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tree-ssa-live.c: Include debug.h and flags.h.

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* tree-ssa-live.c: Include debug.h and flags.h.
	(mark_scope_block_unused): New function.
	(remove_unused_scope_block_p): New function.
	(remove_unused_locals): Remove unused blocks too.

From-SVN: r126947
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Jan Hubicka 2007-07-26 05:43:40 +02:00 committed by Jan Hubicka
parent e13642b658
commit aee46bbdf8
2 changed files with 121 additions and 1 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2007-07-26 Jan Hubicka <jh@suse.cz>
* tree-ssa-live.c: Include debug.h and flags.h.
(mark_scope_block_unused): New function.
(remove_unused_scope_block_p): New function.
(remove_unused_locals): Remove unused blocks too.
2007-07-25 Ian Lance Taylor <iant@google.com>
* combine.c (combine_max_regno): Remove. Remove all uses.

115
gcc/tree-ssa-live.c
View File

@ -30,6 +30,8 @@ Boston, MA 02110-1301, USA. */
#include "tree-dump.h"
#include "tree-ssa-live.h"
#include "toplev.h"
#include "debug.h"
#include "flags.h"
#ifdef ENABLE_CHECKING
static void verify_live_on_entry (tree_live_info_p);
@ -405,9 +407,15 @@ mark_all_vars_used_1 (tree *tp, int *walk_subtrees,
void *data ATTRIBUTE_UNUSED)
{
tree t = *tp;
enum tree_code_class c = TREE_CODE_CLASS (TREE_CODE (t));
tree b;
if (TREE_CODE (t) == SSA_NAME)
t = SSA_NAME_VAR (t);
if ((IS_EXPR_CODE_CLASS (c)
|| IS_GIMPLE_STMT_CODE_CLASS (c))
&& (b = TREE_BLOCK (t)) != NULL)
TREE_USED (b) = true;
/* Ignore TREE_ORIGINAL for TARGET_MEM_REFS, as well as other
fields that do not contain vars. */
@ -431,6 +439,110 @@ mark_all_vars_used_1 (tree *tp, int *walk_subtrees,
return NULL;
}
/* Mark the scope block SCOPE and its subblocks unused when they can be
possibly eliminated if dead. */
static void
mark_scope_block_unused (tree scope)
{
tree t;
TREE_USED (scope) = false;
if (!(*debug_hooks->ignore_block) (scope))
TREE_USED (scope) = true;
for (t = BLOCK_SUBBLOCKS (scope); t ; t = BLOCK_CHAIN (t))
mark_scope_block_unused (t);
}
/* Look if the block is dead (by possibly eliminating its dead subblocks)
and return true if so.
Block is declared dead if:
1) No statements are associated with it.
2) Declares no live variables
3) All subblocks are dead
or there is precisely one subblocks and the block
has same abstract origin as outer block and declares
no variables, so it is pure wrapper.
When we are not outputting full debug info, we also elliminate dead variables
out of scope blocks to let them to be recycled by GGC and to save copying work
done by the inliner. */
static bool
remove_unused_scope_block_p (tree scope)
{
tree *t, *next;
bool unused = !TREE_USED (scope);
var_ann_t ann;
int nsubblocks = 0;
for (t = &BLOCK_VARS (scope); *t; t = next)
{
next = &TREE_CHAIN (*t);
/* Debug info of nested function reffers to the block of the
function. */
if (TREE_CODE (*t) == FUNCTION_DECL)
unused = false;
/* When we are outputting debug info, we usually want to output
info about optimized-out variables in the scope blocks.
Exception are the scope blocks not containing any instructions
at all so user can't get into the scopes at first place. */
else if ((ann = var_ann (*t)) != NULL
&& ann->used)
unused = false;
/* When we are not doing full debug info, we however can keep around
only the used variables for cfgexpand's memory packing saving quite
a lot of memory. */
else if (debug_info_level != DINFO_LEVEL_NORMAL
&& debug_info_level != DINFO_LEVEL_VERBOSE)
{
*t = TREE_CHAIN (*t);
next = t;
}
}
for (t = &BLOCK_SUBBLOCKS (scope); *t ;)
if (remove_unused_scope_block_p (*t))
{
if (BLOCK_SUBBLOCKS (*t))
{
tree next = BLOCK_CHAIN (*t);
tree supercontext = BLOCK_SUPERCONTEXT (*t);
*t = BLOCK_SUBBLOCKS (*t);
gcc_assert (!BLOCK_CHAIN (*t));
BLOCK_CHAIN (*t) = next;
BLOCK_SUPERCONTEXT (*t) = supercontext;
t = &BLOCK_CHAIN (*t);
nsubblocks ++;
}
else
*t = BLOCK_CHAIN (*t);
}
else
{
t = &BLOCK_CHAIN (*t);
nsubblocks ++;
}
/* Outer scope is always used. */
if (!BLOCK_SUPERCONTEXT (scope)
|| TREE_CODE (BLOCK_SUPERCONTEXT (scope)) == FUNCTION_DECL)
unused = false;
/* If there are more than one live subblocks, it is used. */
else if (nsubblocks > 1)
unused = false;
/* When there is only one subblock, see if it is just wrapper we can
ignore. Wrappers are not declaring any variables and not changing
abstract origin. */
else if (nsubblocks == 1
&& (BLOCK_VARS (scope)
|| ((debug_info_level == DINFO_LEVEL_NORMAL
|| debug_info_level == DINFO_LEVEL_VERBOSE)
&& ((BLOCK_ABSTRACT_ORIGIN (scope)
!= BLOCK_ABSTRACT_ORIGIN (BLOCK_SUPERCONTEXT (scope)))))))
unused = false;
return unused;
}
/* Mark all VAR_DECLS under *EXPR_P as used, so that they won't be
eliminated during the tree->rtl conversion process. */
@ -452,6 +564,7 @@ remove_unused_locals (void)
referenced_var_iterator rvi;
var_ann_t ann;
mark_scope_block_unused (DECL_INITIAL (current_function_decl));
/* Assume all locals are unused. */
FOR_EACH_REFERENCED_VAR (t, rvi)
var_ann (t)->used = false;
@ -498,7 +611,6 @@ remove_unused_locals (void)
*cell = TREE_CHAIN (*cell);
continue;
}
cell = &TREE_CHAIN (*cell);
}
@ -516,6 +628,7 @@ remove_unused_locals (void)
&& !ann->symbol_mem_tag
&& !TREE_ADDRESSABLE (t))
remove_referenced_var (t);
remove_unused_scope_block_p (DECL_INITIAL (current_function_decl));
}