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[PATCH]: Fix PR tree-optimization/21173
- From: Daniel Berlin <dberlin at dberlin dot org>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Sun, 24 Apr 2005 22:02:34 -0400
- Subject: [PATCH]: Fix PR tree-optimization/21173
Attached are two patches to fix tree-optimization/21173.
We had some bugs combining synergisticly to cause us to screw this one
up. We were accidently losing the - part of a pointer subtraction due
to another bugfix, which was actually pegging the wrong thing as the
problem.
The real underlying cause of all of our troubles from this bug, and
20963, is that force_gimple_operand was modifying the tree we passed to
it, when that tree was shared in various places, and thus, shouldn't
have been touched.
The patch for 4.0 does the minimum necessary to fix the bug, which is to
unshare_expr the tree we pass to force_gimple_operand, and stop trying
to special case min_invariants.
The patch for 4.1, by Steven Bosscher, also has a bit of code
unification and cleanup of the create_expression_by_pieces function in
it.
I've bootstrapped and regtested both of them on i686-pc-linux-gnu, and
will apply each patch to the appropriate place :)
2005-04-24 Daniel Berlin <dberlin@dberlin.org>
Fix PR tree-optimization/21173
* tree-ssa-pre.c (create_expression_by_pieces): Call unshare_expr
on things we pass to force_gimple_operand. Don't try to special
case min_invariants.
Index: tree-ssa-pre.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-ssa-pre.c,v
retrieving revision 2.65.4.2
diff -u -p -r2.65.4.2 tree-ssa-pre.c
--- tree-ssa-pre.c 17 Apr 2005 23:40:31 -0000 2.65.4.2
+++ tree-ssa-pre.c 25 Apr 2005 01:56:41 -0000
@@ -1330,7 +1330,8 @@ create_expression_by_pieces (basic_block
folded = fold (build (TREE_CODE (expr), TREE_TYPE (expr),
genop1, genop2));
- newexpr = force_gimple_operand (folded, &forced_stmts, false, NULL);
+ newexpr = force_gimple_operand (unshare_expr (folded),
+ &forced_stmts, false, NULL);
if (forced_stmts)
{
tsi = tsi_start (forced_stmts);
@@ -1372,14 +1373,8 @@ create_expression_by_pieces (basic_block
add_referenced_tmp_var (temp);
folded = fold (build (TREE_CODE (expr), TREE_TYPE (expr),
genop1));
- /* If the generated operand is already GIMPLE min_invariant
- just use it instead of calling force_gimple_operand on it,
- since that may make it not invariant by copying it into an
- assignment. */
- if (!is_gimple_min_invariant (genop1))
- newexpr = force_gimple_operand (folded, &forced_stmts, false, NULL);
- else
- newexpr = genop1;
+ newexpr = force_gimple_operand (unshare_expr (folded),
+ &forced_stmts, false, NULL);
if (forced_stmts)
{
tsi = tsi_start (forced_stmts);
2005-04-24 Steven Bosscher <stevenb@suse.de>
Fix PR tree-optimization/21173
* tree-ssa-pre.c (create_expression_by_pieces): Simplify code.
Unshare expression we pass to force_gimple_operand.
Index: tree-ssa-pre.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-ssa-pre.c,v
retrieving revision 2.81
diff -u -p -r2.81 tree-ssa-pre.c
--- tree-ssa-pre.c 24 Apr 2005 14:15:12 -0000 2.81
+++ tree-ssa-pre.c 25 Apr 2005 01:55:48 -0000
@@ -1319,126 +1319,94 @@ find_or_generate_expression (basic_block
static tree
create_expression_by_pieces (basic_block block, tree expr, tree stmts)
{
- tree name = NULL_TREE;
- tree newexpr = NULL_TREE;
+ tree temp, name;
+ tree folded, forced_stmts, newexpr;
tree v;
-
+ tree_stmt_iterator tsi;
+
switch (TREE_CODE_CLASS (TREE_CODE (expr)))
{
case tcc_binary:
case tcc_comparison:
{
- tree_stmt_iterator tsi;
- tree forced_stmts;
- tree genop1, genop2;
- tree temp;
- tree folded;
tree op1 = TREE_OPERAND (expr, 0);
tree op2 = TREE_OPERAND (expr, 1);
- genop1 = find_or_generate_expression (block, op1, stmts);
- genop2 = find_or_generate_expression (block, op2, stmts);
- temp = create_tmp_var (TREE_TYPE (expr), "pretmp");
- add_referenced_tmp_var (temp);
-
+ tree genop1 = find_or_generate_expression (block, op1, stmts);
+ tree genop2 = find_or_generate_expression (block, op2, stmts);
folded = fold (build (TREE_CODE (expr), TREE_TYPE (expr),
genop1, genop2));
- newexpr = force_gimple_operand (folded, &forced_stmts, false, NULL);
- if (forced_stmts)
- {
- tsi = tsi_start (forced_stmts);
- for (; !tsi_end_p (tsi); tsi_next (&tsi))
- {
- tree stmt = tsi_stmt (tsi);
- tree forcedname = TREE_OPERAND (stmt, 0);
- tree forcedexpr = TREE_OPERAND (stmt, 1);
- tree val = vn_lookup_or_add (forcedexpr, NULL);
- vn_add (forcedname, val, NULL);
- bitmap_value_replace_in_set (NEW_SETS (block), forcedname);
- bitmap_value_replace_in_set (AVAIL_OUT (block), forcedname);
- }
-
- tsi = tsi_last (stmts);
- tsi_link_after (&tsi, forced_stmts, TSI_CONTINUE_LINKING);
- }
- newexpr = build (MODIFY_EXPR, TREE_TYPE (expr),
- temp, newexpr);
- NECESSARY (newexpr) = 0;
- name = make_ssa_name (temp, newexpr);
- TREE_OPERAND (newexpr, 0) = name;
- tsi = tsi_last (stmts);
- tsi_link_after (&tsi, newexpr, TSI_CONTINUE_LINKING);
- VEC_safe_push (tree, heap, inserted_exprs, newexpr);
- pre_stats.insertions++;
break;
}
+
case tcc_unary:
{
- tree_stmt_iterator tsi;
- tree forced_stmts = NULL;
- tree genop1;
- tree temp;
- tree folded;
tree op1 = TREE_OPERAND (expr, 0);
- genop1 = find_or_generate_expression (block, op1, stmts);
- temp = create_tmp_var (TREE_TYPE (expr), "pretmp");
- add_referenced_tmp_var (temp);
+ tree genop1 = find_or_generate_expression (block, op1, stmts);
folded = fold (build (TREE_CODE (expr), TREE_TYPE (expr),
genop1));
- /* If the generated operand is already GIMPLE min_invariant
- just use it instead of calling force_gimple_operand on it,
- since that may make it not invariant by copying it into an
- assignment. */
- if (!is_gimple_min_invariant (genop1))
- newexpr = force_gimple_operand (folded, &forced_stmts, false, NULL);
- else
- newexpr = genop1;
- if (forced_stmts)
- {
- tsi = tsi_start (forced_stmts);
- for (; !tsi_end_p (tsi); tsi_next (&tsi))
- {
- tree stmt = tsi_stmt (tsi);
- tree forcedname = TREE_OPERAND (stmt, 0);
- tree forcedexpr = TREE_OPERAND (stmt, 1);
- tree val = vn_lookup_or_add (forcedexpr, NULL);
- vn_add (forcedname, val, NULL);
- bitmap_value_replace_in_set (NEW_SETS (block), forcedname);
- bitmap_value_replace_in_set (AVAIL_OUT (block), forcedname);
- }
- tsi = tsi_last (stmts);
- tsi_link_after (&tsi, forced_stmts, TSI_CONTINUE_LINKING);
- }
- newexpr = build (MODIFY_EXPR, TREE_TYPE (expr),
- temp, newexpr);
- name = make_ssa_name (temp, newexpr);
- TREE_OPERAND (newexpr, 0) = name;
- NECESSARY (newexpr) = 0;
- tsi = tsi_last (stmts);
- tsi_link_after (&tsi, newexpr, TSI_CONTINUE_LINKING);
- VEC_safe_push (tree, heap, inserted_exprs, newexpr);
- pre_stats.insertions++;
-
break;
}
+
default:
gcc_unreachable ();
-
}
- v = get_value_handle (expr);
- vn_add (name, v, NULL);
- /* The value may already exist in either NEW_SETS, or AVAIL_OUT, because
+ /* Force the generated expression to be a sequence of GIMPLE
+ statements.
+ We have to call unshare_expr because force_gimple_operand may
+ modify the tree we pass to it. */
+ newexpr = force_gimple_operand (unshare_expr (folded), &forced_stmts,
+ false, NULL);
+
+ /* If we have any intermediate expressions to the value sets, add them
+ to the value sets and chain them on in the instruction stream. */
+ if (forced_stmts)
+ {
+ tsi = tsi_start (forced_stmts);
+ for (; !tsi_end_p (tsi); tsi_next (&tsi))
+ {
+ tree stmt = tsi_stmt (tsi);
+ tree forcedname = TREE_OPERAND (stmt, 0);
+ tree forcedexpr = TREE_OPERAND (stmt, 1);
+ tree val = vn_lookup_or_add (forcedexpr, NULL);
+ vn_add (forcedname, val, NULL);
+ bitmap_value_replace_in_set (NEW_SETS (block), forcedname);
+ bitmap_value_replace_in_set (AVAIL_OUT (block), forcedname);
+ }
+ tsi = tsi_last (stmts);
+ tsi_link_after (&tsi, forced_stmts, TSI_CONTINUE_LINKING);
+ }
+
+ /* Build and insert the assignment of the end result to the temporary
+ that we will return. */
+ temp = create_tmp_var (TREE_TYPE (expr), "pretmp");
+ add_referenced_tmp_var (temp);
+ newexpr = build (MODIFY_EXPR, TREE_TYPE (expr), temp, newexpr);
+ name = make_ssa_name (temp, newexpr);
+ TREE_OPERAND (newexpr, 0) = name;
+ NECESSARY (newexpr) = 0;
+ tsi = tsi_last (stmts);
+ tsi_link_after (&tsi, newexpr, TSI_CONTINUE_LINKING);
+ VEC_safe_push (tree, heap, inserted_exprs, newexpr);
+
+ /* Add a value handle to the temprorary.
+ The value may already exist in either NEW_SETS, or AVAIL_OUT, because
we are creating the expression by pieces, and this particular piece of
the expression may have been represented. There is no harm in replacing
here. */
+ v = get_value_handle (expr);
+ vn_add (name, v, NULL);
bitmap_value_replace_in_set (NEW_SETS (block), name);
bitmap_value_replace_in_set (AVAIL_OUT (block), name);
+
+ pre_stats.insertions++;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Inserted ");
print_generic_expr (dump_file, newexpr, 0);
fprintf (dump_file, " in predecessor %d\n", block->index);
}
+
return name;
}