Zdenek Dvorak <rakd...@kam.mff.cuni.cz> wrote on 30/06/2011 15:21:43:
> From: Zdenek Dvorak <rakd...@kam.mff.cuni.cz>
> To: Razya Ladelsky/Haifa/IBM@IBMIL
> Cc: gcc-patches@gcc.gnu.org, Richard Guenther
<richard.guent...@gmail.com>
> Date: 30/06/2011 15:21
> Subject: Re: PATCH] PR 49580
>
> Hi,
>
> > This patch fixes the build failure of gcc spec2006 benchmark.
> > The change is in gimple_duplicate_sese_tail(), where we need to
subtract
> > 1 from the loop's number of iterations.
> > The stmt created to change the rhs of the loop's condition, used to be
> > inserted right after the defining stmt of the rhs (an ssa name).
> > This requires special handling of different cases of the defining
stmt:
> > 1.gimple_stmt
> > 2.gimple_phi
> > 3.default_def
> >
> > Instead of handling each case separately, if we insert the new stmt at
the
> > begining of the loop's preheader, we're sure that
> > it's already been defined.
> >
> > Bootstrap and testsuite pass successfully (as autopar is not enabled
by
> > default).
> > No new regressions when the testsuite is run with autopar enabled.
> > No new regressions for the run of spec2006 with autopar enabled, and
gcc
> > benchmark now passes successfully..
> >
> > OK for trunk?
>
> actually, I think a better approach would be not to have this kind
> of pass-specific
> adjustments in gimple_duplicate_sese_tail at all. The code
> decreasing the number of
> iterations in gimple_duplicate_sese_tail only works because parloops
> does induction
> variable canonicalization first; should we need it to be used
> anywhere else, it will break.
> I.e., parloops should first transform the condition so that it does
> the comparison with
> the adjusted value, and then gimple_duplicate_sese_tail could do
> just code copying
> and cfg changes,
>
> Zdenek
Hi,
I moved the adjustment of the loop's iterations from
gimple_duplicate_sese_tail
to tree-parloops.c, right before the call to gimple_duplicate_sese_tail.
I repeated the bootstrap, regression and spec runs - no new regressions.
OK to commit?
Thanks,
razya
Index: gcc/tree-parloops.c
===================================================================
--- gcc/tree-parloops.c (revision 174166)
+++ gcc/tree-parloops.c (working copy)
@@ -1464,6 +1464,8 @@ transform_to_exit_first_loop (struct loop *loop, h
gimple phi, nphi, cond_stmt, stmt, cond_nit;
gimple_stmt_iterator gsi;
tree nit_1;
+ edge exit_1;
+ tree new_rhs;
split_block_after_labels (loop->header);
orig_header = single_succ (loop->header);
@@ -1492,6 +1494,38 @@ transform_to_exit_first_loop (struct loop *loop, h
control = t;
}
}
+
+ /* Setting the condition towards peeling the last iteration:
+ If the block consisting of the exit condition has the latch as
+ successor, then the body of the loop is executed before
+ the exit condition is tested. In such case, moving the
+ condition to the entry, causes that the loop will iterate
+ one less iteration (which is the wanted outcome, since we
+ peel out the last iteration). If the body is executed after
+ the condition, moving the condition to the entry requires
+ decrementing one iteration. */
+ exit_1 = EDGE_SUCC (exit->src, EDGE_SUCC (exit->src, 0) == exit);
+ if (exit_1->dest == loop->latch)
+ new_rhs = gimple_cond_rhs (cond_stmt);
+ else
+ {
+ new_rhs = fold_build2 (MINUS_EXPR, TREE_TYPE (gimple_cond_rhs (cond_stmt)),
+ gimple_cond_rhs (cond_stmt),
+ build_int_cst (TREE_TYPE (gimple_cond_rhs
(cond_stmt)), 1));
+ if (TREE_CODE (gimple_cond_rhs (cond_stmt)) == SSA_NAME)
+ {
+ basic_block preheader;
+ gimple_stmt_iterator gsi1;
+
+ preheader = loop_preheader_edge(loop)->src;
+ gsi1 = gsi_after_labels (preheader);
+ new_rhs = force_gimple_operand_gsi (&gsi1, new_rhs, true,
+
NULL_TREE,false,GSI_CONTINUE_LINKING);
+ }
+ }
+ gimple_cond_set_rhs (cond_stmt, unshare_expr (new_rhs));
+ gimple_cond_set_lhs (cond_stmt, unshare_expr (gimple_cond_lhs (cond_stmt)));
+
bbs = get_loop_body_in_dom_order (loop);
for (n = 0; bbs[n] != loop->latch; n++)
Index: gcc/tree-cfg.c
===================================================================
--- gcc/tree-cfg.c (revision 174166)
+++ gcc/tree-cfg.c (working copy)
@@ -5397,12 +5397,10 @@ gimple_duplicate_sese_tail (edge entry ATTRIBUTE_U
int total_freq = 0, exit_freq = 0;
gcov_type total_count = 0, exit_count = 0;
edge exits[2], nexits[2], e;
- gimple_stmt_iterator gsi,gsi1;
+ gimple_stmt_iterator gsi;
gimple cond_stmt;
edge sorig, snew;
basic_block exit_bb;
- basic_block iters_bb;
- tree new_rhs;
gimple_stmt_iterator psi;
gimple phi;
tree def;
@@ -5483,35 +5481,6 @@ gimple_duplicate_sese_tail (edge entry ATTRIBUTE_U
gcc_assert (gimple_code (cond_stmt) == GIMPLE_COND);
cond_stmt = gimple_copy (cond_stmt);
- /* If the block consisting of the exit condition has the latch as
- successor, then the body of the loop is executed before
- the exit condition is tested. In such case, moving the
- condition to the entry, causes that the loop will iterate
- one less iteration (which is the wanted outcome, since we
- peel out the last iteration). If the body is executed after
- the condition, moving the condition to the entry requires
- decrementing one iteration. */
- if (exits[1]->dest == orig_loop->latch)
- new_rhs = gimple_cond_rhs (cond_stmt);
- else
- {
- new_rhs = fold_build2 (MINUS_EXPR, TREE_TYPE (gimple_cond_rhs (cond_stmt)),
- gimple_cond_rhs (cond_stmt),
- build_int_cst (TREE_TYPE (gimple_cond_rhs
(cond_stmt)), 1));
-
- if (TREE_CODE (gimple_cond_rhs (cond_stmt)) == SSA_NAME)
- {
- iters_bb = gimple_bb (SSA_NAME_DEF_STMT (gimple_cond_rhs (cond_stmt)));
- for (gsi1 = gsi_start_bb (iters_bb); !gsi_end_p (gsi1); gsi_next
(&gsi1))
- if (gsi_stmt (gsi1) == SSA_NAME_DEF_STMT (gimple_cond_rhs
(cond_stmt)))
- break;
-
- new_rhs = force_gimple_operand_gsi (&gsi1, new_rhs, true,
-
NULL_TREE,false,GSI_CONTINUE_LINKING);
- }
- }
- gimple_cond_set_rhs (cond_stmt, unshare_expr (new_rhs));
- gimple_cond_set_lhs (cond_stmt, unshare_expr (gimple_cond_lhs (cond_stmt)));
gsi_insert_after (&gsi, cond_stmt, GSI_NEW_STMT);
sorig = single_succ_edge (switch_bb);
=
07-05-2011 Razya Ladelsky <ra...@il.ibm.com>
* tree-cfg.c (gimple_duplicate_sese_tail): Remove handling of
the loop's number of iterations.
* tree-parloops.c (transform_to_exit_first_loop): Add the
handling of the loop's number of iterations before the call
to gimple_duplicate_sese_tail.
Insert the stmt caclculating the new rhs of the loop's
condition stmt to the preheader instead of iters_bb.
=
