#include "varray.h"
#include "ggc.h"
#include "tree-flow.h"
+#include "tree-pass.h"
/* Rewriting a function into SSA form can create a huge number of SSA_NAMEs,
many of which may be thrown away shortly after their creation if jumps
SSA_NAME_DEF_STMT (t) = stmt;
SSA_NAME_PTR_INFO (t) = NULL;
SSA_NAME_IN_FREE_LIST (t) = 0;
+ SSA_NAME_IS_DEFAULT_DEF (t) = 0;
imm = &(SSA_NAME_IMM_USE_NODE (t));
imm->use = NULL;
imm->prev = imm;
/* Never release the default definition for a symbol. It's a
special SSA name that should always exist once it's created. */
- if (var == gimple_default_def (cfun, SSA_NAME_VAR (var)))
+ if (SSA_NAME_IS_DEFAULT_DEF (var))
return;
/* If VAR has been registered for SSA updating, don't remove it.
SSA_NAME_VAR (ssa_name) = sym;
TREE_TYPE (ssa_name) = TREE_TYPE (sym);
}
+
+/* Return SSA names that are unused to GGC memory. This is used to keep
+ footprint of compiler during interprocedural optimization.
+ As a side effect the SSA_NAME_VERSION number reuse is reduced
+ so this function should not be used too often. */
+static unsigned int
+release_dead_ssa_names (void)
+{
+ tree t, next;
+ int n = 0;
+ referenced_var_iterator rvi;
+
+ /* Current defs point to various dead SSA names that in turn points to dead
+ statements so bunch of dead memory is held from releasing. */
+ FOR_EACH_REFERENCED_VAR (t, rvi)
+ set_current_def (t, NULL);
+ /* Now release the freelist. */
+ for (t = FREE_SSANAMES (cfun); t; t = next)
+ {
+ next = TREE_CHAIN (t);
+ /* Dangling pointers might make GGC to still see dead SSA names, so it is
+ important to unlink the list and avoid GGC from seeing all subsequent
+ SSA names. In longer run we want to have all dangling pointers here
+ removed (since they usually go through dead statements that consume
+ considerable amounts of memory). */
+ TREE_CHAIN (t) = NULL_TREE;
+ n++;
+ }
+ FREE_SSANAMES (cfun) = NULL;
+
+ /* Cgraph edges has been invalidated and point to dead statement. We need to
+ remove them now and will rebuild it before next IPA pass. */
+ cgraph_node_remove_callees (cgraph_node (current_function_decl));
+
+ if (dump_file)
+ fprintf (dump_file, "Released %i names, %.2f%%\n", n, n * 100.0 / num_ssa_names);
+ return 0;
+}
+
+struct tree_opt_pass pass_release_ssa_names =
+{
+ "release_ssa", /* name */
+ NULL, /* gate */
+ release_dead_ssa_names, /* execute */
+ NULL, /* sub */
+ NULL, /* next */
+ 0, /* static_pass_number */
+ 0, /* tv_id */
+ PROP_ssa, /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ 0, /* todo_flags_finish */
+ 0 /* letter */
+};