| Message ID | 20110701212148.GK16443@tyan-ft48-01.lab.bos.redhat.com |
|---|---|
| State | New |
| Headers | show |
On Fri, Jul 1, 2011 at 11:21 PM, Jakub Jelinek <jakub@redhat.com> wrote: > Hi! > > For debug stmt uses, we don't want any PHI nodes to be created > just because of them, so the debug uses need to be ignored > during decisions which PHI nodes to add. > Unfortunately that means get_current_def can't be always trusted. > The following patch trusts it in a few cases where I'm reasonably > sure it is trustable. Perhaps some more cases could be added in > the future if anyone has ideas... > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? Ok. Thanks, Richard. > 2011-07-01 Jakub Jelinek <jakub@redhat.com> > > PR debug/49602 > * tree-into-ssa.c (rewrite_debug_stmt_uses): Disregard > get_current_def return value if it can't be trusted to be > the current value of the variable in the current bb. > > * gcc.dg/pr49602.c: New test. > > --- gcc/tree-into-ssa.c.jj 2011-06-23 10:13:58.000000000 +0200 > +++ gcc/tree-into-ssa.c 2011-07-01 20:39:40.000000000 +0200 > @@ -1343,7 +1343,41 @@ rewrite_debug_stmt_uses (gimple stmt) > } > } > else > - def = get_current_def (var); > + { > + def = get_current_def (var); > + /* Check if get_current_def can be trusted. */ > + if (def) > + { > + basic_block bb = gimple_bb (stmt); > + basic_block def_bb > + = SSA_NAME_IS_DEFAULT_DEF (def) > + ? NULL : gimple_bb (SSA_NAME_DEF_STMT (def)); > + > + /* If definition is in current bb, it is fine. */ > + if (bb == def_bb) > + ; > + /* If definition bb doesn't dominate the current bb, > + it can't be used. */ > + else if (def_bb && !dominated_by_p (CDI_DOMINATORS, bb, def_bb)) > + def = NULL; > + /* If there is just one definition and dominates the current > + bb, it is fine. */ > + else if (get_phi_state (var) == NEED_PHI_STATE_NO) > + ; > + else > + { > + struct def_blocks_d *db_p = get_def_blocks_for (var); > + > + /* If there are some non-debug uses in the current bb, > + it is fine. */ > + if (bitmap_bit_p (db_p->livein_blocks, bb->index)) > + ; > + /* Otherwise give up for now. */ > + else > + def = NULL; > + } > + } > + } > if (def == NULL) > { > gimple_debug_bind_reset_value (stmt); > --- gcc/testsuite/gcc.dg/pr49602.c.jj 2011-07-01 20:42:44.000000000 +0200 > +++ gcc/testsuite/gcc.dg/pr49602.c 2011-07-01 18:49:04.000000000 +0200 > @@ -0,0 +1,17 @@ > +/* PR debug/49602 */ > +/* { dg-do compile } */ > +/* { dg-options "-g -O2" } */ > + > +static void > +foo (int *x) > +{ > +} > + > +void > +bar (int *x) > +{ > + int i; > + for (i = 0; i == 1; ++i) > + x = 0; > + foo (x); > +} > > Jakub >
--- gcc/tree-into-ssa.c.jj 2011-06-23 10:13:58.000000000 +0200 +++ gcc/tree-into-ssa.c 2011-07-01 20:39:40.000000000 +0200 @@ -1343,7 +1343,41 @@ rewrite_debug_stmt_uses (gimple stmt) } } else - def = get_current_def (var); + { + def = get_current_def (var); + /* Check if get_current_def can be trusted. */ + if (def) + { + basic_block bb = gimple_bb (stmt); + basic_block def_bb + = SSA_NAME_IS_DEFAULT_DEF (def) + ? NULL : gimple_bb (SSA_NAME_DEF_STMT (def)); + + /* If definition is in current bb, it is fine. */ + if (bb == def_bb) + ; + /* If definition bb doesn't dominate the current bb, + it can't be used. */ + else if (def_bb && !dominated_by_p (CDI_DOMINATORS, bb, def_bb)) + def = NULL; + /* If there is just one definition and dominates the current + bb, it is fine. */ + else if (get_phi_state (var) == NEED_PHI_STATE_NO) + ; + else + { + struct def_blocks_d *db_p = get_def_blocks_for (var); + + /* If there are some non-debug uses in the current bb, + it is fine. */ + if (bitmap_bit_p (db_p->livein_blocks, bb->index)) + ; + /* Otherwise give up for now. */ + else + def = NULL; + } + } + } if (def == NULL) { gimple_debug_bind_reset_value (stmt); --- gcc/testsuite/gcc.dg/pr49602.c.jj 2011-07-01 20:42:44.000000000 +0200 +++ gcc/testsuite/gcc.dg/pr49602.c 2011-07-01 18:49:04.000000000 +0200 @@ -0,0 +1,17 @@ +/* PR debug/49602 */ +/* { dg-do compile } */ +/* { dg-options "-g -O2" } */ + +static void +foo (int *x) +{ +} + +void +bar (int *x) +{ + int i; + for (i = 0; i == 1; ++i) + x = 0; + foo (x); +}