re PR tree-optimization/71104 (ICE: verify_ssa failed (with vfork / error:…

re PR tree-optimization/71104 (ICE: verify_ssa failed (with vfork /  error: definition in block 3 does not dominate use in block 7 ))

2016-07-13  Richard Biener  <rguenther@suse.de>

	PR middle-end/71104
	* gimplify.c (gimplify_modify_expr): Gimplify the RHS before
	gimplifying the LHS.  Make sure to gimplify a returning twice
	call LHS without using SSA names.

	* gcc.dg/pr71104-1.c: New testcase.
	* gcc.dg/pr71104-2.c: Likewise.

From-SVN: r238287

gcc/ChangeLog

+2016-07-13  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/71104
+	* gimplify.c (gimplify_modify_expr): Gimplify the RHS before
+	gimplifying the LHS.  Make sure to gimplify a returning twice
+	call LHS without using SSA names.
+
 2016-07-12  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>
 
 	* tree-data-ref.c (find_data_references_in_stmt): Remove

gcc/gimplify.c

@@ -4810,7 +4810,19 @@ gimplify_modify_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
     return ret;
 
   /* Then gimplify the LHS.  */
+  /* If we gimplified the RHS to a CALL_EXPR and that call may return
+     twice we have to make sure to gimplify into non-SSA as otherwise
+     the abnormal edge added later will make those defs not dominate
+     their uses.
+     ???  Technically this applies only to the registers used in the
+     resulting non-register *TO_P.  */
+  bool saved_into_ssa = gimplify_ctxp->into_ssa;
+  if (saved_into_ssa
+      && TREE_CODE (*from_p) == CALL_EXPR
+      && call_expr_flags (*from_p) & ECF_RETURNS_TWICE)
+    gimplify_ctxp->into_ssa = false;
   ret = gimplify_expr (to_p, pre_p, post_p, is_gimple_lvalue, fb_lvalue);
+  gimplify_ctxp->into_ssa = saved_into_ssa;
   if (ret == GS_ERROR)
     return ret;
 

gcc/testsuite/ChangeLog

+2016-07-13  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/71104
+	* gcc.dg/pr71104-1.c: New testcase.
+	* gcc.dg/pr71104-2.c: Likewise.
+
 2016-07-12  Michael Meissner  <meissner@linux.vnet.ibm.com>
 
 	PR target/71805

gcc/testsuite/gcc.dg/pr71104-1.c

+/* { dg-do compile } */
+
+void foo(void);
+int vfork(void);
+int *p;
+
+void bar(void)
+{
+  foo();
+  *p = vfork();
+}

gcc/testsuite/gcc.dg/pr71104-2.c

+/* { dg-do compile } */
+
+struct Foo { char c[1024]; };
+void foo(void);
+struct Foo baz(void) __attribute__((returns_twice));
+struct Foo *p;
+
+void bar(void)
+{
+  foo();
+  *p = baz();
+}