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re PR tree-optimization/20640 (ICE on NULL PHI_ARG_DEF)

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gcc/ChangeLog:
PR tree-optimization/20640
* tree-ssa-dce.c (remove_dead_stmt): Don't redirect edge to
post-dominator if it has phi nodes.
(eliminate_unnecessary_stmts): Remove dead phis in all blocks
before dead statements.
gcc/testsuite/ChangeLog:
PR tree-optimization/20640
* gcc.dg/torture/tree-loop-1.c: New.

From-SVN: r97446
This commit is contained in:
Alexandre Oliva 2005-04-02 17:02:15 +00:00 committed by Alexandre Oliva
parent bbe3791247
commit e18d4a1904
4 changed files with 52 additions and 3 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2005-04-02 Alexandre Oliva <aoliva@redhat.com>
PR tree-optimization/20640
* tree-ssa-dce.c (remove_dead_stmt): Don't redirect edge to
post-dominator if it has phi nodes.
(eliminate_unnecessary_stmts): Remove dead phis in all blocks
before dead statements.
2005-04-02 Alexandre Oliva <aoliva@redhat.com>
PR middle-end/20491

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2005-04-02 Alexandre Oliva <aoliva@redhat.com>
PR tree-optimization/20640
* gcc.dg/torture/tree-loop-1.c: New.
2005-04-02 Alexandre Oliva <aoliva@redhat.com>
PR rtl-optimization/20290

21
gcc/testsuite/gcc.dg/torture/tree-loop-1.c Normal file
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@ -0,0 +1,21 @@
/* PR tree-optimization/20640 */
/* After unrolling the loop, we'd turn some conditional branches into
unconditional ones, but branch redirection would fail to compute
the PHI args for the PHI nodes in the replacement edge
destination, so they'd remain NULL causing crashes later on. */
/* { dg-do compile } */
static int a = 0;
extern int foo (void);
extern int *bar (void) __attribute__ ((__const__));
void
test (int x)
{
int b = 10;
while (foo () == -1 && *bar () == 4 && b > 0)
--b;
a = x;
}

21
gcc/tree-ssa-dce.c
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@ -637,7 +637,10 @@ eliminate_unnecessary_stmts (void)
{
/* Remove dead PHI nodes. */
remove_dead_phis (bb);
}
FOR_EACH_BB (bb)
{
/* Remove dead statements. */
for (i = bsi_start (bb); ! bsi_end_p (i) ; )
{
@ -724,6 +727,7 @@ remove_dead_stmt (block_stmt_iterator *i, basic_block bb)
if (is_ctrl_stmt (t))
{
basic_block post_dom_bb;
/* The post dominance info has to be up-to-date. */
gcc_assert (dom_computed[CDI_POST_DOMINATORS] == DOM_OK);
/* Get the immediate post dominator of bb. */
@ -737,9 +741,20 @@ remove_dead_stmt (block_stmt_iterator *i, basic_block bb)
return;
}
/* Redirect the first edge out of BB to reach POST_DOM_BB. */
redirect_edge_and_branch (EDGE_SUCC (bb, 0), post_dom_bb);
PENDING_STMT (EDGE_SUCC (bb, 0)) = NULL;
/* If the post dominator block has PHI nodes, we might be unable
to compute the right PHI args for them. Since the control
statement is unnecessary, all edges can be regarded as
equivalent, but we have to get rid of the condition, since it
might reference a variable that was determined to be
unnecessary and thus removed. */
if (phi_nodes (post_dom_bb))
post_dom_bb = EDGE_SUCC (bb, 0)->dest;
else
{
/* Redirect the first edge out of BB to reach POST_DOM_BB. */
redirect_edge_and_branch (EDGE_SUCC (bb, 0), post_dom_bb);
PENDING_STMT (EDGE_SUCC (bb, 0)) = NULL;
}
EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
EDGE_SUCC (bb, 0)->count = bb->count;