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re PR middle-end/64614 (bogus used initialized warning (in gcc 4.9.2); switch statement versus &)

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2015-01-16  Richard Biener  <rguenther@suse.de>

	PR middle-end/64614
	* tree-ssa-uninit.c: Include tree-cfg.h.
	(MAX_SWITCH_CASES): New define.
	(convert_control_dep_chain_into_preds): Handle switch statements.
	(is_pred_expr_subset_of): Handle x == CST vs. (x & CST) != 0.
	(normalize_one_pred_1): Do not split bit-manipulations.
	Record (x & CST).

	* gcc.dg/uninit-18.c: New testcase.

From-SVN: r219739
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Richard Biener 2015-01-16 13:26:10 +00:00 committed by Richard Biener
parent 6220fdff17
commit 666e8e0603
4 changed files with 117 additions and 9 deletions
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10
gcc/ChangeLog
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@ -1,3 +1,13 @@
2015-01-16 Richard Biener <rguenther@suse.de>
PR middle-end/64614
* tree-ssa-uninit.c: Include tree-cfg.h.
(MAX_SWITCH_CASES): New define.
(convert_control_dep_chain_into_preds): Handle switch statements.
(is_pred_expr_subset_of): Handle x == CST vs. (x & CST) != 0.
(normalize_one_pred_1): Do not split bit-manipulations.
Record (x & CST).
2015-01-16 Richard Biener <rguenther@suse.de>
PR tree-optimization/64568

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2015-01-16 Richard Biener <rguenther@suse.de>
PR middle-end/64614
* gcc.dg/uninit-18.c: New testcase.
2015-01-16 Richard Biener <rguenther@suse.de>
PR tree-optimization/64568

24
gcc/testsuite/gcc.dg/uninit-18.c Normal file
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@ -0,0 +1,24 @@
/* { dg-do compile } */
/* { dg-options "-O -Wuninitialized" } */
char *foo(int bar, char *baz)
{
char *tmp;
if (bar & 3)
tmp = baz;
switch (bar) {
case 1:
tmp[5] = 7; /* { dg-bogus "may be used uninitialized" } */
break;
case 2:
tmp[11] = 15; /* { dg-bogus "may be used uninitialized" } */
break;
default:
tmp = 0;
break;
}
return tmp; /* { dg-bogus "may be used uninitialized" } */
}

87
gcc/tree-ssa-uninit.c
View File

@ -58,6 +58,7 @@ along with GCC; see the file COPYING3. If not see
#include "tree-pass.h"
#include "diagnostic-core.h"
#include "params.h"
#include "tree-cfg.h"
/* This implements the pass that does predicate aware warning on uses of
possibly uninitialized variables. The pass first collects the set of
@ -411,6 +412,7 @@ find_control_equiv_block (basic_block bb)
#define MAX_NUM_CHAINS 8
#define MAX_CHAIN_LEN 5
#define MAX_POSTDOM_CHECK 8
#define MAX_SWITCH_CASES 40
/* Computes the control dependence chains (paths of edges)
for DEP_BB up to the dominating basic block BB (the head node of a
@ -592,17 +594,63 @@ convert_control_dep_chain_into_preds (vec<edge> *dep_chains,
if (skip)
continue;
}
if (gimple_code (cond_stmt) != GIMPLE_COND)
if (gimple_code (cond_stmt) == GIMPLE_COND)
{
one_pred.pred_lhs = gimple_cond_lhs (cond_stmt);
one_pred.pred_rhs = gimple_cond_rhs (cond_stmt);
one_pred.cond_code = gimple_cond_code (cond_stmt);
one_pred.invert = !!(e->flags & EDGE_FALSE_VALUE);
t_chain.safe_push (one_pred);
has_valid_pred = true;
}
else if (gswitch *gs = dyn_cast <gswitch *> (cond_stmt))
{
/* Avoid quadratic behavior. */
if (gimple_switch_num_labels (gs) > MAX_SWITCH_CASES)
{
has_valid_pred = false;
break;
}
/* Find the case label. */
tree l = NULL_TREE;
unsigned idx;
for (idx = 0; idx < gimple_switch_num_labels (gs); ++idx)
{
tree tl = gimple_switch_label (gs, idx);
if (e->dest == label_to_block (CASE_LABEL (tl)))
{
if (!l)
l = tl;
else
{
l = NULL_TREE;
break;
}
}
}
/* If more than one label reaches this block or the case
label doesn't have a single value (like the default one)
fail. */
if (!l
|| !CASE_LOW (l)
|| (CASE_HIGH (l) && !operand_equal_p (CASE_LOW (l),
CASE_HIGH (l), 0)))
{
has_valid_pred = false;
break;
}
one_pred.pred_lhs = gimple_switch_index (gs);
one_pred.pred_rhs = CASE_LOW (l);
one_pred.cond_code = EQ_EXPR;
one_pred.invert = false;
t_chain.safe_push (one_pred);
has_valid_pred = true;
}
else
{
has_valid_pred = false;
break;
}
one_pred.pred_lhs = gimple_cond_lhs (cond_stmt);
one_pred.pred_rhs = gimple_cond_rhs (cond_stmt);
one_pred.cond_code = gimple_cond_code (cond_stmt);
one_pred.invert = !!(e->flags & EDGE_FALSE_VALUE);
t_chain.safe_push (one_pred);
has_valid_pred = true;
}
if (!has_valid_pred)
@ -1329,6 +1377,10 @@ is_pred_expr_subset_of (pred_info expr1, pred_info expr2)
if (expr2.invert)
code2 = invert_tree_comparison (code2, false);
if (code1 == EQ_EXPR && code2 == BIT_AND_EXPR)
return wi::eq_p (expr1.pred_rhs,
wi::bit_and (expr1.pred_rhs, expr2.pred_rhs));
if (code1 != code2 && code2 != NE_EXPR)
return false;
@ -1970,8 +2022,25 @@ normalize_one_pred_1 (pred_chain_union *norm_preds,
}
else if (gimple_assign_rhs_code (def_stmt) == and_or_code)
{
push_to_worklist (gimple_assign_rhs1 (def_stmt), work_list, mark_set);
push_to_worklist (gimple_assign_rhs2 (def_stmt), work_list, mark_set);
/* Avoid splitting up bit manipulations like x & 3 or y | 1. */
if (is_gimple_min_invariant (gimple_assign_rhs2 (def_stmt)))
{
/* But treat x & 3 as condition. */
if (and_or_code == BIT_AND_EXPR)
{
pred_info n_pred;
n_pred.pred_lhs = gimple_assign_rhs1 (def_stmt);
n_pred.pred_rhs = gimple_assign_rhs2 (def_stmt);
n_pred.cond_code = and_or_code;
n_pred.invert = false;
norm_chain->safe_push (n_pred);
}
}
else
{
push_to_worklist (gimple_assign_rhs1 (def_stmt), work_list, mark_set);
push_to_worklist (gimple_assign_rhs2 (def_stmt), work_list, mark_set);
}
}
else if (TREE_CODE_CLASS (gimple_assign_rhs_code (def_stmt))
== tcc_comparison)