CFG cleanup is now set up to perform trivial unreachable code
elimination before doing anything that would require up-to-date
SSA form. Unfortunately a pending SSA update still will cause
breakage to stmt folding triggered for example by basic-block
merging.
Fortunately it's now easy to properly "interleave" CFG cleanup
and SSA update.
Done as follows, bootstrap & regtest running on x86_64-unknown-linux-gnu.
Richard.
2019-02-27 Richard Biener <rguent...@suse.de>
PR middle-end/89497
* tree-cfgcleanup.h (cleanup_tree_cfg): Add SSA update flags
argument, defaulted to zero.
* passes.c (execute_function_todo): Pass down SSA update flags
to cleanup_tree_cfg.
* tree-cfgcleanup.c: Include tree-into-ssa.h and tree-cfgcleanup.h.
(cleanup_tree_cfg_noloop): After cleanup_control_flow_pre update SSA
form if requested.
(cleanup_tree_cfg): Get and pass down SSA update flags.
Index: gcc/tree-cfgcleanup.h
===================================================================
--- gcc/tree-cfgcleanup.h (revision 269251)
+++ gcc/tree-cfgcleanup.h (working copy)
@@ -22,7 +22,7 @@ along with GCC; see the file COPYING3.
/* In tree-cfgcleanup.c */
extern bitmap cfgcleanup_altered_bbs;
-extern bool cleanup_tree_cfg (void);
+extern bool cleanup_tree_cfg (unsigned = 0);
extern bool fixup_noreturn_call (gimple *stmt);
extern bool delete_unreachable_blocks_update_callgraph (cgraph_node *dst_node,
bool update_clones);
Index: gcc/passes.c
===================================================================
--- gcc/passes.c (revision 269251)
+++ gcc/passes.c (working copy)
@@ -1927,7 +1927,7 @@ execute_function_todo (function *fn, voi
/* Always cleanup the CFG before trying to update SSA. */
if (flags & TODO_cleanup_cfg)
{
- cleanup_tree_cfg ();
+ cleanup_tree_cfg (flags & TODO_update_ssa_any);
/* When cleanup_tree_cfg merges consecutive blocks, it may
perform some simplistic propagation when removing single
Index: gcc/tree-cfgcleanup.c
===================================================================
--- gcc/tree-cfgcleanup.c (revision 269251)
+++ gcc/tree-cfgcleanup.c (working copy)
@@ -44,6 +44,9 @@ along with GCC; see the file COPYING3.
#include "gimple-fold.h"
#include "tree-ssa-loop-niter.h"
#include "cgraph.h"
+#include "tree-into-ssa.h"
+#include "tree-cfgcleanup.h"
+
/* The set of blocks in that at least one of the following changes happened:
-- the statement at the end of the block was changed
@@ -943,7 +946,7 @@ mfb_keep_latches (edge e)
Return true if the flowgraph was modified, false otherwise. */
static bool
-cleanup_tree_cfg_noloop (void)
+cleanup_tree_cfg_noloop (unsigned ssa_update_flags)
{
timevar_push (TV_TREE_CLEANUP_CFG);
@@ -1023,6 +1026,8 @@ cleanup_tree_cfg_noloop (void)
/* After doing the above SSA form should be valid (or an update SSA
should be required). */
+ if (ssa_update_flags)
+ update_ssa (ssa_update_flags);
/* Compute dominator info which we need for the iterative process below. */
if (!dom_info_available_p (CDI_DOMINATORS))
@@ -1125,9 +1130,9 @@ repair_loop_structures (void)
/* Cleanup cfg and repair loop structures. */
bool
-cleanup_tree_cfg (void)
+cleanup_tree_cfg (unsigned ssa_update_flags)
{
- bool changed = cleanup_tree_cfg_noloop ();
+ bool changed = cleanup_tree_cfg_noloop (ssa_update_flags);
if (current_loops != NULL
&& loops_state_satisfies_p (LOOPS_NEED_FIXUP))
