From: Richard Biener <rguenther@suse.de>
Date: Wed, 28 Feb 2018 13:40:41 +0000 (+0000)
Subject: re PR c/84607 (Side effects discarded in address computation inside 'if')
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=9348eb677eb9e113ae7889faa5466723a307941f;p=gcc.git

re PR c/84607 (Side effects discarded in address computation inside 'if')

2018-02-28  Richard Biener  <rguenther@suse.de>

	PR middle-end/84607
	* genmatch.c (capture_info::walk_match): Do not mark
	captured expressions without operands as expr_p given
	they act more like predicates and should be subject to
	"lost tail" side-effect preserving.

	* gcc.dg/pr84607.c: New testcase.

From-SVN: r258061
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8eedfcaaf82..d7f8754d2e9 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2018-02-28  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/84607
+	* genmatch.c (capture_info::walk_match): Do not mark
+	captured expressions without operands as expr_p given
+	they act more like predicates and should be subject to
+	"lost tail" side-effect preserving.
+
 2018-02-28  Alexandre Oliva <aoliva@redhat.com>
 
 	PR rtl-optimization/81611
diff --git a/gcc/genmatch.c b/gcc/genmatch.c
index e2b2cbfe66c..be6efe3bf12 100644
--- a/gcc/genmatch.c
+++ b/gcc/genmatch.c
@@ -2104,7 +2104,11 @@ capture_info::walk_match (operand *o, unsigned toplevel_arg,
       if (c->what
 	  && (e = dyn_cast <expr *> (c->what)))
 	{
-	  info[where].expr_p = true;
+	  /* Zero-operand expression captures like ADDR_EXPR@0 are
+	     similar as predicates -- if they are not mentioned in
+	     the result we have to force them to have no side-effects.  */
+	  if (e->ops.length () != 0)
+	    info[where].expr_p = true;
 	  info[where].force_single_use |= e->force_single_use;
 	}
     }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 252a33a00d4..eaa5041b18d 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-02-28  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/84607
+	* gcc.dg/pr84607.c: New testcase.
+
 2018-02-28  Nathan Sidwell  <nathan@acm.org>
 
 	PR c++/84602
diff --git a/gcc/testsuite/gcc.dg/pr84607.c b/gcc/testsuite/gcc.dg/pr84607.c
new file mode 100644
index 00000000000..710ee94f729
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr84607.c
@@ -0,0 +1,16 @@
+/* { dg-do run } */
+
+extern void exit(int);
+extern void abort(void);
+int a[10];
+int foo()
+{
+  exit (0);
+  return 0;
+}
+int main()
+{
+  if (&a[foo()])
+    abort ();
+  return 0;
+}