From 7a158a5776f5ca95a318fcae0ca2dfefb0789538 Mon Sep 17 00:00:00 2001 From: Alexander Monakov Date: Fri, 14 Jan 2022 21:05:12 +0300 Subject: tree-cfg: check placement of returns_twice calls When a returns_twice call has an associated abnormal edge, the edge corresponds to the "second return" from the call. It wouldn't make sense if any executable statements appeared between the call and the destination of the edge (they wouldn't be re-executed upon the "second return"), so verify that. gcc/ChangeLog: * tree-cfg.cc (gimple_verify_flow_info): Check placement of returns_twice calls. --- gcc/tree-cfg.cc | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) (limited to 'gcc/tree-cfg.cc') diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc index a365aad..5bcf781 100644 --- a/gcc/tree-cfg.cc +++ b/gcc/tree-cfg.cc @@ -5653,6 +5653,7 @@ gimple_verify_flow_info (void) } /* Verify that body of basic block BB is free of control flow. */ + bool seen_nondebug_stmt = false; for (; !gsi_end_p (gsi); gsi_next (&gsi)) { gimple *stmt = gsi_stmt (gsi); @@ -5673,6 +5674,38 @@ gimple_verify_flow_info (void) gimple_label_label (label_stmt), bb->index); err = 1; } + + /* Check that no statements appear between a returns_twice call + and its associated abnormal edge. */ + if (gimple_code (stmt) == GIMPLE_CALL + && gimple_call_flags (stmt) & ECF_RETURNS_TWICE) + { + const char *misplaced = NULL; + /* TM is an exception: it points abnormal edges just after the + call that starts a transaction, i.e. it must end the BB. */ + if (gimple_call_builtin_p (stmt, BUILT_IN_TM_START)) + { + if (single_succ_p (bb) + && bb_has_abnormal_pred (single_succ (bb)) + && !gsi_one_nondebug_before_end_p (gsi)) + misplaced = "not last"; + } + else + { + if (seen_nondebug_stmt + && bb_has_abnormal_pred (bb)) + misplaced = "not first"; + } + if (misplaced) + { + error ("returns_twice call is %s in basic block %d", + misplaced, bb->index); + print_gimple_stmt (stderr, stmt, 0, TDF_SLIM); + err = 1; + } + } + if (!is_gimple_debug (stmt)) + seen_nondebug_stmt = true; } gsi = gsi_last_nondebug_bb (bb); -- cgit v1.1