[M3devel] m3cc static chain stuff
Jay K
jay.krell at cornell.edu
Wed May 26 08:05:25 CEST 2010
Can any of this be removed?
Can we really not just use "unfold-nested-procs" like NT386?
We'd just lose a little bit of optimization, in rare cases, stop paying a bad cost/benefit ratio?
Part of this is actually *deoptimization*. If the compiler decides the values aren't used, then it should
be allowed to remove them. That is normal. Wanting to unused stuff in the debugger isn't
generally a considered the responsibility of optimizers.
Therefore -- we could "unfold", remove our diffs, and gain some optimization and some deoptimization.
Maybe I'll try without.
diff -ur /src/orig/gcc-4.3.0/gcc/tree-nested.c /dev2/cm3/m3-sys/m3cc/gcc/gcc/tree-nested.c
--- /src/orig/gcc-4.3.0/gcc/tree-nested.c 2008-02-15 09:36:43.000000000 -0800
+++ /dev2/cm3/m3-sys/m3cc/gcc/gcc/tree-nested.c 2010-05-09 22:27:58.000000000 -0700
-/* Build or return the RECORD_TYPE that describes the frame state that is
- shared between INFO->CONTEXT and its nested functions. This record will
- not be complete until finalize_nesting_tree; up until that point we'll
+/* This must agree with the string defined by the same name in m3gdb, file
+ m3-util.c */
+static const char * nonlocal_var_rec_name = "_nonlocal_var_rec";
+
+/* Build or return the RECORD_TYPE that describes the non-local frame struct
+ that is shared between INFO->CONTEXT and its nested functions. This record
+ will not be complete until finalize_nesting_tree; up until that point we'll
be adding fields as necessary.
We also build the DECL that represents this frame in the function. */
@@ -209,7 +224,8 @@
free (name);
info->frame_type = type;
- info->frame_decl = create_tmp_var_for (info, type, "FRAME");
+ info->frame_decl
+ = create_tmp_var_for (info, type, nonlocal_var_rec_name);
/* ??? Always make it addressable for now, since it is meant to
be pointed to by the static chain pointer. This pessimizes
@@ -218,6 +234,8 @@
reachable, but the true pessimization is to create the non-
local frame structure in the first place. */
TREE_ADDRESSABLE (info->frame_decl) = 1;
+ /* m3gdb needs to know about this variable. */
+ DECL_IGNORED_P (info->frame_decl) = 0;
}
return type;
}
@@ -290,6 +308,10 @@
return *slot;
}
+/* This must agree with the string defined by the same name in m3gdb, file
+ m3_util.c */
+static const char * static_link_var_name = "_static_link_var";
+
/* Build or return the variable that holds the static chain within
INFO->CONTEXT. This variable may only be used within INFO->CONTEXT. */
@@ -310,9 +332,14 @@
Note also that it's represented as a parameter. This is more
close to the truth, since the initial value does come from
the caller. */
- decl = build_decl (PARM_DECL, create_tmp_var_name ("CHAIN"), type);
+ decl = build_decl
+ (PARM_DECL, get_identifier (static_link_var_name), type);
+ TREE_CHAIN (decl) = NULL; /* Possibly redundant, but dbxout needs it. */
DECL_ARTIFICIAL (decl) = 1;
- DECL_IGNORED_P (decl) = 1;
+
+ /* m3gdb needs to know about this variable. */
+ DECL_IGNORED_P (decl) = 0;
+
TREE_USED (decl) = 1;
DECL_CONTEXT (decl) = info->context;
DECL_ARG_TYPE (decl) = type;
@@ -326,7 +353,11 @@
return decl;
}
-/* Build or return the field within the non-local frame state that holds
+/* This must agree with the string defined by the same name in m3gdb, file
+ m3_util.c */
+static const char * static_link_copy_field_name = "_static_link_copy_field";
+
+/* Build or return the field within the non-local frame struct that holds
the static chain for INFO->CONTEXT. This is the way to walk back up
multiple nesting levels. */
@@ -339,10 +370,12 @@
tree type = build_pointer_type (get_frame_type (info->outer));
field = make_node (FIELD_DECL);
- DECL_NAME (field) = get_identifier ("__chain");
+ DECL_NAME (field) = get_identifier (static_link_copy_field_name);
TREE_TYPE (field) = type;
DECL_ALIGN (field) = TYPE_ALIGN (type);
DECL_NONADDRESSABLE_P (field) = 1;
+ /* m3gdb should know about this field. */
+ DECL_IGNORED_P (field) = 0;
insert_field_into_struct (get_frame_type (info), field);
@@ -465,7 +498,7 @@
return *slot;
}
-/* Build or return the field within the non-local frame state that holds
+/* Build or return the field within the non-local frame struct that holds
the non-local goto "jmp_buf". The buffer itself is maintained by the
rtl middle-end as dynamic stack space is allocated. */
@@ -1620,6 +1653,9 @@
switch (TREE_CODE (t))
{
case ADDR_EXPR:
+ if (TREE_STATIC (t))
+ break;
+
/* Build
T.1 = &CHAIN->tramp;
T.2 = __builtin_adjust_trampoline (T.1);
@@ -1714,6 +1750,22 @@
}
break;
+ case STATIC_CHAIN_EXPR:
+ decl = TREE_OPERAND (t, 0);
+ target_context = decl_function_context (decl);
+ if (target_context)
+ {
+ if (info->context == target_context)
+ {
+ /* Make sure frame_decl gets created. */
+ (void) get_frame_type (info);
+ }
+ *tp = get_static_chain (info, target_context, &wi->tsi);
+ }
+ else
+ *tp = null_pointer_node;
+ break;
+
case RETURN_EXPR:
case GIMPLE_MODIFY_STMT:
case WITH_SIZE_EXPR:
@@ -1768,13 +1820,22 @@
return NULL_TREE;
}
+static bool
+debug_static_links (void)
+{ return
+ write_symbols != NO_DEBUG
+ && debug_info_level != DINFO_LEVEL_NONE
+ && debug_info_level != DINFO_LEVEL_TERSE;
+
+} /* debug_static_links */
+
/* Walk the nesting tree starting with ROOT, depth first. Convert all
trampolines and call expressions. On the way back up, determine if
a nested function actually uses its static chain; if not, remember that. */
static void
convert_all_function_calls (struct nesting_info *root)
-{
+{
do
{
if (root->inner)
@@ -1784,7 +1845,10 @@
walk_function (convert_call_expr, root);
/* If the function does not use a static chain, then remember that. */
- if (root->outer && !root->chain_decl && !root->chain_field)
+ if (root->outer && !root->chain_decl && !root->chain_field
+/* REMOVE ME: */
+ /* && !debug_static_links () */
+ )
DECL_NO_STATIC_CHAIN (root->context) = 1;
else
gcc_assert (!DECL_NO_STATIC_CHAIN (root->context));
@@ -1806,6 +1870,21 @@
tree context = root->context;
struct function *sf;
+/* REMOVEME: */
+ /* If this is a nested function and we are supporting debugging via
+ m3gdb, we always need a chain_decl, so m3gdb can find the static
+ chain, even if the programmer's code doesn't use it. */
+ if (false && root->outer && debug_static_links () )
+ { tree static_chain_decl, temp, stmt;
+ /* This is a desperate attempt to get later code generation to
+ store the static link. If it works, it'll be a miracle. */
+ static_chain_decl = get_chain_decl (root);
+ stmt = build_addr (static_chain_decl, root->context);
+ temp = create_tmp_var_for (root, TREE_TYPE (static_chain_decl), NULL);
+ stmt = build_gimple_modify_stmt (temp, static_chain_decl);
+ append_to_statement_list (stmt, &stmt_list);
+ }
+
/* If we created a non-local frame type or decl, we need to lay them
out at this time. */
if (root->frame_type)
@@ -1912,7 +1991,7 @@
proper BIND_EXPR. */
if (root->new_local_var_chain)
declare_vars (root->new_local_var_chain, DECL_SAVED_TREE (root->context),
- false);
+ true);
if (root->debug_var_chain)
declare_vars (root->debug_var_chain, DECL_SAVED_TREE (root->context),
true);
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