[gcc r14-7040] aarch64: Fix up GC of aarch64_simd_types [PR113270]

[Jakub Jelinek]

https://gcc.gnu.org/g:33b1173361b08919ef9011e335072925d38327df

commit r14-7040-g33b1173361b08919ef9011e335072925d38327df
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue Jan 9 13:57:23 2024 +0100

    aarch64: Fix up GC of aarch64_simd_types [PR113270]
    
    The r14-6524 changes created aarch64-builtins.h header and moved
    struct aarch64_simd_type_info definition in there.
    Unfortunately, the new header wasn't added to target_gtfiles, so the
    trees and const char * pointer elements in the aarch64_simd_types
    array aren't marked as GC roots anymore.  That breaks e.g. PCH, when
    the array elements then can refer to ggc_freed memory instead of the expected
    types, but also any other GC collection could free them and further uses would
    not work correctly.
    
    Unfortunately, just adding the new header to target_gtfiles doesn't fix this,
    because non-static variable definitions marked with GTY(()) aren't considered
    by gengtype, it looks in those cases for an extern GTY(()) declaration, and
    there was none - the aarch64-builtins.h header contains an extern declaration
    without GTY(()).  Adding GTY(()) to that extern declaration doesn't work, because
    then gengtype attempts to emit the aarch64_simd_types GC roots in gtype-desc.cc
    but the corresponding header isn't included there.
    
    So, the patch instead adds another extern declaration in aarch64-builtins.cc
    right before the actual definition, which makes sure the GC roots are registered
    correctly in gt-aarch64-builtins.h (where we want them).
    
    2024-01-09  Jakub Jelinek  <jakub@redhat.com>
    
            PR target/113270
            * config.gcc (aarch64*-*-*): Add aarch64-builtins.h to target_gtfiles.
            * config/aarch64/aarch64-builtins.cc (aarch64_simd_types): Add extern
            GTY(()) declaration before the definition, drop GTY(()) drom the
            definition.

Diff:
---
 gcc/config.gcc                         | 2 +-
 gcc/config/aarch64/aarch64-builtins.cc | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/gcc/config.gcc b/gcc/config.gcc
index 7e583390024..d17787bc9ad 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -350,7 +350,7 @@ aarch64*-*-*)
 	cxx_target_objs="aarch64-c.o"
 	d_target_objs="aarch64-d.o"
 	extra_objs="aarch64-builtins.o aarch-common.o aarch64-sve-builtins.o aarch64-sve-builtins-shapes.o aarch64-sve-builtins-base.o aarch64-sve-builtins-sve2.o aarch64-sve-builtins-sme.o cortex-a57-fma-steering.o aarch64-speculation.o falkor-tag-collision-avoidance.o aarch-bti-insert.o aarch64-cc-fusion.o aarch64-early-ra.o aarch64-ldp-fusion.o"
-	target_gtfiles="\$(srcdir)/config/aarch64/aarch64-builtins.cc \$(srcdir)/config/aarch64/aarch64-sve-builtins.h \$(srcdir)/config/aarch64/aarch64-sve-builtins.cc"
+	target_gtfiles="\$(srcdir)/config/aarch64/aarch64-builtins.h \$(srcdir)/config/aarch64/aarch64-builtins.cc \$(srcdir)/config/aarch64/aarch64-sve-builtins.h \$(srcdir)/config/aarch64/aarch64-sve-builtins.cc"
 	target_has_targetm_common=yes
 	;;
 alpha*-*-*)
diff --git a/gcc/config/aarch64/aarch64-builtins.cc b/gcc/config/aarch64/aarch64-builtins.cc
index d78041e0e85..9b23b6b8c33 100644
--- a/gcc/config/aarch64/aarch64-builtins.cc
+++ b/gcc/config/aarch64/aarch64-builtins.cc
@@ -863,9 +863,11 @@ const char *aarch64_scalar_builtin_types[] = {
   NULL
 };
 
+extern GTY(()) aarch64_simd_type_info aarch64_simd_types[];
+
 #define ENTRY(E, M, Q, G)  \
   {E, "__" #E, #G "__" #E, NULL_TREE, NULL_TREE, E_##M##mode, qualifier_##Q},
-GTY(()) struct aarch64_simd_type_info aarch64_simd_types [] = {
+struct aarch64_simd_type_info aarch64_simd_types [] = {
 #include "aarch64-simd-builtin-types.def"
 };
 #undef ENTRY