According to http://gcc.gnu.org/ml/gcc-patches/2009-11/msg01082.html
on Nov 20, 2009, Alexandre Oliva <aol...@redhat.com> wrote:
> On Nov 19, 2009, Richard Guenther <richard.guent...@gmail.com> wrote:
>> In fact this exchanging of the LHS (or rather invalidating of the
>> SSA name value) should be a helper function that knows
>> the implementation details and avoids going through releasing
>> and allocating the name.
> Okie dokie, here's a sequence of patches that implements helper
> functions for this sort of stuff.
> The first patch introduces machinery to propagate “dying” DEFs into
> debug stmts, while replacing them with other SSA_NAMEs.
This is already in.
> The second extends it so as to enable the old LHS to be redefined
> e.g. in terms of the new LHS. IIRC this may be useful in some other
> transformations that, in the process of introducing VTA, I changed from
> modifying stmts in place to inserting new stmts and removing others. I
> haven't looked for them yet.
> The third uses this new feature for the case at hand, while avoiding
> computing the reciprocal expression if we know it won't be used.
Updated versions of these follow. Regstrapped on x86_64-linux-gnu and
i686-linux-gnu. Ok to install?
for gcc/ChangeLog
from Alexandre Oliva <aol...@redhat.com>
PR tree-optimization/42078
* gimple.h (gimple_replace_lhs_wants_value): New.
(gimple_replace_lhs): Add value.
* gimple.c (gimple_replace_lhs): Likewise. Pass it on.
* tree-flow.h (insert_debug_temp_for_var_def): Add value.
* tree-ssa.c (insert_debug_temp_for_var_def): Likewise. Use it.
(insert_debug_temps_for_defs): Pass NULL value.
* tree-ssanames.c (release_ssa_name): Likewise.
* tree-ssa-math-opts.c (execute_cse_reciprocals): Likewise.
* gcc/tree-ssa-reassoc.c (repropagate_negates): Likewise.
Index: gcc/gimple.h
===================================================================
--- gcc/gimple.h.orig 2011-06-02 23:26:12.564872257 -0300
+++ gcc/gimple.h 2011-06-03 01:28:09.413126700 -0300
@@ -886,7 +886,7 @@ void gimple_assign_set_rhs_with_ops_1 (g
tree, tree, tree);
tree gimple_get_lhs (const_gimple);
void gimple_set_lhs (gimple, tree);
-void gimple_replace_lhs (gimple, tree);
+void gimple_replace_lhs (gimple, tree, tree);
gimple gimple_copy (gimple);
void gimple_set_modified (gimple, bool);
void gimple_cond_get_ops_from_tree (tree, enum tree_code *, tree *, tree *);
@@ -2451,6 +2451,14 @@ gimple_has_lhs (gimple stmt)
&& gimple_call_lhs (stmt) != NULL_TREE));
}
+/* Return true if it might be useful to pass a VALUE to
+ gimple_replace_lhs (). */
+static inline bool
+gimple_replace_lhs_wants_value (void)
+{
+ return MAY_HAVE_DEBUG_STMTS;
+}
+
/* Return the code of the predicate computed by conditional statement GS. */
Index: gcc/gimple.c
===================================================================
--- gcc/gimple.c.orig 2011-06-02 23:26:12.562872251 -0300
+++ gcc/gimple.c 2011-06-03 01:28:09.534126597 -0300
@@ -2133,10 +2133,10 @@ gimple_set_lhs (gimple stmt, tree lhs)
expression with a different value.
This will update any annotations (say debug bind stmts) referring
- to the original LHS, so that they use the RHS instead. This is
- done even if NLHS and LHS are the same, for it is understood that
- the RHS will be modified afterwards, and NLHS will not be assigned
- an equivalent value.
+ to the original LHS, so that they use VALUE or the RHS instead.
+ This is done even if NLHS and LHS are the same, for it is
+ understood that the RHS will be modified afterwards, and NLHS will
+ not be assigned an equivalent value.
Adjusting any non-annotation uses of the LHS, if needed, is a
responsibility of the caller.
@@ -2148,15 +2148,20 @@ gimple_set_lhs (gimple stmt, tree lhs)
copying and removing. */
void
-gimple_replace_lhs (gimple stmt, tree nlhs)
+gimple_replace_lhs (gimple stmt, tree nlhs, tree value)
{
+ /* If the conditions in which this function uses VALUE change,
+ adjust gimple_replace_lhs_wants_value(). */
+ gcc_assert (gimple_replace_lhs_wants_value ()
+ == MAY_HAVE_DEBUG_STMTS);
+
if (MAY_HAVE_DEBUG_STMTS)
{
tree lhs = gimple_get_lhs (stmt);
gcc_assert (SSA_NAME_DEF_STMT (lhs) == stmt);
- insert_debug_temp_for_var_def (NULL, lhs);
+ insert_debug_temp_for_var_def (NULL, lhs, value);
}
gimple_set_lhs (stmt, nlhs);
Index: gcc/tree-flow.h
===================================================================
--- gcc/tree-flow.h.orig 2011-06-02 23:26:53.941986549 -0300
+++ gcc/tree-flow.h 2011-06-03 01:28:55.486087124 -0300
@@ -553,7 +553,7 @@ typedef bool (*walk_use_def_chains_fn) (
extern void walk_use_def_chains (tree, walk_use_def_chains_fn, void *, bool);
void insert_debug_temps_for_defs (gimple_stmt_iterator *);
-void insert_debug_temp_for_var_def (gimple_stmt_iterator *, tree);
+void insert_debug_temp_for_var_def (gimple_stmt_iterator *, tree, tree);
void reset_debug_uses (gimple);
void release_defs_bitset (bitmap toremove);
Index: gcc/tree-ssa.c
===================================================================
--- gcc/tree-ssa.c.orig 2011-06-02 23:26:54.156987140 -0300
+++ gcc/tree-ssa.c 2011-06-03 01:28:09.611126531 -0300
@@ -294,17 +294,25 @@ find_released_ssa_name (tree *tp, int *w
/* Insert a DEBUG BIND stmt before the DEF of VAR if VAR is referenced
by other DEBUG stmts, and replace uses of the DEF with the
- newly-created debug temp. */
+ newly-created debug temp, or with the DEF's value, if the
+ substitution is valid. The value is taken from VALUE, if given, or
+ from the DEF stmt, taken from GSI, if given, or from the DEF of
+ VAR. If VALUE and VAR are the same, no DEBUG BIND stmt will be
+ created, and all uses of VAR will be reset. If a DEBUG BIND stmt
+ has to be created, it will be inserted before or after GSI or the
+ DEF, depending */
void
-insert_debug_temp_for_var_def (gimple_stmt_iterator *gsi, tree var)
+insert_debug_temp_for_var_def (gimple_stmt_iterator *gsi, tree var, tree value)
{
imm_use_iterator imm_iter;
use_operand_p use_p;
gimple stmt;
gimple def_stmt = NULL;
int usecount = 0;
- tree value = NULL;
+ bool given_value;
+ gimple def_temp = NULL;
+ gimple_stmt_iterator ngsi;
if (!MAY_HAVE_DEBUG_STMTS)
return;
@@ -344,10 +352,13 @@ insert_debug_temp_for_var_def (gimple_st
else
def_stmt = SSA_NAME_DEF_STMT (var);
+ given_value = false;
+ if (value)
+ given_value = true;
/* If we didn't get an insertion point, and the stmt has already
been removed, we won't be able to insert the debug bind stmt, so
we'll have to drop debug information. */
- if (gimple_code (def_stmt) == GIMPLE_PHI)
+ else if (gimple_code (def_stmt) == GIMPLE_PHI)
{
value = degenerate_phi_result (def_stmt);
if (value && walk_tree (&value, find_released_ssa_name, NULL, NULL))
@@ -402,6 +413,9 @@ insert_debug_temp_for_var_def (gimple_st
value = gimple_assign_rhs_to_tree (def_stmt);
}
+ if (value == var)
+ value = NULL;
+
if (value)
{
/* If there's a single use of VAR, and VAR is the entire debug
@@ -419,7 +433,7 @@ insert_debug_temp_for_var_def (gimple_st
at the expense of duplication of expressions. */
if (CONSTANT_CLASS_P (value)
- || gimple_code (def_stmt) == GIMPLE_PHI
+ || (gimple_code (def_stmt) == GIMPLE_PHI && !given_value)
|| (usecount == 1
&& (!gimple_assign_single_p (def_stmt)
|| is_gimple_min_invariant (value)))
@@ -427,7 +441,6 @@ insert_debug_temp_for_var_def (gimple_st
value = unshare_expr (value);
else
{
- gimple def_temp;
tree vexpr = make_node (DEBUG_EXPR_DECL);
def_temp = gimple_build_debug_bind (vexpr,
@@ -441,14 +454,27 @@ insert_debug_temp_for_var_def (gimple_st
else
DECL_MODE (vexpr) = TYPE_MODE (TREE_TYPE (value));
- if (gsi)
- gsi_insert_before (gsi, def_temp, GSI_SAME_STMT);
- else
+ if (gimple_code (def_stmt) == GIMPLE_PHI)
+ {
+ basic_block bb;
+
+ if (gsi)
+ bb = gsi_bb (*gsi);
+ else
+ bb = gimple_bb (def_stmt);
+
+ ngsi = gsi_after_labels (bb);
+ gsi = &ngsi;
+ }
+ else if (!gsi)
{
- gimple_stmt_iterator ngsi = gsi_for_stmt (def_stmt);
- gsi_insert_before (&ngsi, def_temp, GSI_SAME_STMT);
+ ngsi = gsi_for_stmt (def_stmt);
+ gsi = &ngsi;
}
+ if (!given_value)
+ gsi_insert_before (gsi, def_temp, GSI_SAME_STMT);
+
value = vexpr;
}
}
@@ -477,6 +503,11 @@ insert_debug_temp_for_var_def (gimple_st
update_stmt (stmt);
}
+
+ /* Insert the definition last, so that we don't modify it in case
+ VALUE references VAR. Assume the caller intends it to be so. */
+ if (def_temp && given_value)
+ gsi_insert_after (gsi, def_temp, GSI_SAME_STMT);
}
@@ -503,7 +534,7 @@ insert_debug_temps_for_defs (gimple_stmt
if (TREE_CODE (var) != SSA_NAME)
continue;
- insert_debug_temp_for_var_def (gsi, var);
+ insert_debug_temp_for_var_def (gsi, var, NULL);
}
}
Index: gcc/tree-ssanames.c
===================================================================
--- gcc/tree-ssanames.c.orig 2011-06-02 23:26:54.157987143 -0300
+++ gcc/tree-ssanames.c 2011-06-03 01:28:09.623126522 -0300
@@ -203,7 +203,7 @@ release_ssa_name (tree var)
use_operand_p imm = &(SSA_NAME_IMM_USE_NODE (var));
if (MAY_HAVE_DEBUG_STMTS)
- insert_debug_temp_for_var_def (NULL, var);
+ insert_debug_temp_for_var_def (NULL, var, NULL);
#ifdef ENABLE_CHECKING
verify_imm_links (stderr, var);
Index: gcc/tree-ssa-math-opts.c
===================================================================
--- gcc/tree-ssa-math-opts.c.orig 2011-06-02 23:26:54.149987121 -0300
+++ gcc/tree-ssa-math-opts.c 2011-06-03 01:28:09.658126490 -0300
@@ -603,7 +603,7 @@ execute_cse_reciprocals (void)
if (fail)
continue;
- gimple_replace_lhs (stmt1, arg1);
+ gimple_replace_lhs (stmt1, arg1, NULL);
gimple_call_set_fndecl (stmt1, fndecl);
update_stmt (stmt1);
reciprocal_stats.rfuncs_inserted++;
Index: gcc/tree-ssa-reassoc.c
===================================================================
--- gcc/tree-ssa-reassoc.c.orig 2011-06-02 23:26:54.152987130 -0300
+++ gcc/tree-ssa-reassoc.c 2011-06-03 01:28:09.684126469 -0300
@@ -1935,7 +1935,7 @@ repropagate_negates (void)
tree a = gimple_assign_rhs1 (feed);
tree rhs2 = gimple_assign_rhs2 (user);
gimple_stmt_iterator gsi = gsi_for_stmt (feed), gsi2;
- gimple_replace_lhs (feed, negate);
+ gimple_replace_lhs (feed, negate, NULL);
gimple_assign_set_rhs_with_ops (&gsi, PLUS_EXPR, a, rhs2);
update_stmt (gsi_stmt (gsi));
gsi2 = gsi_for_stmt (user);
for gcc/ChangeLog
from Alexandre Oliva <aol...@redhat.com>
PR tree-optimization/42078
* tree-ssa-math-opts.c (execute_cse_reciprocals): Compute reciprocal
value for debug stmts.
Index: gcc/tree-ssa-math-opts.c
===================================================================
--- gcc/tree-ssa-math-opts.c.orig 2011-06-03 01:29:09.427075107 -0300
+++ gcc/tree-ssa-math-opts.c 2011-06-03 01:30:25.688009048 -0300
@@ -574,6 +574,7 @@ execute_cse_reciprocals (void)
bool md_code, fail;
imm_use_iterator ui;
use_operand_p use_p;
+ tree value;
code = DECL_FUNCTION_CODE (fndecl);
md_code = DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_MD;
@@ -603,13 +604,24 @@ execute_cse_reciprocals (void)
if (fail)
continue;
- gimple_replace_lhs (stmt1, arg1, NULL);
+ if (gimple_replace_lhs_wants_value ())
+ {
+ tree t = TREE_TYPE (arg1);
+
+ value = build2 (RDIV_EXPR, t, build_one_cst (t), arg1);
+ }
+ else
+ value = NULL;
+
+ gimple_replace_lhs (stmt1, arg1, value);
gimple_call_set_fndecl (stmt1, fndecl);
update_stmt (stmt1);
reciprocal_stats.rfuncs_inserted++;
FOR_EACH_IMM_USE_STMT (stmt, ui, arg1)
{
+ if (is_gimple_debug (stmt))
+ continue;
gimple_assign_set_rhs_code (stmt, MULT_EXPR);
fold_stmt_inplace (stmt);
update_stmt (stmt);
--
Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/ FSF Latin America board member
Free Software Evangelist Red Hat Brazil Compiler Engineer
