use_after_inval_p uses stmt UIDs to speed up repeated dominance
checks within a basic-block but it fails to assign UIDs to PHIs
which means compares with PHIs in the same block get a random
result.
The following factors renumber_gimple_stmt_uids to expose a new
renumber_gimple_stmt_uids_in_block we can share.
This XFAILs the conditional loop case in gcc.dg/Wuse-after-free-2.c
Bootstrap and regtest running on x86_64-unknown-linux-gnu. This
makes 2/2 a net positive on the testsuite (the early waccess
would not run into this bug)
OK if testing succeeds? (we could also special-case PHIs somehow
and assert we never get to compare two PHIs here)
* tree-dfa.h (renumber_gimple_stmt_uids_in_block): New.
* tree-dfa.cc (renumber_gimple_stmt_uids_in_block): Split
out from ...
(renumber_gimple_stmt_uids): ... here and
(renumber_gimple_stmt_uids_in_blocks): ... here.
* gimple-ssa-warn-access.cc (pass_waccess::use_after_inval_p):
Use renumber_gimple_stmt_uids_in_block to also assign UIDs
to PHIs.
* gcc.dg/Wuse-after-free-2.c: XFAIL conditional loop case.
---
gcc/gimple-ssa-warn-access.cc | 8 +---
gcc/testsuite/gcc.dg/Wuse-after-free-2.c | 4 +-
gcc/tree-dfa.cc | 48 +++++++++++-------------
gcc/tree-dfa.h | 1 +
4 files changed, 25 insertions(+), 36 deletions(-)
diff --git a/gcc/gimple-ssa-warn-access.cc b/gcc/gimple-ssa-warn-access.cc
index 8b1c1cc019e..a8ad7a6df65 100644
--- a/gcc/gimple-ssa-warn-access.cc
+++ b/gcc/gimple-ssa-warn-access.cc
@@ -3862,13 +3862,7 @@ pass_waccess::use_after_inval_p (gimple *inval_stmt,
gimple *use_stmt,
to consecutive statements in it. Use the ids to determine which
precedes which. This avoids the linear traversal on subsequent
visits to the same block. */
- for (auto si = gsi_start_bb (inval_bb); !gsi_end_p (si);
- gsi_next_nondebug (&si))
- {
- gimple *stmt = gsi_stmt (si);
- unsigned uid = inc_gimple_stmt_max_uid (m_func);
- gimple_set_uid (stmt, uid);
- }
+ renumber_gimple_stmt_uids_in_block (m_func, inval_bb);
return gimple_uid (inval_stmt) < gimple_uid (use_stmt);
}
diff --git a/gcc/testsuite/gcc.dg/Wuse-after-free-2.c
b/gcc/testsuite/gcc.dg/Wuse-after-free-2.c
index ebc051690db..cd5c43c0fa3 100644
--- a/gcc/testsuite/gcc.dg/Wuse-after-free-2.c
+++ b/gcc/testsuite/gcc.dg/Wuse-after-free-2.c
@@ -113,6 +113,6 @@ int warn_cond_loop (char *p)
while (*q)
++q;
- free (p); // { dg-message "call to 'free'" }
- return *q; // { dg-warning "pointer 'q' used after 'free'" }
+ free (p); // dg-message "call to 'free'"
+ return *q; // { dg-warning "pointer 'q' used after 'free'" "" { xfail
*-*-* } }
}
diff --git a/gcc/tree-dfa.cc b/gcc/tree-dfa.cc
index ec8df0d6401..82803a8ccb1 100644
--- a/gcc/tree-dfa.cc
+++ b/gcc/tree-dfa.cc
@@ -59,6 +59,25 @@ static void collect_dfa_stats (struct dfa_stats_d *);
Dataflow analysis (DFA) routines
---------------------------------------------------------------------------*/
+/* Renumber the gimple stmt uids in one block. The caller is responsible
+ of calling set_gimple_stmt_max_uid (fun, 0) at some point. */
+
+void
+renumber_gimple_stmt_uids_in_block (struct function *fun, basic_block bb)
+{
+ gimple_stmt_iterator bsi;
+ for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi); gsi_next (&bsi))
+ {
+ gimple *stmt = gsi_stmt (bsi);
+ gimple_set_uid (stmt, inc_gimple_stmt_max_uid (fun));
+ }
+ for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
+ {
+ gimple *stmt = gsi_stmt (bsi);
+ gimple_set_uid (stmt, inc_gimple_stmt_max_uid (fun));
+ }
+}
+
/* Renumber all of the gimple stmt uids. */
void
@@ -68,19 +87,7 @@ renumber_gimple_stmt_uids (struct function *fun)
set_gimple_stmt_max_uid (fun, 0);
FOR_ALL_BB_FN (bb, fun)
- {
- gimple_stmt_iterator bsi;
- for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi); gsi_next (&bsi))
- {
- gimple *stmt = gsi_stmt (bsi);
- gimple_set_uid (stmt, inc_gimple_stmt_max_uid (fun));
- }
- for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
- {
- gimple *stmt = gsi_stmt (bsi);
- gimple_set_uid (stmt, inc_gimple_stmt_max_uid (fun));
- }
- }
+ renumber_gimple_stmt_uids_in_block (fun, bb);
}
/* Like renumber_gimple_stmt_uids, but only do work on the basic blocks
@@ -93,20 +100,7 @@ renumber_gimple_stmt_uids_in_blocks (basic_block *blocks,
int n_blocks)
set_gimple_stmt_max_uid (cfun, 0);
for (i = 0; i < n_blocks; i++)
- {
- basic_block bb = blocks[i];
- gimple_stmt_iterator bsi;
- for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi); gsi_next (&bsi))
- {
- gimple *stmt = gsi_stmt (bsi);
- gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));
- }
- for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
- {
- gimple *stmt = gsi_stmt (bsi);
- gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));
- }
- }
+ renumber_gimple_stmt_uids_in_block (cfun, blocks[i]);
}
diff --git a/gcc/tree-dfa.h b/gcc/tree-dfa.h
index 1632487c3ed..074a4da3a6c 100644
--- a/gcc/tree-dfa.h
+++ b/gcc/tree-dfa.h
@@ -20,6 +20,7 @@ along with GCC; see the file COPYING3. If not see
#ifndef GCC_TREE_DFA_H
#define GCC_TREE_DFA_H
+extern void renumber_gimple_stmt_uids_in_block (struct function *,
basic_block);
extern void renumber_gimple_stmt_uids (struct function *);
extern void renumber_gimple_stmt_uids_in_blocks (basic_block *, int);
extern void dump_variable (FILE *, tree);
--
2.35.3
