[PATCH] middle-end/102129 - avoid TER of possibly trapping expressions

Richard Biener rguenther@suse.de
Tue Aug 31 09:37:47 GMT 2021


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.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

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.
---
 gcc/tree-ssa-ter.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/gcc/tree-ssa-ter.c b/gcc/tree-ssa-ter.c
index 9eb8a11a7c0..3a057c2d25f 100644
--- 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
-- 
2.31.1


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