diff options
| -rw-r--r-- | gcc/ChangeLog | 7 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.c-torture/execute/20071219-1.c | 71 | ||||
| -rw-r--r-- | gcc/tree-ssa-dse.c | 20 |
4 files changed, 103 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 070123d..33922e0 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2007-12-20 Jakub Jelinek <jakub@redhat.com> + + PR c++/34459 + * tree-ssa-dse.c (dse_optimize_stmt): Don't eliminate store if + USE_STMT not only stores into the same object as STMT, but might + read it too. + 2007-12-19 Sebastian Pop <sebastian.pop@amd.com> PR tree-optimization/34413 diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 3c67c45..e9364ec 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2007-12-20 Jakub Jelinek <jakub@redhat.com> + + PR c++/34459 + * gcc.c-torture/execute/20071219-1.c: New test. + 2007-12-20 Tobias Burnus <burnus@net-b.de> PR fortran/34530 diff --git a/gcc/testsuite/gcc.c-torture/execute/20071219-1.c b/gcc/testsuite/gcc.c-torture/execute/20071219-1.c new file mode 100644 index 0000000..4152711 --- /dev/null +++ b/gcc/testsuite/gcc.c-torture/execute/20071219-1.c @@ -0,0 +1,71 @@ +/* PR c++/34459 */ + +extern void abort (void); +extern void *memset (void *s, int c, __SIZE_TYPE__ n); + +struct S +{ + char s[25]; +}; + +struct S *p; + +void __attribute__((noinline)) +foo (struct S *x, int set) +{ + int i; + for (i = 0; i < sizeof (x->s); ++i) + if (x->s[i] != 0) + abort (); + else if (set) + x->s[i] = set; + p = x; +} + +void __attribute__((noinline)) +test1 (void) +{ + struct S a; + memset (&a.s, '\0', sizeof (a.s)); + foo (&a, 0); + struct S b = a; + foo (&b, 1); + b = a; + b = b; + foo (&b, 0); +} + +void __attribute__((noinline)) +test2 (void) +{ + struct S a; + memset (&a.s, '\0', sizeof (a.s)); + foo (&a, 0); + struct S b = a; + foo (&b, 1); + b = a; + b = *p; + foo (&b, 0); +} + +void __attribute__((noinline)) +test3 (void) +{ + struct S a; + memset (&a.s, '\0', sizeof (a.s)); + foo (&a, 0); + struct S b = a; + foo (&b, 1); + *p = a; + *p = b; + foo (&b, 0); +} + +int +main (void) +{ + test1 (); + test2 (); + test3 (); + return 0; +} diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c index 3435fa3..3e0f04b 100644 --- a/gcc/tree-ssa-dse.c +++ b/gcc/tree-ssa-dse.c @@ -470,6 +470,26 @@ dse_optimize_stmt (struct dom_walk_data *walk_data, vuse_vec_p vv; tree stmt_lhs; + if (LOADED_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; + } + } + if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, " Deleted dead store '"); |