[PATCH] Fix PR82102

[Richard Biener <rguenther@suse.de>]

The following fixes PR82102, GIMPLE_NOPs don't have a lhs so we
have to care for that case.

Tested on x86_64-unknown-linux-gnu, applied as obvious.

Richard.

2017-09-05  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/82102
	* tree-ssa-pre.c (fini_eliminate): Check if lhs is NULL.

	* gcc.dg/torture/pr82102.c: New testcase.

Index: gcc/tree-ssa-pre.c
===================================================================
--- gcc/tree-ssa-pre.c	(revision 251689)
+++ gcc/tree-ssa-pre.c	(working copy)
@@ -4860,6 +4860,7 @@ fini_eliminate (void)
 	lhs = gimple_get_lhs (stmt);
 
       if (inserted_exprs
+	  && lhs
 	  && TREE_CODE (lhs) == SSA_NAME
 	  && bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (lhs)))
 	continue;
Index: gcc/testsuite/gcc.dg/torture/pr82102.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr82102.c	(nonexistent)
+++ gcc/testsuite/gcc.dg/torture/pr82102.c	(working copy)
@@ -0,0 +1,21 @@
+/* { dg-do compile } */
+
+void *a, *b;
+struct pt3_i2cbuf {
+    int num_cmds;
+} c;
+void *memcpy(void *, void *, __SIZE_TYPE__);
+void put_stop();
+void translate(struct pt3_i2cbuf *p1, int p2)
+{
+  p1->num_cmds = 0;
+  if (p2)
+    put_stop();
+}
+void pt3_i2c_master_xfer(int p1)
+{
+  translate(&c, p1);
+  memcpy(a, b, c.num_cmds);
+  for (; p1;)
+    ;
+}