[gcc(refs/vendors/ARM/heads/morello)] aarch64: Fix segfault in aarch64_mangle_type

[Matthew Malcomson]

https://gcc.gnu.org/g:8067f214025fd95aaa0fc3af962bb22efede8a67

commit 8067f214025fd95aaa0fc3af962bb22efede8a67
Author: Alex Coplan <alex.coplan@arm.com>
Date:   Thu Feb 3 10:57:40 2022 +0000

    aarch64: Fix segfault in aarch64_mangle_type
    
    For pure-capability Morello with the new varargs PCS, we just use void*
    for __builtin_va_list and don't bother building the va_list_type node in
    the backend.
    
    This was causing a segfault via aarch64_mangle_type as it was calling
    lang_hooks.types_compatible_p on a NULL va_list_type node. We don't want
    special mangling for __builtin_va_list with the new PCS. It is simply
    typedef'd to void * and should be mangled as such.  So this patch just
    guards the special mangling on !TARGET_CAPABILITY_PURE, thereby also
    fixing the segfault.
    
    This patch allows us to compile some C++ code for purecap Morello.

Diff:
---
 gcc/config/aarch64/aarch64.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 52d86e47924..17d17a140b6 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -18319,8 +18319,12 @@ static const char *
 aarch64_mangle_type (const_tree type)
 {
   /* The AArch64 ABI documents say that "__va_list" has to be
-     mangled as if it is in the "std" namespace.  */
-  if (lang_hooks.types_compatible_p (CONST_CAST_TREE (type), va_list_type))
+     mangled as if it is in the "std" namespace.
+
+     Note that for purecap Morello, va_list_type is just void* and is
+     mangled accordingly.  */
+  if (!TARGET_CAPABILITY_PURE
+      && lang_hooks.types_compatible_p (CONST_CAST_TREE (type), va_list_type))
     return "St9__va_list";
 
   /* Half-precision floating point types.  */