[v3] aarch64: Add fp8 scalar types

diff --git a/gcc/config/aarch64/aarch64-builtins.cc b/gcc/config/aarch64/aarch64-builtins.cc
index eb878b933fe..7d17df05a0f 100644
--- a/gcc/config/aarch64/aarch64-builtins.cc
+++ b/gcc/config/aarch64/aarch64-builtins.cc
@@ -961,6 +961,11 @@  static GTY(()) tree aarch64_simd_intOI_type_node = NULL_TREE;
 static GTY(()) tree aarch64_simd_intCI_type_node = NULL_TREE;
 static GTY(()) tree aarch64_simd_intXI_type_node = NULL_TREE;
 
+/* The user-visible __mfp8 type, and a pointer to that type.  Used
+   across the back-end.  */
+tree aarch64_mfp8_type_node = NULL_TREE;
+tree aarch64_mfp8_ptr_type_node = NULL_TREE;
+
 /* The user-visible __fp16 type, and a pointer to that type.  Used
    across the back-end.  */
 tree aarch64_fp16_type_node = NULL_TREE;
@@ -1721,6 +1726,19 @@  aarch64_init_builtin_rsqrt (void)
   }
 }
 
+/* Initialize the backend type that supports the user-visible __mfp8
+   type and its relative pointer type.  */
+
+static void
+aarch64_init_fp8_types (void)
+{
+  aarch64_mfp8_type_node = make_unsigned_type (8);
+  SET_TYPE_MODE (aarch64_mfp8_type_node, QImode);
+
+  lang_hooks.types.register_builtin_type (aarch64_mfp8_type_node, "__mfp8");
+  aarch64_mfp8_ptr_type_node = build_pointer_type (aarch64_mfp8_type_node);
+}
+
 /* Initialize the backend types that support the user-visible __fp16
    type, also initialize a pointer to that type, to be used when
    forming HFAs.  */
@@ -2125,6 +2143,8 @@  aarch64_general_init_builtins (void)
 {
   aarch64_init_fpsr_fpcr_builtins ();
 
+  aarch64_init_fp8_types ();
+
   aarch64_init_fp16_types ();
 
   aarch64_init_bf16_types ();
diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
index 92763d403c7..0ac00027502 100644
--- a/gcc/config/aarch64/aarch64.cc
+++ b/gcc/config/aarch64/aarch64.cc
@@ -22467,6 +22467,10 @@  aarch64_mangle_type (const_tree type)
 	return "Dh";
     }
 
+  /* Modal 8 bit floating point types.  */
+  if (TYPE_MAIN_VARIANT (type) == aarch64_mfp8_type_node)
+    return "u6__mfp8";
+
   /* Mangle AArch64-specific internal types.  TYPE_NAME is non-NULL_TREE for
      builtin types.  */
   if (TYPE_NAME (type) != NULL)
@@ -22481,6 +22485,29 @@  aarch64_mangle_type (const_tree type)
   return NULL;
 }
 
+/* Implement TARGET_INVALID_CONVERSION.  */
+
+static const char *
+aarch64_invalid_conversion (const_tree fromtype, const_tree totype)
+{
+  /* Do not allow conversions to/from FP8. But do allow conversions between
+     volatile and const variants of __mfp8. */
+  bool fromtype_is_fp8
+      = (TYPE_MAIN_VARIANT (fromtype) == aarch64_mfp8_type_node);
+  bool totype_is_fp8 = (TYPE_MAIN_VARIANT (totype) == aarch64_mfp8_type_node);
+
+  if (fromtype_is_fp8 && totype_is_fp8)
+    return NULL;
+
+  if (fromtype_is_fp8)
+    return N_ ("invalid conversion from type %<mfloat8_t%>");
+  if (totype_is_fp8)
+    return N_ ("invalid conversion to type %<mfloat8_t%>");
+
+  /* Conversion allowed.  */
+  return NULL;
+}
+
 /* Implement TARGET_VERIFY_TYPE_CONTEXT.  */
 
 static bool
@@ -29031,8 +29058,20 @@  aarch64_stack_protect_guard (void)
   return NULL_TREE;
 }
 
-/* Return the diagnostic message string if the binary operation OP is
-   not permitted on TYPE1 and TYPE2, NULL otherwise.  */
+/* Implement TARGET_INVALID_UNARY_OP.  */
+
+static const char *
+aarch64_invalid_unary_op (int op, const_tree type)
+{
+  /* Reject all single-operand operations on __mfp8 except for &.  */
+  if (TYPE_MAIN_VARIANT (type) == aarch64_mfp8_type_node && op != ADDR_EXPR)
+    return N_ ("operation not permitted on type %<mfloat8_t%>");
+
+  /* Operation allowed.  */
+  return NULL;
+}
+
+/* Implement TARGET_INVALID_BINARY_OP.  */
 
 static const char *
 aarch64_invalid_binary_op (int op ATTRIBUTE_UNUSED, const_tree type1,
@@ -29046,6 +29085,11 @@  aarch64_invalid_binary_op (int op ATTRIBUTE_UNUSED, const_tree type1,
 	  != aarch64_sve::builtin_type_p (type2)))
     return N_("cannot combine GNU and SVE vectors in a binary operation");
 
+  /* Reject all 2-operand operations on __mfp8.  */
+  if (TYPE_MAIN_VARIANT (type1) == aarch64_mfp8_type_node
+      || TYPE_MAIN_VARIANT (type2) == aarch64_mfp8_type_node)
+    return N_ ("operation not permitted on type %<mfloat8_t%>");
+
   /* Operation allowed.  */
   return NULL;
 }
@@ -30763,6 +30807,12 @@  aarch64_libgcc_floating_mode_supported_p
 #undef TARGET_MANGLE_TYPE
 #define TARGET_MANGLE_TYPE aarch64_mangle_type
 
+#undef TARGET_INVALID_CONVERSION
+#define TARGET_INVALID_CONVERSION aarch64_invalid_conversion
+
+#undef TARGET_INVALID_UNARY_OP
+#define TARGET_INVALID_UNARY_OP aarch64_invalid_unary_op
+
 #undef TARGET_INVALID_BINARY_OP
 #define TARGET_INVALID_BINARY_OP aarch64_invalid_binary_op
 
diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
index 2dfb999bea5..7ef82ce3587 100644
--- a/gcc/config/aarch64/aarch64.h
+++ b/gcc/config/aarch64/aarch64.h
@@ -1447,6 +1447,11 @@  extern const char *aarch64_rewrite_mcpu (int argc, const char **argv);
 
 #define ASM_OUTPUT_POOL_EPILOGUE  aarch64_asm_output_pool_epilogue
 
+/* This type is the user-visible __mfp8, and a pointer to that type.  We
+   need it in many places in the backend.  Defined in aarch64-builtins.cc.  */
+extern GTY(()) tree aarch64_mfp8_type_node;
+extern GTY(()) tree aarch64_mfp8_ptr_type_node;
+
 /* This type is the user-visible __fp16, and a pointer to that type.  We
    need it in many places in the backend.  Defined in aarch64-builtins.cc.  */
 extern GTY(()) tree aarch64_fp16_type_node;
diff --git a/gcc/config/aarch64/arm_private_fp8.h b/gcc/config/aarch64/arm_private_fp8.h
index 5668cc24c99..f78702268cb 100644
--- a/gcc/config/aarch64/arm_private_fp8.h
+++ b/gcc/config/aarch64/arm_private_fp8.h
@@ -40,6 +40,8 @@  extern "C"
 {
 #endif
 
+  typedef __mfp8 mfloat8_t;
+
   typedef uint64_t fpm_t;
 
   enum __ARM_FPM_FORMAT
diff --git a/gcc/testsuite/g++.target/aarch64/fp8_mangling.C b/gcc/testsuite/g++.target/aarch64/fp8_mangling.C
new file mode 100644
index 00000000000..1dfcaa71f15
--- /dev/null
+++ b/gcc/testsuite/g++.target/aarch64/fp8_mangling.C
@@ -0,0 +1,44 @@ 
+/* Test that mfloat8_t mangles differently from uint8_t  */
+/* { dg-options "-O1 -march=armv9.4-a+fp8" } */
+
+int
+foo (__mfp8)
+{
+  return 1;
+}
+
+int
+foo (unsigned char)
+{
+  return 2;
+}
+
+int
+bar (__mfp8 x)
+{
+  return foo (x);
+}
+/* { dg-final { scan-assembler-times "\n_Z3fooh:\n" 1 } } */
+/* { dg-final { scan-assembler-times "\n_Z3foou6__mfp8:\n" 1 } } */
+
+constexpr __mfp8 cfp8{};
+
+constexpr int
+fooc (unsigned char)
+{
+  return 3;
+}
+
+constexpr int
+fooc (__mfp8)
+{
+  return 4;
+}
+
+constexpr int
+barc (__mfp8 x)
+{
+  return fooc (x);
+}
+
+static_assert (barc (cfp8) == 4, "constexpr selects incorrect overload");
diff --git a/gcc/testsuite/g++.target/aarch64/fp8_scalar_typecheck_2.C b/gcc/testsuite/g++.target/aarch64/fp8_scalar_typecheck_2.C
new file mode 100644
index 00000000000..61557c95663
--- /dev/null
+++ b/gcc/testsuite/g++.target/aarch64/fp8_scalar_typecheck_2.C
@@ -0,0 +1,381 @@ 
+/* Test that mfloat8_t is only usable with intrinsics, thus not convertible.  */
+/* { dg-do assemble } */
+/* { dg-options "-O1 -march=armv9.4-a+fp8 -Wno-narrowing" } */
+
+#include <arm_neon.h>
+#include <stdint.h>
+#include <type_traits>
+
+mfloat8_t glob_fp8;
+
+int is_an_int;
+uint8_t is_a_uint8;
+int8_t is_an_int8;
+short is_a_short_int;
+float is_a_float;
+double is_a_double;
+
+uint8_t *uint8_ptr;
+
+mfloat8_t
+invalid_from_fp8 (uint16_t __a)
+{
+  mfloat8_t b = __a; /* { dg-error "invalid conversion to type 'mfloat8_t'" } */
+  return b;
+}
+
+uint16_t
+invalid_to_fp8 (mfloat8_t __a)
+{
+  uint16_t b = __a; /*{ dg-error "invalid conversion from type 'mfloat8_t'" } */
+  return b;
+}
+
+mfloat8_t
+foo1 (void)
+{
+  return (mfloat8_t)0x1234; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+}
+
+mfloat8_t
+foo2 (void)
+{
+  return (mfloat8_t)(short)0x1234; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+}
+
+mfloat8_t
+footest (mfloat8_t scalar0)
+{
+
+  /* Initialisation  */
+
+  mfloat8_t scalar1_1;
+  mfloat8_t scalar1_2 = glob_fp8;
+  mfloat8_t scalar1_3
+      = 0; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar1_4
+      = 0.1; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar1_5
+      = is_a_float; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar1_6
+      = is_an_int; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar1_8
+      = is_a_double; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar1_9 = is_a_short_int; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar1_10
+      = is_a_uint8; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar1_11
+      = is_an_int8; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+
+  int initi_1_1
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  float initi_1_2
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  short initi_1_4
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  double initi_1_5
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  uint8_t initi_1_6
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  int8_t initi_1_7
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+
+  mfloat8_t scalar2_1 = {};
+  mfloat8_t scalar2_2 = { glob_fp8 };
+  mfloat8_t scalar2_3
+      = { 0 }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar2_4
+      = { 0.1 }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar2_5 = {
+    is_a_float /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  };
+  mfloat8_t scalar2_6 = {
+    is_an_int /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  };
+  mfloat8_t scalar2_8 = {
+    is_a_double /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  };
+  mfloat8_t scalar2_9 = {
+    is_a_short_int /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  };
+  mfloat8_t scalar2_10 = {
+    is_a_uint8 /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  };
+  mfloat8_t scalar2_11 = {
+    is_an_int8 /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  };
+
+  int initi_2_1 = {
+    glob_fp8 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  };
+  float initi_2_2 = {
+    glob_fp8 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  };
+  short initi_2_4 = {
+    glob_fp8 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  };
+  double initi_2_5 = {
+    glob_fp8 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  };
+  uint8_t initi_2_6 = {
+    glob_fp8 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  };
+  int8_t initi_2_7 = {
+    glob_fp8 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  };
+
+  /* Assignments.  */
+
+  glob_fp8 = glob_fp8;
+  glob_fp8 = 0;	  /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  glob_fp8 = 0.1; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  glob_fp8
+      = is_a_float; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  glob_fp8
+      = is_an_int; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  glob_fp8
+      = is_a_double; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  glob_fp8 = is_a_short_int; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  glob_fp8
+      = is_a_uint8; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  glob_fp8
+      = is_an_int8; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+
+  is_an_int
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  is_a_float
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  is_a_double
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  is_a_short_int
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  is_a_uint8
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  is_an_int8
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+
+  /* Casting.  */
+
+  (void)glob_fp8;
+  (mfloat8_t) glob_fp8;
+
+  (int)glob_fp8;   /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  (float)glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  (double)
+      glob_fp8;	   /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  (short)glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  (uint8_t)
+      glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  (int8_t)
+      glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+
+  (mfloat8_t)
+      is_an_int; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t)
+      is_a_float; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t)
+      is_a_double; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t) is_a_short_int; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t)
+      is_a_uint8; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t)
+      is_an_int8; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+
+  /* Compound literals.  */
+
+  (mfloat8_t){};
+  (mfloat8_t){ glob_fp8 };
+  (mfloat8_t){ 0 }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t){
+    0.1 /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  }; 
+  (mfloat8_t){
+    is_a_float /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  };
+  (mfloat8_t){
+    is_an_int /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  };
+  (mfloat8_t){
+    is_a_double /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  };
+  (mfloat8_t){
+    is_a_short_int /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  };
+  (mfloat8_t){
+    is_a_uint8 /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  };
+  (mfloat8_t){
+    is_an_int8 /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  };
+
+  (int){
+    glob_fp8 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  };
+  (float){
+    glob_fp8 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  };
+  (double){
+    glob_fp8 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  };
+  (short){
+    glob_fp8 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  };
+  (uint8_t){
+    glob_fp8 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  };
+  (int8_t){
+    glob_fp8 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  };
+
+  /* Arrays and Structs.  */
+
+  typedef mfloat8_t array_type[2];
+  extern mfloat8_t extern_array[];
+
+  mfloat8_t array[2];
+  mfloat8_t zero_length_array[0];
+  mfloat8_t empty_init_array[] = {};
+  typedef mfloat8_t some_other_type[is_an_int];
+
+  struct struct1
+  {
+    mfloat8_t a;
+  };
+
+  union union1
+  {
+    mfloat8_t a;
+  };
+
+  /* Addressing and dereferencing.  */
+
+  mfloat8_t *fp8_ptr = &scalar0;
+  scalar0 = *fp8_ptr;
+
+  /* Pointer assignment.  */
+
+  mfloat8_t *fp8_ptr2 = fp8_ptr;
+  mfloat8_t *fp8_ptr3 = array;
+
+  /* Pointer arithmetic.  */
+
+  ++fp8_ptr;
+  --fp8_ptr;
+  fp8_ptr++;
+  fp8_ptr--;
+  fp8_ptr += 1;
+  fp8_ptr -= 1;
+  fp8_ptr - fp8_ptr2;
+  fp8_ptr = &fp8_ptr3[0];
+  fp8_ptr = &fp8_ptr3[1];
+
+  /* Simple comparison.  */
+  scalar0
+      > glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  glob_fp8
+      == scalar0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 > is_a_float; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  is_a_float
+      == scalar0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 > 0;	  /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  0 == scalar0;	  /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 > 0.1;  /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  0.1 == scalar0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0
+      > is_an_int; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  is_an_int
+      == scalar0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+
+  /* Pointer comparison.  */
+
+  fp8_ptr == &scalar0;
+  fp8_ptr != &scalar0;
+  fp8_ptr < &scalar0;
+  fp8_ptr <= &scalar0;
+  fp8_ptr > &scalar0;
+  fp8_ptr >= &scalar0;
+  fp8_ptr == fp8_ptr2;
+  fp8_ptr != fp8_ptr2;
+  fp8_ptr < fp8_ptr2;
+  fp8_ptr <= fp8_ptr2;
+  fp8_ptr > fp8_ptr2;
+  fp8_ptr >= fp8_ptr2;
+
+  /* Conditional expressions.  */
+
+  0 ? scalar0 : scalar0;
+  0 ? scalar0 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+    : is_a_float;
+  0 ? is_a_float
+    : scalar0;	   /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  0 ? scalar0 : 0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  0 ? 0 : scalar0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  0 ? 0.1
+    : scalar0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  0 ? scalar0  /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+    : 0.1;
+  0 ? fp8_ptr : fp8_ptr2;
+  0 ? fp8_ptr : uint8_ptr; /* { dg-error {conditional expression between distinct pointer types} } */
+  0 ? uint8_ptr : fp8_ptr; /* { dg-error {conditional expression between distinct pointer types} } */
+
+  scalar0 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+      ? scalar0
+      : scalar0;
+  scalar0 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+      ? is_a_float
+      : scalar0;
+  scalar0 ? scalar0 : is_a_float;    /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 ? is_a_float : is_a_float; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+
+  /* Unary operators.  */
+
+  +scalar0; /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  -scalar0; /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  ~scalar0; /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  !scalar0; /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  *scalar0; /* { dg-error {invalid type argument of unary} } */
+  __real scalar0; /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  __imag scalar0; /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  ++scalar0; /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  --scalar0; /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  scalar0++; /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  scalar0--; /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+
+  /* Binary arithmetic operations.  */
+
+  scalar0 = glob_fp8 + scalar1_2; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 = glob_fp8 + *fp8_ptr;  /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 = glob_fp8
+	    + 0.1; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 = glob_fp8
+	    + 0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 = glob_fp8 + is_a_float; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+
+  glob_fp8 + glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  glob_fp8 - glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  glob_fp8 * glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  glob_fp8 / glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  glob_fp8 && glob_fp8; /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  glob_fp8 || glob_fp8; /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+
+  return scalar0;
+}
+
+/* Check that function decls for mfloat8_t and unsigned char differ */
+
+mfloat8_t extern_fn1(void);
+unsigned char extern_fn1(void); /* { dg-error {ambiguating new declaration of 'unsigned char extern_fn1\(\)'} } */
+
+mfloat8_t extern_fn2(void);
+uint8_t extern_fn2(void); /* { dg-error {ambiguating new declaration of 'uint8_t extern_fn2\(\)} } */
+
+unsigned char extern_fn3(void);
+mfloat8_t extern_fn3(void); /* { dg-error {ambiguating new declaration of 'mfloat8_t extern_fn3\(\)} } */
+
+uint8_t extern_fn4(void);
+mfloat8_t extern_fn4(void); /* { dg-error {ambiguating new declaration of 'mfloat8_t extern_fn4\(\)} } */
+
+/* Check that the type conforms to the contract */
+static_assert(!std::is_integral<__mfp8>(), "not integral");
+static_assert(!std::is_signed<__mfp8>(), "not signed");
+static_assert(!std::is_unsigned<__mfp8>(), "not unsigned");
diff --git a/gcc/testsuite/gcc.target/aarch64/fp8_scalar_1.c b/gcc/testsuite/gcc.target/aarch64/fp8_scalar_1.c
new file mode 100644
index 00000000000..1bc2ac26b2a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/fp8_scalar_1.c
@@ -0,0 +1,134 @@ 
+/* Test the fp8 ACLE intrinsics family.  */
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=armv9.4-a+fp8" } */
+/* { dg-final { check-function-bodies "**" "" "" } } */
+
+#include <arm_neon.h>
+
+/*
+**stacktest1:
+**	sub	sp, sp, #16
+**	and	w0, w0, 255
+**	strb	w0, \[sp, 15\]
+**	ldrb	w0, \[sp, 15\]
+**	add	sp, sp, 16
+**	ret
+*/
+mfloat8_t
+stacktest1 (mfloat8_t __a)
+{
+  volatile mfloat8_t b = __a;
+  return b;
+}
+
+/*
+**fp8_mov_ww:
+**	dup	b1, v2.b\[0\]
+**	ret
+*/
+void
+fp8_mov_ww (void)
+{
+  register mfloat8_t x asm ("h2");
+  register mfloat8_t y asm ("h1");
+  asm volatile ("" : "=w"(x));
+  y = x;
+  asm volatile ("" ::"w"(y));
+}
+
+/*
+**fp8_mov_rw:
+**	dup	v1.8b, w1
+**	ret
+*/
+void
+fp8_mov_rw (void)
+{
+  register mfloat8_t x asm ("w1");
+  register mfloat8_t y asm ("h1");
+  asm volatile ("" : "=r"(x));
+  y = x;
+  asm volatile ("" ::"w"(y));
+}
+
+/*
+**fp8_mov_wr:
+**	umov	w1, v1.b\[0\]
+**	ret
+*/
+void
+fp8_mov_wr (void)
+{
+  register mfloat8_t x asm ("h1");
+  register mfloat8_t y asm ("w1");
+  asm volatile ("" : "=w"(x));
+  y = x;
+  asm volatile ("" ::"r"(y));
+}
+
+/*
+**fp8_mov_rr:
+**	mov	w1, w2
+**	ret
+*/
+void
+fp8_mov_rr (void)
+{
+  register mfloat8_t x asm ("w2");
+  register mfloat8_t y asm ("w1");
+  asm volatile ("" : "=r"(x));
+  y = x;
+  asm volatile ("" ::"r"(y));
+}
+
+/*
+**fp8_mov_rm:
+**	strb	w2, \[x0\]
+**	ret
+*/
+void
+fp8_mov_rm (mfloat8_t *ptr)
+{
+  register mfloat8_t x asm ("w2");
+  asm volatile ("" : "=r"(x));
+  *ptr = x;
+}
+
+/*
+**fp8_mov_mr:
+**	ldrb	w2, \[x0\]
+**	ret
+*/
+void
+fp8_mov_mr (mfloat8_t *ptr)
+{
+  register mfloat8_t y asm ("w2");
+  y = *ptr;
+  asm volatile ("" ::"r"(y));
+}
+
+/*
+**fp8_str_r:
+**	str	b2, \[x0\]
+**	ret
+*/
+void
+fp8_str_r (mfloat8_t *ptr)
+{
+  register mfloat8_t x asm ("v2");
+  asm volatile ("" : "=w"(x));
+  *ptr = x;
+}
+
+/*
+**fp8_ldr_r:
+**	ldr	b2, \[x0\]
+**	ret
+*/
+void
+fp8_ldr_r (mfloat8_t *ptr)
+{
+  register mfloat8_t y asm ("v2");
+  y = *ptr;
+  asm volatile ("" ::"w"(y));
+}
diff --git a/gcc/testsuite/gcc.target/aarch64/fp8_scalar_typecheck_1.c b/gcc/testsuite/gcc.target/aarch64/fp8_scalar_typecheck_1.c
new file mode 100644
index 00000000000..9169f40c4b7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/fp8_scalar_typecheck_1.c
@@ -0,0 +1,356 @@ 
+/* Test that there is no conversion between ints and mfloat8_t.  */
+/* { dg-do assemble } */
+/* { dg-options "-O1 -march=armv9.4-a+fp8" } */
+
+#include <arm_neon.h>
+#include <stdint.h>
+
+mfloat8_t glob_fp8;
+
+int is_an_int;
+uint8_t is_a_uint8;
+int8_t is_an_int8;
+short is_a_short_int;
+float is_a_float;
+double is_a_double;
+
+uint8_t *uint8_ptr;
+
+mfloat8_t
+invalid_from_fp8 (uint16_t __a)
+{
+  mfloat8_t b = __a; // { dg-error "invalid conversion to type 'mfloat8_t'" }
+  return b;
+}
+
+uint16_t
+invalid_to_fp8 (mfloat8_t __a)
+{
+  uint16_t b = __a; // { dg-error "invalid conversion from type 'mfloat8_t'" }
+  return b;
+}
+
+mfloat8_t
+foo1 (void)
+{
+  return (mfloat8_t)0x1234; // { dg-error {invalid conversion to type 'mfloat8_t'} }
+}
+mfloat8_t
+foo2 (void)
+{
+  return (mfloat8_t)(short)0x1234; // { dg-error {invalid conversion to type 'mfloat8_t'} }
+}
+
+mfloat8_t
+footest (mfloat8_t scalar0)
+{
+
+  /* Initialisation  */
+
+  mfloat8_t scalar1_1;
+  mfloat8_t scalar1_2 = glob_fp8;
+  mfloat8_t scalar1_3 = 0; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar1_4
+      = 0.1; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar1_5
+      = is_a_float; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar1_6
+      = is_an_int; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar1_8
+      = is_a_double; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar1_9
+      = is_a_short_int; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar1_10
+      = is_a_uint8; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar1_11
+      = is_an_int8; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+
+  int initi_1_1
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  float initi_1_2
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  short initi_1_4
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  double initi_1_5
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  uint8_t initi_1_6
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  int8_t initi_1_7
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+
+  mfloat8_t scalar2_1 = {};
+  mfloat8_t scalar2_2 = { glob_fp8 };
+  mfloat8_t scalar2_3
+      = { 0 }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar2_4
+      = { 0.1 }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar2_5
+      = { is_a_float }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar2_6
+      = { is_an_int }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar2_8 = {
+    is_a_double
+  }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar2_9 = {
+    is_a_short_int
+  }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar2_10
+      = { is_a_uint8 }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  mfloat8_t scalar2_11
+      = { is_an_int8 }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+
+  int initi_2_1
+      = { glob_fp8 }; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  float initi_2_2
+      = { glob_fp8 }; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  short initi_2_4
+      = { glob_fp8 }; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  double initi_2_5
+      = { glob_fp8 }; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  uint8_t initi_2_6
+      = { glob_fp8 }; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  int8_t initi_2_7
+      = { glob_fp8 }; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+
+  /* Assignments.  */
+
+  glob_fp8 = glob_fp8;
+  glob_fp8 = 0;	  /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  glob_fp8 = 0.1; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  glob_fp8
+      = is_a_float;	/* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  glob_fp8 = is_an_int; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  glob_fp8
+      = is_a_double; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  glob_fp8
+      = is_a_short_int; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  glob_fp8
+      = is_a_uint8; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  glob_fp8
+      = is_an_int8; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+
+  is_an_int
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  is_a_float
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  is_a_double
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  is_a_short_int
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  is_a_uint8
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  is_an_int8
+      = glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+
+  /* Casting.  */
+
+  (void)glob_fp8;
+  (mfloat8_t) glob_fp8;
+
+  (int)glob_fp8;     /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  (float)glob_fp8;   /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  (double)glob_fp8;  /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  (short)glob_fp8;   /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  (uint8_t)glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  (int8_t)glob_fp8;  /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+
+  (mfloat8_t) is_an_int;	/* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t) is_a_float;	/* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t) is_a_double; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t)
+      is_a_short_int;  /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t) is_a_uint8; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t) is_an_int8; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+
+  /* Compound literals.  */
+
+  (mfloat8_t){};
+  (mfloat8_t){ glob_fp8 };
+  (mfloat8_t){ 0 };   /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t){ 0.1 }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t){
+    is_a_float
+  }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t){
+    is_an_int
+  }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t){
+    is_a_double
+  }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t){
+    is_a_short_int
+  }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t){
+    is_a_uint8
+  }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+  (mfloat8_t){
+    is_an_int8
+  }; /* { dg-error {invalid conversion to type 'mfloat8_t'} } */
+
+  (int){ glob_fp8 }; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  (float){
+    glob_fp8
+  }; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  (double){
+    glob_fp8
+  }; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  (short){
+    glob_fp8
+  }; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  (uint8_t){
+    glob_fp8
+  }; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  (int8_t){
+    glob_fp8
+  }; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+
+  /* Arrays and Structs.  */
+
+  typedef mfloat8_t array_type[2];
+  extern mfloat8_t extern_array[];
+
+  mfloat8_t array[2];
+  mfloat8_t zero_length_array[0];
+  mfloat8_t empty_init_array[] = {};
+  typedef mfloat8_t some_other_type[is_an_int];
+
+  struct struct1
+  {
+    mfloat8_t a;
+  };
+
+  union union1
+  {
+    mfloat8_t a;
+  };
+
+  /* Addressing and dereferencing.  */
+
+  mfloat8_t *fp8_ptr = &scalar0;
+  scalar0 = *fp8_ptr;
+
+  /* Pointer assignment.  */
+
+  mfloat8_t *fp8_ptr2 = fp8_ptr;
+  mfloat8_t *fp8_ptr3 = array;
+
+  /* Pointer arithmetic.  */
+
+  ++fp8_ptr;
+  --fp8_ptr;
+  fp8_ptr++;
+  fp8_ptr--;
+  fp8_ptr += 1;
+  fp8_ptr -= 1;
+  fp8_ptr - fp8_ptr2;
+  fp8_ptr = &fp8_ptr3[0];
+  fp8_ptr = &fp8_ptr3[1];
+
+  /* Simple comparison.  */
+  scalar0 > glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  glob_fp8
+      == scalar0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 > is_a_float; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  is_a_float
+      == scalar0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 > 0;	  /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  0 == scalar0;	  /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 > 0.1;  /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  0.1 == scalar0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0
+      > is_an_int; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  is_an_int
+      == scalar0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+
+  /* Pointer comparison.  */
+
+  fp8_ptr == &scalar0;
+  fp8_ptr != &scalar0;
+  fp8_ptr < &scalar0;
+  fp8_ptr <= &scalar0;
+  fp8_ptr > &scalar0;
+  fp8_ptr >= &scalar0;
+  fp8_ptr == fp8_ptr2;
+  fp8_ptr != fp8_ptr2;
+  fp8_ptr < fp8_ptr2;
+  fp8_ptr <= fp8_ptr2;
+  fp8_ptr > fp8_ptr2;
+  fp8_ptr >= fp8_ptr2;
+
+  /* Conditional expressions.  */
+
+  0 ? scalar0 : scalar0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  0 ? scalar0
+    : is_a_float; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  0 ? is_a_float
+    : scalar0;	     /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  0 ? scalar0 : 0;   /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  0 ? 0 : scalar0;   /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  0 ? 0.1 : scalar0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  0 ? scalar0 : 0.1; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  0 ? fp8_ptr : fp8_ptr2;
+  0 ? fp8_ptr : uint8_ptr; /* { dg-error {pointer type mismatch in conditional expression} } */
+  0 ? uint8_ptr : fp8_ptr; /* { dg-error {pointer type mismatch in conditional expression} } */
+
+  scalar0 ? scalar0 /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+	  : scalar0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 ? is_a_float /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+	  : scalar0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 ? scalar0 : is_a_float; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 ? is_a_float : is_a_float; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+
+  /* Unary operators.  */
+
+  +scalar0;	  /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  -scalar0;	  /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  ~scalar0;	  /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  !scalar0;	  /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  *scalar0;	  /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  __real scalar0; /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  __imag scalar0; /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  ++scalar0;	  /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  --scalar0;	  /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  scalar0++;	  /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+  scalar0--;	  /* { dg-error {operation not permitted on type 'mfloat8_t'} } */
+
+  /* Binary arithmetic operations.  */
+
+  scalar0 = glob_fp8 + scalar1_2; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 = glob_fp8 + *fp8_ptr; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0 = glob_fp8
+	    + 0.1; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0
+      = glob_fp8 + 0; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  scalar0
+      = glob_fp8
+	+ is_a_float; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+
+  glob_fp8 + glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  glob_fp8 - glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  glob_fp8 * glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  glob_fp8 / glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  glob_fp8 && glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+  glob_fp8 || glob_fp8; /* { dg-error {invalid conversion from type 'mfloat8_t'} } */
+
+  return scalar0;
+}
+
+/* Check that function decls for mfloat8_t and unsigned char differ */
+
+mfloat8_t extern_fn1(void);
+unsigned char extern_fn1(void); /* { dg-error {conflicting types for 'extern_fn1'; have 'unsigned char\(void\)'} } */
+
+mfloat8_t extern_fn2(void);
+uint8_t extern_fn2(void); /* { dg-error {conflicting types for 'extern_fn2'; have 'uint8_t\(void\)'} } */
+
+unsigned char extern_fn3(void);
+mfloat8_t extern_fn3(void); /* { dg-error {conflicting types for 'extern_fn3'; have 'mfloat8_t\(void\)'} } */
+
+uint8_t extern_fn4(void);
+mfloat8_t extern_fn4(void); /* { dg-error {conflicting types for 'extern_fn4'; have 'mfloat8_t\(void\)'} } */
+
+void extern_fn5(mfloat8_t);
+void extern_fn5(unsigned char); /* { dg-error {conflicting types for 'extern_fn5'; have 'void\(unsigned char\)'} } */
+
+void extern_fn6(mfloat8_t);
+void extern_fn6(uint8_t); /* { dg-error {conflicting types for 'extern_fn6'; have 'void\(uint8_t\)'} } */