[gcc(refs/vendors/ARM/heads/morello)] Declare all constants with an associated size

[gcc(refs/vendors/ARM/heads/morello)] Declare all constants with an associated size

[Matthew Malcomson]

https://gcc.gnu.org/g:e3653f9e4f8bbd822de3ab7db22a3b10f8a9895d

commit e3653f9e4f8bbd822de3ab7db22a3b10f8a9895d
Author: Matthew Malcomson <matthew.malcomson@arm.com>
Date:   Thu Sep 16 11:33:49 2021 +0100

    Declare all constants with an associated size
    
    For PureCap we have introduced an indirection layer for loading the
    address of objects.  For each indirected object, rather than calculate a
    pointer directly we load a capability from a table.  The runtime
    populates this table.  To populate the table we create a CAPINIT
    relocation for each entry.  The linker requires a size for every symbol
    that we create a CAPINIT relocation for.
    
    This patch adds a `.size` directive to all constants with a DECL by
    implementing the `TARGET_ASM_DECLARE_CONSTANT_NAME` target hook.
    It adds a `.size` directive to every CONSTANT_POOL_ADDRESS_P symbol by
    adding the relevant code to `output_constant_pool_1`.  It adds a `.size`
    directive to the .LTRAMP0 symbol in `assemble_trampoline_template`.
    
    There is still more work to do in this area -- there are more instances
    of this linker complaint in the testsuite -- but these are only for
    symbols that have an explicit size of zero.  Such symbols are currently
    given the bounds of the entire section, and investigation into any
    alternative is a task for the future.
    
    This commit also adds a `.type` directive on each such object since we
    are adding the `.size` directive and specifying that these things are
    objects seems a nice add-on.
    
    We also introduce a helper function that emits the `.type` and `.size`
    directives for an object given its size.
    
    This patch removes a lot of link errors in the testsuite after the
    introduction of the indirection table containing `.capinit` relocations
    for any symbol that is loaded in code.

Diff:
---
 gcc/config/aarch64/aarch64.c | 12 ++++++++++++
 gcc/output.h                 |  5 +++++
 gcc/varasm.c                 | 17 ++++++++++++++++-
 3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 6f34ee8c672..53b479e8c9d 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -11636,6 +11636,15 @@ aarch64_use_anchors_for_symbol_p (const_rtx x)
   return default_use_anchors_for_symbol_p (x);
 }
 
+static void
+aarch64_declare_constant_name (FILE *file, const char *name,
+			       const_tree exp ATTRIBUTE_UNUSED,
+			       HOST_WIDE_INT size)
+{
+  assemble_object_type_and_size (file, name, size);
+  return default_asm_declare_constant_name (file, name, exp, size);
+}
+
 /* Select appropriate section for constants depending
    on where we place literal pools.  */
 
@@ -24814,6 +24823,9 @@ aarch64_libgcc_floating_mode_supported_p
 #undef TARGET_CAPABILITY_MODE
 #define TARGET_CAPABILITY_MODE aarch64_target_capability_mode
 
+#undef TARGET_ASM_DECLARE_CONSTANT_NAME
+#define TARGET_ASM_DECLARE_CONSTANT_NAME aarch64_declare_constant_name
+
 struct gcc_target targetm = TARGET_INITIALIZER;
 
 #include "gt-aarch64.h"
diff --git a/gcc/output.h b/gcc/output.h
index 378fd196b2f..8705aeb2981 100644
--- a/gcc/output.h
+++ b/gcc/output.h
@@ -231,6 +231,11 @@ extern void assemble_external_libcall (rtx);
 /* Assemble a label named NAME.  */
 extern void assemble_label (FILE *, const char *);
 
+/* Assemble the type and size directives associated with a label.
+   Assume that the label is an object (since all use cases at the moment are
+   for objects.  */
+extern void assemble_object_type_and_size (FILE *, const char *, HOST_WIDE_INT);
+
 /* Output to FILE (an assembly file) a reference to NAME.  If NAME
    starts with a *, the rest of NAME is output verbatim.  Otherwise
    NAME is transformed in a target-specific way (usually by the
diff --git a/gcc/varasm.c b/gcc/varasm.c
index d5f41d5ec25..c3c0d1959a5 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -2514,6 +2514,15 @@ assemble_label (FILE *file, const char *name)
   ASM_OUTPUT_LABEL (file, name);
 }
 
+void
+assemble_object_type_and_size (FILE *file, const char *in_name,
+			       HOST_WIDE_INT size)
+{
+  const char *name = targetm.strip_name_encoding (in_name);
+  asm_fprintf (file, "\t.type\t%s, %%object\n", name);
+  asm_fprintf (file, "\t.size\t%s, %" PRId64 "\n", name, size);
+}
+
 /* Set the symbol_referenced flag for ID.  */
 void
 mark_referenced (tree id)
@@ -2681,6 +2690,9 @@ assemble_trampoline_template (void)
   set_mem_align (initial_trampoline, TRAMPOLINE_ALIGNMENT);
   set_mem_size (initial_trampoline, TRAMPOLINE_SIZE);
 
+  /* Output the relevant size for the trampoline.  */
+  assemble_object_type_and_size (asm_out_file, label, TRAMPOLINE_SIZE);
+
   return initial_trampoline;
 }
 \f
@@ -4105,7 +4117,10 @@ output_constant_pool_1 (class constant_descriptor_rtx *desc,
   assemble_align (align);
 
   /* Output the label.  */
-  targetm.asm_out.internal_label (asm_out_file, "LC", desc->labelno);
+  char buf[42];
+  ASM_GENERATE_INTERNAL_LABEL (buf, "LC", desc->labelno);
+  assemble_object_type_and_size (asm_out_file, buf, GET_MODE_SIZE (desc->mode));
+  ASM_OUTPUT_INTERNAL_LABEL (asm_out_file, buf);
 
   /* Output the data.
      Pass actual alignment value while emitting string constant to asm code