On December 14, 2015 9:11:39 PM GMT+01:00, Jakub Jelinek <ja...@redhat.com>
wrote:
>Hi!
>
>As the testcase used to show on ppc64le with slightly older trunk,
>cleanup_control_flow_bb can be called on a bb with newly noreturn
>call followed by debug stmts. With -g0, cleanup_control_flow_bb
>removes the fallthru edge, so we need to do it even if followed by
>debug
>stmts.
>
>This patch is one possible way to fix this, another one is attached to
>the
>PR.
>
>Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
Thanks,
Richard.
>2015-12-14 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/66688
> * tree-cfgcleanup.c (cleanup_control_flow_bb): Handle
> noreturn call followed only by debug stmts by removing
> the debug stmts and handling it the same as if the noreturn
> call is the last stmt.
>
> * gcc.dg/pr66688.c: New test.
>
>--- gcc/tree-cfgcleanup.c.jj 2015-12-02 20:26:59.000000000 +0100
>+++ gcc/tree-cfgcleanup.c 2015-12-14 17:34:10.748487811 +0100
>@@ -186,7 +186,7 @@ cleanup_control_flow_bb (basic_block bb)
> we need to prune cfg. */
> retval |= gimple_purge_dead_eh_edges (bb);
>
>- gsi = gsi_last_bb (bb);
>+ gsi = gsi_last_nondebug_bb (bb);
> if (gsi_end_p (gsi))
> return retval;
>
>@@ -197,7 +197,10 @@ cleanup_control_flow_bb (basic_block bb)
>
> if (gimple_code (stmt) == GIMPLE_COND
> || gimple_code (stmt) == GIMPLE_SWITCH)
>- retval |= cleanup_control_expr_graph (bb, gsi);
>+ {
>+ gcc_checking_assert (gsi_stmt (gsi_last_bb (bb)) == stmt);
>+ retval |= cleanup_control_expr_graph (bb, gsi);
>+ }
> else if (gimple_code (stmt) == GIMPLE_GOTO
> && TREE_CODE (gimple_goto_dest (stmt)) == ADDR_EXPR
> && (TREE_CODE (TREE_OPERAND (gimple_goto_dest (stmt), 0))
>@@ -210,6 +213,7 @@ cleanup_control_flow_bb (basic_block bb)
> edge_iterator ei;
> basic_block target_block;
>
>+ gcc_checking_assert (gsi_stmt (gsi_last_bb (bb)) == stmt);
> /* First look at all the outgoing edges. Delete any outgoing
> edges which do not go to the right block. For the one
> edge which goes to the right block, fix up its flags. */
>@@ -242,9 +246,15 @@ cleanup_control_flow_bb (basic_block bb)
> /* Check for indirect calls that have been turned into
> noreturn calls. */
> else if (is_gimple_call (stmt)
>- && gimple_call_noreturn_p (stmt)
>- && remove_fallthru_edge (bb->succs))
>- retval = true;
>+ && gimple_call_noreturn_p (stmt))
>+ {
>+ /* If there are debug stmts after the noreturn call, remove them
>+ now, they should be all unreachable anyway. */
>+ for (gsi_next (&gsi); !gsi_end_p (gsi); )
>+ gsi_remove (&gsi, true);
>+ if (remove_fallthru_edge (bb->succs))
>+ retval = true;
>+ }
>
> return retval;
> }
>--- gcc/testsuite/gcc.dg/pr66688.c.jj 2015-12-14 14:51:43.652481658
>+0100
>+++ gcc/testsuite/gcc.dg/pr66688.c 2015-12-14 14:51:05.000000000 +0100
>@@ -0,0 +1,39 @@
>+/* PR tree-optimization/66688 */
>+/* { dg-do compile } */
>+/* { dg-options "-O2 -fno-reorder-blocks -fcompare-debug" } */
>+
>+struct fdt_header { unsigned magic; } *a;
>+
>+int d;
>+
>+int
>+__fswab32 (int p1)
>+{
>+ return __builtin_bswap32 (p1);
>+}
>+
>+void
>+fdt_set_magic (int p1)
>+{
>+ struct fdt_header *b = a;
>+ b->magic = __builtin_constant_p (p1) ? : __fswab32 (p1);
>+}
>+
>+int
>+_fdt_sw_check_header ()
>+{
>+ int c = ((struct fdt_header *) 1)->magic;
>+ if (c)
>+ return 1;
>+ return 0;
>+}
>+
>+int
>+fdt_finish ()
>+{
>+ if (_fdt_sw_check_header ())
>+ if (d)
>+ return 0;
>+ fdt_set_magic (0);
>+ return 0;
>+}
>
> Jakub
