax-vector-conversions" } */
+
+#include <arm_sve.h>
+
+typedef uint8_t gnu_uint8_t __attribute__ ((vector_size (32)));
+typedef int8_t gnu_int8_t __attribute__ ((vector_size (32)));
+
+void
+f (svuint8_t sve_u1, svint8_t sve_s1,
+   gnu_uint8_t gnu_u1, gnu_int8_t gnu_s1)
+{
+  gnu_uint8_t arr1[] = { gnu_u1, sve_u1 };
+  gnu_uint8_t arr2[] = { gnu_s1 };
+  gnu_uint8_t arr3[] = { sve_s1 };
+}

gcc/testsuite/gcc.dg/pr96377-1.c

@@ -0,0 +1,32 @@
+/* { dg-options "-fno-lax-vector-conversions" } */
+/* { dg-message "use '-flax-vector-conversions' to permit conversions" "" { target *-*-* } 0 } */
+
+typedef int v4si __attribute__((vector_size(16)));
+typedef short v8hi __attribute__((vector_size(16)));
+
+struct s { v8hi x; v4si y; };
+union u1 { v8hi x; v4si y; };
+union u2 { v4si s; v8hi y; };
+
+void
+foo (v4si i, v8hi h)
+{
+  struct s x1 = { i, i }; // { dg-error "incompatible types when initializing type '__vector" }
+  struct s x2 = { h, h }; // { dg-error "incompatible types" }
+  struct s x3 = { i, h }; // { dg-error "incompatible types" }
+  struct s x4 = { h, i };
+
+  union u1 y1 = { i }; // { dg-error "incompatible types" }
+  union u1 y2 = { h };
+  union u2 y3 = { i };
+  union u2 y4 = { h }; // { dg-error "incompatible types" }
+
+  v4si z1[] = { i, i };
+  v4si z2[] = { i, h }; // { dg-error "incompatible types" }
+  v4si z3[] = { h, i }; // { dg-error "incompatible types" }
+  v4si z4[] = { h, h }; // { dg-error "incompatible types" }
+  v8hi z5[] = { i, i }; // { dg-error "incompatible types" }
+  v8hi z6[] = { i, h }; // { dg-error "incompatible types" }
+  v8hi z7[] = { h, i }; // { dg-error "incompatible types" }
+  v8hi z8[] = { h, h };
+}

gcc/testsuite/gcc.dg/pr96377-2.c

@@ -0,0 +1,31 @@
+/* { dg-options "-flax-vector-conversions" } */
+
+typedef int v4si __attribute__((vector_size(16)));
+typedef short v8hi __attribute__((vector_size(16)));
+
+struct s { v8hi x; v4si y; };
+union u1 { v8hi x; v4si y; };
+union u2 { v4si s; v8hi y; };
+
+void
+foo (v4si i, v8hi h)
+{
+  struct s x1 = { i, i };
+  struct s x2 = { h, h };
+  struct s x3 = { i, h };
+  struct s x4 = { h, i };
+
+  union u1 y1 = { i };
+  union u1 y2 = { h };
+  union u2 y3 = { i };
+  union u2 y4 = { h };
+
+  v4si z1[] = { i, i };
+  v4si z2[] = { i, h };
+  v4si z3[] = { h, i };
+  v4si z4[] = { h, h };
+  v8hi z5[] = { i, i };
+  v8hi z6[] = { i, h };
+  v8hi z7[] = { h, i };
+  v8hi z8[] = { h, h };
+}

gcc/testsuite/gcc.dg/pr96377-3.c

@@ -0,0 +1,33 @@
+/* { dg-do compile { target aarch64*-*-* } } */
+/* { dg-options "-fno-lax-vector-conversions" } */
+/* { dg-message "use '-flax-vector-conversions' to permit conversions" "" { target *-*-* } 0 } */
+
+typedef int v4si __attribute__((vector_size(16)));
+typedef short v8hi __attribute__((vector_size(16)));
+
+struct s { v8hi x; v4si y; };
+union u1 { v8hi x; v4si y; };
+union u2 { v4si s; v8hi y; };
+
+void
+foo (__Int32x4_t i, __Int16x8_t h)
+{
+  struct s x1 = { i, i }; // { dg-error "incompatible types when initializing type '__vector" }
+  struct s x2 = { h, h }; // { dg-error "incompatible types" }
+  struct s x3 = { i, h }; // { dg-error "incompatible types" }
+  struct s x4 = { h, i };
+
+  union u1 y1 = { i }; // { dg-error "incompatible types" }
+  union u1 y2 = { h };
+  union u2 y3 = { i };
+  union u2 y4 = { h }; // { dg-error "incompatible types" }
+
+  v4si z1[] = { i, i };
+  v4si z2[] = { i, h }; // { dg-error "incompatible types" }
+  v4si z3[] = { h, i }; // { dg-error "incompatible types" }
+  v4si z4[] = { h, h }; // { dg-error "incompatible types" }
+  v8hi z5[] = { i, i }; // { dg-error "incompatible types" }
+  v8hi z6[] = { i, h }; // { dg-error "incompatible types" }
+  v8hi z7[] = { h, i }; // { dg-error "incompatible types" }
+  v8hi z8[] = { h, h };
+}

gcc/testsuite/gcc.dg/pr96377-4.c

@@ -0,0 +1,32 @@
+/* { dg-do compile { target aarch64*-*-* } } */
+/* { dg-options "-flax-vector-conversions" } */
+
+typedef int v4si __attribute__((vector_size(16)));
+typedef short v8hi __attribute__((vector_size(16)));
+
+struct s { v8hi x; v4si y; };
+union u1 { v8hi x; v4si y; };
+union u2 { v4si s; v8hi y; };
+
+void
+foo (__Int32x4_t i, __Int16x8_t h)
+{
+  struct s x1 = { i, i };
+  struct s x2 = { h, h };
+  struct s x3 = { i, h };
+  struct s x4 = { h, i };
+
+  union u1 y1 = { i };
+  union u1 y2 = { h };
+  union u2 y3 = { i };
+  union u2 y4 = { h };
+
+  v4si z1[] = { i, i };
+  v4si z2[] = { i, h };
+  v4si z3[] = { h, i };
+  v4si z4[] = { h, h };
+  v8hi z5[] = { i, i };
+  v8hi z6[] = { i, h };
+  v8hi z7[] = { h, i };
+  v8hi z8[] = { h, h };
+}

gcc/testsuite/gcc.dg/pr96377-5.c

@@ -0,0 +1,33 @@
+/* { dg-do compile { target aarch64*-*-* } } */
+/* { dg-options "-fno-lax-vector-conversions" } */
+/* { dg-message "use '-flax-vector-conversions' to permit conversions" "" { target *-*-* } 0 } */
+
+typedef int v4si __attribute__((vector_size(16)));
+typedef short v8hi __attribute__((vector_size(16)));
+
+struct s { __Int16x8_t x; __Int32x4_t y; };
+union u1 { __Int16x8_t x; __Int32x4_t y; };
+union u2 { __Int32x4_t s; __Int16x8_t y; };
+
+void
+foo (v4si i, v8hi h)
+{
+  struct s x1 = { i, i }; // { dg-error "incompatible types when initializing type '__Int16x8_t" }
+  struct s x2 = { h, h }; // { dg-error "incompatible types" }
+  struct s x3 = { i, h }; // { dg-error "incompatible types" }
+  struct s x4 = { h, i };
+
+  union u1 y1 = { i }; // { dg-error "incompatible types" }
+  union u1 y2 = { h };
+  union u2 y3 = { i };
+  union u2 y4 = { h }; // { dg-error "incompatible types" }
+
+  v4si z1[] = { i, i };
+  v4si z2[] = { i, h }; // { dg-error "incompatible types" }
+  v4si z3[] = { h, i }; // { dg-error "incompatible types" }
+  v4si z4[] = { h, h }; // { dg-error "incompatible types" }
+  v8hi z5[] = { i, i }; // { dg-error "incompatible types" }
+  v8hi z6[] = { i, h }; // { dg-error "incompatible types" }
+  v8hi z7[] = { h, i }; // { dg-error "incompatible types" }
+  v8hi z8[] = { h, h };
+}

gcc/testsuite/gcc.dg/pr96377-6.c

@@ -0,0 +1,32 @@
+/* { dg-do compile { target aarch64*-*-* } } */
+/* { dg-options "-flax-vector-conversions" } */
+
+typedef int v4si __attribute__((vector_size(16)));
+typedef short v8hi __attribute__((vector_size(16)));
+
+struct s { __Int16x8_t x; __Int32x4_t y; };
+union u1 { __Int16x8_t x; __Int32x4_t y; };
+union u2 { __Int32x4_t s; __Int16x8_t y; };
+
+void
+foo (v4si i, v8hi h)
+{
+  struct s x1 = { i, i };
+  struct s x2 = { h, h };
+  struct s x3 = { i, h };
+  struct s x4 = { h, i };
+
+  union u1 y1 = { i };
+  union u1 y2 = { h };
+  union u2 y3 = { i };
+  union u2 y4 = { h };
+
+  v4si z1[] = { i, i };
+  v4si z2[] = { i, h };
+  v4si z3[] = { h, i };
+  v4si z4[] = { h, h };
+  v8hi z5[] = { i, i };
+  v8hi z6[] = { i, h };
+  v8hi z7[] = { h, i };
+  v8hi z8[] = { h, h };
+}

gcc/testsuite/gcc.target/aarch64/pr96377-1.c

@@ -0,0 +1,20 @@
+/* { dg-options "" } */
+
+#include <arm_neon.h>
+
+struct aegis128_state {
+ uint8x16_t v[5];
+};
+
+void foo(const void *key, const void *iv, const void *const0, const void *const1)
+{
+ uint8x16_t k = vld1q_u8(key);
+ uint8x16_t kiv = k ^ vld1q_u8(iv);
+ struct aegis128_state st = {{
+  kiv,
+  vld1q_u8(const1),
+  vld1q_u8(const0),
+  k ^ vld1q_u8(const0),
+  k ^ vld1q_u8(const1),
+ }};
+}

gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/gnu_vectors_3.c

@@ -0,0 +1,15 @@
+/* { dg-options "-msve-vector-bits=256" } */
+
+#include <arm_sve.h>
+
+typedef uint8_t gnu_uint8_t __attribute__ ((vector_size (32)));
+typedef int8_t gnu_int8_t __attribute__ ((vector_size (32)));
+
+void
+f (svuint8_t sve_u1, svint8_t sve_s1,
+   gnu_uint8_t gnu_u1, gnu_int8_t gnu_s1)
+{
+  gnu_uint8_t arr1[] = { gnu_u1, sve_u1 };
+  gnu_uint8_t arr2[] = { gnu_s1 }; // { dg-error "incompatible types" }
+  gnu_uint8_t arr3[] = { sve_s1 }; // { dg-error "incompatible types" }
+}

gcc/testsuite/gcc.target/aarch64/sve/acle/general-c/gnu_vectors_4.c

@@ -0,0 +1,15 @@
+/* { dg-options "-msve-vector-bits=256 -flax-vector-conversions" } */
+
+#include <arm_sve.h>
+
+typedef uint8_t gnu_uint8_t __attribute__ ((vector_size (32)));
+typedef int8_t gnu_int8_t __attribute__ ((vector_size (32)));
+
+void
+f (svuint8_t sve_u1, svint8_t sve_s1,
+   gnu_uint8_t gnu_u1, gnu_int8_t gnu_s1)
+{
+  gnu_uint8_t arr1[] = { gnu_u1, sve_u1 };
+  gnu_uint8_t arr2[] = { gnu_s1 };
+  gnu_uint8_t arr3[] = { sve_s1 };
+}