From: Jakub Jelinek <jakub@redhat.com>
Date: Tue, 19 Dec 2017 18:10:04 +0000 (+0100)
Subject: re PR tree-optimization/83444 (missing strlen optimization on a member array of a... 
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=ad2a970f7973708ea3359c0b8cc2aec7c9ead1bb;p=gcc.git

re PR tree-optimization/83444 (missing strlen optimization on a member array of a local struct)

	PR tree-optimization/83444
	* tree-ssa-strlen.c (strlen_check_and_optimize_stmt): For the
	character load case, if get_stridx on MEM_REF's operand doesn't
	look usable, retry with get_addr_stridx.

	* gcc.dg/strlenopt-38.c: New test.

From-SVN: r255835
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 328ce281e81..5e8e9bf6acc 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2017-12-19  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/83444
+	* tree-ssa-strlen.c (strlen_check_and_optimize_stmt): For the
+	character load case, if get_stridx on MEM_REF's operand doesn't
+	look usable, retry with get_addr_stridx.
+
 2017-12-19  Alexandre Oliva <aoliva@redhat.com>
 
 	PR debug/83422
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 81f96c6ce07..1146e94c0e9 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -5,6 +5,9 @@
 
 2017-12-19  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/83444
+	* gcc.dg/strlenopt-38.c: New test.
+
 	PR testsuite/83454
 	* gcc.dg/tree-ssa/cswtch-4.c: Require nonpic effective target.
 	* gcc.dg/tree-ssa/cswtch-5.c: Likewise.
diff --git a/gcc/testsuite/gcc.dg/strlenopt-38.c b/gcc/testsuite/gcc.dg/strlenopt-38.c
index 3b698f9c1e8..7c39f3a175b 100644
--- a/gcc/testsuite/gcc.dg/strlenopt-38.c
+++ b/gcc/testsuite/gcc.dg/strlenopt-38.c
@@ -36,3 +36,14 @@ baz (void)
   if (s.b[0] != 0)
     abort ();
 }
+
+void
+boo (void)
+{
+  struct S s;
+  strcpy (s.b, "012");
+  strcpy (s.c, "");
+  strcpy (s.b, s.c);
+  if (strlen (s.b) != 0)
+    abort ();
+}
diff --git a/gcc/tree-ssa-strlen.c b/gcc/tree-ssa-strlen.c
index a2d514cb35a..8971c7df4f3 100644
--- a/gcc/tree-ssa-strlen.c
+++ b/gcc/tree-ssa-strlen.c
@@ -3155,14 +3155,27 @@ strlen_check_and_optimize_stmt (gimple_stmt_iterator *gsi)
 	  {
 	    tree off = integer_zero_node;
 	    unsigned HOST_WIDE_INT coff = 0;
-	    int idx = -1;
+	    int idx = 0;
 	    tree rhs1 = gimple_assign_rhs1 (stmt);
 	    if (code == MEM_REF)
 	      {
 		idx = get_stridx (TREE_OPERAND (rhs1, 0));
-		off = TREE_OPERAND (rhs1, 1);
+		if (idx > 0)
+		  {
+		    strinfo *si = get_strinfo (idx);
+		    if (si
+			&& si->nonzero_chars
+			&& TREE_CODE (si->nonzero_chars) == INTEGER_CST
+			&& (wi::to_widest (si->nonzero_chars)
+			    >= wi::to_widest (off)))
+		      off = TREE_OPERAND (rhs1, 1);
+		    else
+		      /* This case is not useful.  See if get_addr_stridx
+			 returns something usable.  */
+		      idx = 0;
+		  }
 	      }
-	    else
+	    if (idx <= 0)
 	      idx = get_addr_stridx (rhs1, NULL_TREE, &coff);
 	    if (idx > 0)
 	      {