From 1bdcf037b30e17f8f9182952494c7d98b9a100d1 Mon Sep 17 00:00:00 2001 From: Richard Guenther Date: Wed, 5 Mar 2008 16:13:04 +0000 Subject: [PATCH] re PR tree-optimization/35472 (tree DSE is broken) 2008-03-05 Richard Guenther PR tree-optimization/35472 * tree-ssa-dse.c (dse_optimize_stmt): Do not delete a store whose single use_stmt has a overlapping set of loaded and stored symbols as that use_stmt might be a noop assignment then. * gcc.c-torture/execute/pr35472.c: New testcase. From-SVN: r132899 --- gcc/ChangeLog | 7 ++++ gcc/testsuite/ChangeLog | 5 +++ gcc/testsuite/gcc.c-torture/execute/pr35472.c | 22 +++++++++++++ gcc/tree-ssa-dse.c | 33 +++++++++---------- 4 files changed, 50 insertions(+), 17 deletions(-) create mode 100644 gcc/testsuite/gcc.c-torture/execute/pr35472.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index fe414641c34..a179d15064c 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2008-03-05 Richard Guenther + + PR tree-optimization/35472 + * tree-ssa-dse.c (dse_optimize_stmt): Do not delete a store + whose single use_stmt has a overlapping set of loaded and + stored symbols as that use_stmt might be a noop assignment then. + 2008-03-05 Joel Sherrill * gthr-rtems.h: Implement __gthread_mutex_destroy. diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 8341b280545..98246904330 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2008-03-05 Richard Guenther + + PR tree-optimization/35472 + * gcc.c-torture/execute/pr35472.c: New testcase. + 2007-03-05 Gabor Loki PR 33009 diff --git a/gcc/testsuite/gcc.c-torture/execute/pr35472.c b/gcc/testsuite/gcc.c-torture/execute/pr35472.c new file mode 100644 index 00000000000..c8678e268c9 --- /dev/null +++ b/gcc/testsuite/gcc.c-torture/execute/pr35472.c @@ -0,0 +1,22 @@ +extern void abort (void); +extern void *memset (void *s, int c, __SIZE_TYPE__ n); +struct S { int i[16]; }; +struct S *p; +void __attribute__((noinline)) +foo(struct S *a, struct S *b) { a->i[0] = -1; p = b; } +void test (void) +{ + struct S a, b; + memset (&a.i[0], '\0', sizeof (a.i)); + memset (&b.i[0], '\0', sizeof (b.i)); + foo (&a, &b); + *p = a; + *p = b; + if (b.i[0] != -1) + abort (); +} +int main() +{ + test(); + return 0; +} diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c index 3e0f04be124..f2ec9a505c7 100644 --- a/gcc/tree-ssa-dse.c +++ b/gcc/tree-ssa-dse.c @@ -470,24 +470,23 @@ dse_optimize_stmt (struct dom_walk_data *walk_data, vuse_vec_p vv; tree stmt_lhs; - if (LOADED_SYMS (use_stmt)) + /* If use_stmt is or might be a nop assignment, e.g. for + struct { ... } S a, b, *p; ... + b = a; b = b; + or + b = a; b = *p; where p might be &b, + or + *p = a; *p = b; where p might be &b, + or + *p = *u; *p = *v; where p might be v, then USE_STMT + acts as a use as well as definition, so store in STMT + is not dead. */ + if (LOADED_SYMS (use_stmt) + && bitmap_intersect_p (LOADED_SYMS (use_stmt), + STORED_SYMS (use_stmt))) { - tree use_base - = get_base_address (GIMPLE_STMT_OPERAND (use_stmt, 0)); - /* If use_stmt is or might be a nop assignment, e.g. for - struct { ... } S a, b, *p; ... - b = a; b = b; - or - b = a; b = *p; where p might be &b, then USE_STMT - acts as a use as well as definition, so store in STMT - is not dead. */ - if (TREE_CODE (use_base) == VAR_DECL - && bitmap_bit_p (LOADED_SYMS (use_stmt), - DECL_UID (use_base))) - { - record_voperand_set (dse_gd->stores, &bd->stores, ann->uid); - return; - } + record_voperand_set (dse_gd->stores, &bd->stores, ann->uid); + return; } if (dump_file && (dump_flags & TDF_DETAILS)) -- 2.30.2