From: Richard Biener <rguenther@suse.de>
Date: Tue, 4 May 2021 07:18:11 +0000 (+0200)
Subject: tree-optimization/100398 - avoid DSE of control flow stmt
X-Git-Tag: basepoints/gcc-13~7883
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2326627eb19d8c21251fd60479f1a190621c475b;p=thirdparty%2Fgcc.git

tree-optimization/100398 - avoid DSE of control flow stmt

The following makes sure to preserve control altering stmts
when removing trivially dead stmts in DSE.

2021-05-04  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/100398
	* tree-ssa-dse.c (pass_dse::execute): Preserve control
	altering stmts.

	* gcc.dg/torture/pr100398.c: New testcase.
---

diff --git a/gcc/testsuite/gcc.dg/torture/pr100398.c b/gcc/testsuite/gcc.dg/torture/pr100398.c
new file mode 100644
index 000000000000..41eaddee27e4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr100398.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+
+int
+test5_limit (void)
+{
+  int addr;
+
+  asm goto ("" : "+r" (addr) : : : t_err);
+  return 0;
+
+ t_err:
+  return 1;
+}
diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c
index dfa6d3147270..d7cf74770285 100644
--- a/gcc/tree-ssa-dse.c
+++ b/gcc/tree-ssa-dse.c
@@ -1219,6 +1219,7 @@ pass_dse::execute (function *fun)
 		 dead SSA defs.  */
 	      if (has_zero_uses (DEF_FROM_PTR (def_p))
 		  && !gimple_has_side_effects (stmt)
+		  && !is_ctrl_altering_stmt (stmt)
 		  && !stmt_unremovable_because_of_non_call_eh_p (cfun, stmt))
 		{
 		  if (dump_file && (dump_flags & TDF_DETAILS))