[gcc r12-2969] Darwin: Reset section names table at the end of compile.

[gcc r12-2969] Darwin: Reset section names table at the end of compile.

[Iain D Sandoe]

https://gcc.gnu.org/g:2d9da1c89778be1d6604cc1465b0dd50f241a352

commit r12-2969-g2d9da1c89778be1d6604cc1465b0dd50f241a352
Author: Iain Sandoe <iain@sandoe.co.uk>
Date:   Fri Aug 13 20:20:04 2021 +0100

    Darwin: Reset section names table at the end of compile.
    
    For a single use (typical compile) this vector will be reclaimed
    as GGC.  For JIT this is not sufficient since it does not reset
    the pointer to NULL (and thus we think the the vector is already
    allocated when a context is reused).
    
    The clears the vector and sets the pointer to NULL at the end
    of object output.
    
    Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
    
    gcc/ChangeLog:
    
            * config/darwin.c (darwin_file_end): Reset and reclaim the
            section names table at the end of compile.

Diff:
---
 gcc/config/darwin.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/gcc/config/darwin.c b/gcc/config/darwin.c
index b160c23ea56..5d1d13c80aa 100644
--- a/gcc/config/darwin.c
+++ b/gcc/config/darwin.c
@@ -3129,6 +3129,14 @@ darwin_file_end (void)
      re-arranging data.  */
   if (!DARWIN_SECTION_ANCHORS || !flag_section_anchors)
     fprintf (asm_out_file, "\t.subsections_via_symbols\n");
+
+  /* We rely on this being NULL at the start of compilation; reset it here
+     so that JIT can reuse a context.  */
+  if (dwarf_sect_names_table != NULL)
+    {
+      dwarf_sect_names_table->truncate (0);
+      dwarf_sect_names_table = NULL;
+    }
 }
 
 /* TODO: Add a language hook for identifying if a decl is a vtable.  */