scratch/comp-static-data 0f63d334b9 3/9: Improve how static Lisp strings are generated.

[Vibhav Pant]

branch: scratch/comp-static-data
commit 0f63d334b9c61fb22e697d12bfd56adc718cdd5b
Author: Vibhav Pant <vibhavp@gmail.com>
Commit: Vibhav Pant <vibhavp@gmail.com>

    Improve how static Lisp strings are generated.
    
    * src/comp.c (emit_lisp_string_constructor_rval): Use
    gcc_jit_context_new_string_literal for Lisp strings that don't contain
    NULL bytes, and when debugging is disabled to avoid a libgccjit bug
    where emitting psuedocode for string literal initializers containing
    format strings can cause it to crash.
    
    (define_init_objs): Define Lisp_Strings that are passed to Fread as
    globals to avoid use-after-scope bugs.
---
 src/comp.c | 69 ++++++++++++++++++++++++++++++++++++--------------------------
 1 file changed, 40 insertions(+), 29 deletions(-)

diff --git a/src/comp.c b/src/comp.c
index 4620fb8ff8..6c6935ea78 100644
--- a/src/comp.c
+++ b/src/comp.c
@@ -2183,18 +2183,35 @@ emit_lisp_string_constructor_rval (Lisp_Object str)
 {
   eassert (STRINGP (str));
 
-  static ptrdiff_t i;
-  ptrdiff_t str_size = SBYTES (str) + 1;
-  gcc_jit_type *arr_type
-    = gcc_jit_context_new_array_type (comp.ctxt, NULL,
-                                     comp.unsigned_char_type,
-                                     str_size);
-  gcc_jit_lvalue *str_data
-    = gcc_jit_context_new_global (comp.ctxt, NULL,
-                                 GCC_JIT_GLOBAL_INTERNAL, arr_type,
-                                 format_string ("str_data_%td",
-                                                i++));
-  gcc_jit_global_set_initializer (str_data, SDATA (str), str_size);
+  gcc_jit_rvalue *str_data;
+
+  /* libgccjit has a bug where creating psuedo-code for a string
+     initializer can SIGSEGV if the string contains any format
+     strings, so we avoid using gcc_jit_context_new_string_literal
+     when debugging options are enabled. Additionally, if the string
+     contains a NULL byte, use a regular char array.  */
+  if (memchr (SDATA (str), '\0', SBYTES (str)) == NULL && !comp.debug)
+    str_data
+      = gcc_jit_context_new_string_literal (comp.ctxt, SSDATA (str));
+  else
+    {
+      static ptrdiff_t i;
+      ptrdiff_t str_size = SBYTES (str) + 1;
+
+      gcc_jit_type *arr_type
+       = gcc_jit_context_new_array_type (comp.ctxt, NULL,
+                                         comp.unsigned_char_type,
+                                         str_size);
+      gcc_jit_lvalue *var
+       = gcc_jit_context_new_global (comp.ctxt, NULL,
+                                     GCC_JIT_GLOBAL_INTERNAL,
+                                     arr_type,
+                                     format_string ("str_data_%td",
+                                                    i++));
+      gcc_jit_global_set_initializer (var, SDATA (str), str_size);
+      str_data = gcc_jit_lvalue_get_address (var, NULL);
+    }
+
   gcc_jit_rvalue *size_bytes
     = STRING_MULTIBYTE (str)
       ? gcc_jit_context_new_rvalue_from_long (comp.ctxt,
@@ -2219,8 +2236,7 @@ emit_lisp_string_constructor_rval (Lisp_Object str)
     size_bytes,
     gcc_jit_context_null (comp.ctxt, comp.interval_ptr_type),
     gcc_jit_context_new_cast (comp.ctxt, NULL,
-                             gcc_jit_lvalue_get_address (str_data,
-                                                         NULL),
+                             str_data,
                              comp.unsigned_char_ptr_type),
   };
   gcc_jit_rvalue *u_s
@@ -3321,8 +3337,6 @@ define_init_objs (void)
                                gcc_jit_lvalue_as_rvalue (
                                  comp.func_relocs));
 
-  ptrdiff_t i = 0;
-
   FOR_EACH_TAIL_SAFE (statics)
     {
       Lisp_Object elt;
@@ -3424,19 +3438,19 @@ define_init_objs (void)
 
          if (BARE_SYMBOL_P (value))
            {
-             gcc_jit_lvalue *auto_str
+             gcc_jit_lvalue *lisp_str
                = emit_lisp_data_var (comp.lisp_string_type,
                                      GCC_JIT_GLOBAL_INTERNAL);
              gcc_jit_rvalue *name_lisp_str
                = emit_lisp_string_constructor_rval (
                  Fsymbol_name (value));
-             gcc_jit_global_set_initializer_rvalue (auto_str,
+             gcc_jit_global_set_initializer_rvalue (lisp_str,
                                                     name_lisp_str);
              gcc_jit_rvalue *sym;
              if (!SYMBOL_INTERNED_IN_INITIAL_OBARRAY_P (value))
                {
                  gcc_jit_rvalue *args = emit_make_lisp_ptr (
-                   gcc_jit_lvalue_get_address (auto_str, NULL),
+                   gcc_jit_lvalue_get_address (lisp_str, NULL),
                    Lisp_String);
                  sym
                    = emit_call (intern_c_string ("make-symbol"),
@@ -3446,7 +3460,7 @@ define_init_objs (void)
                {
                  gcc_jit_rvalue *args[]
                    = { emit_make_lisp_ptr (
-                         gcc_jit_lvalue_get_address (auto_str, NULL),
+                         gcc_jit_lvalue_get_address (lisp_str, NULL),
                          Lisp_String),
                        emit_rvalue_from_lisp_obj (Qnil) };
                  sym
@@ -3457,12 +3471,9 @@ define_init_objs (void)
            }
          else
            {
-             gcc_jit_lvalue *auto_str
-               = gcc_jit_function_new_local (comp.func, NULL,
-                                             comp.lisp_string_type,
-                                             format_string ("str_%"
-                                                            "td",
-                                                            i++));
+             gcc_jit_lvalue *lisp_str
+               = emit_lisp_data_var (comp.lisp_string_type,
+                                     GCC_JIT_GLOBAL_INTERNAL);
              specpdl_ref count = SPECPDL_INDEX ();
              /* See emit_static_object_code.   */
              specbind (intern_c_string ("print-escape-newlines"),
@@ -3476,11 +3487,11 @@ define_init_objs (void)
                = Fprin1_to_string (value, Qnil, Qnil);
              unbind_to (count, Qnil);
 
-             gcc_jit_block_add_assignment (
-               comp.block, NULL, auto_str,
+             gcc_jit_global_set_initializer_rvalue (
+               lisp_str,
                emit_lisp_string_constructor_rval (obj_str));
              gcc_jit_rvalue *str = emit_make_lisp_ptr (
-               gcc_jit_lvalue_get_address (auto_str, NULL),
+               gcc_jit_lvalue_get_address (lisp_str, NULL),
                Lisp_String);
              gcc_jit_rvalue *obj
                = emit_call (intern_c_string ("read"),