middle-end/102129 - avoid TER of possibly trapping expressions

The following avoids applying TER to possibly trapping expressions,
preventing a trapping FP multiplication to be moved across a call
that should not be executed.

2021-08-31  Richard Biener  <rguenther@suse.de>

	PR middle-end/102129
	* tree-ssa-ter.c (find_replaceable_in_bb): Do not move
	possibly trapping expressions across calls.

diff --git a/gcc/tree-ssa-ter.c b/gcc/tree-ssa-ter.c
index 9eb8a11a7c0344dc45550979b35b21e23adc3dbb..3a057c2d25f0f485c37d0f5a4856835e10870347 100644 (file)
--- a/gcc/tree-ssa-ter.c
+++ b/gcc/tree-ssa-ter.c
@@ -658,11 +658,15 @@ find_replaceable_in_bb (temp_expr_table *tab, basic_block bb)
                 substitution list, or the def and use span a call such that
                 we'll expand lifetimes across a call.  We also don't want to
                 replace across these expressions that may call libcalls that
-                clobber the register involved.  See PR 70184.  */
+                clobber the register involved.  See PR 70184.  Neither
+                do we want to move possibly trapping expressions across
+                a call.  See PRs 102129 and 33593.  */
              if (gimple_has_volatile_ops (stmt) || same_root_var
                  || (tab->call_cnt[ver] != cur_call_cnt
-                     && SINGLE_SSA_USE_OPERAND (SSA_NAME_DEF_STMT (use), SSA_OP_USE)
-                        == NULL_USE_OPERAND_P)
+                     && (SINGLE_SSA_USE_OPERAND (SSA_NAME_DEF_STMT (use),
+                                                 SSA_OP_USE)
+                           == NULL_USE_OPERAND_P
+                         || gimple_could_trap_p (SSA_NAME_DEF_STMT (use))))
                  || tab->reg_vars_cnt[ver] != cur_reg_vars_cnt)
                finished_with_expr (tab, ver, true);
              else