diff mbox

Fix PR78472

Message ID alpine.LSU.2.11.1611221625410.5294@t29.fhfr.qr
State New
Headers show

Commit Message

Richard Biener Nov. 22, 2016, 3:26 p.m. UTC 
The following fixes a C/C++ interoperability issue with LTO when
zero-sized fields appear in one variant of a struct but not in another.

Bootstrap & regtest in progress on x86_64-unknown-linux-gnu.

Richard.

2016-11-22  Richard Biener  <rguenther@suse.de>

	PR lto/78472
	* tree.c (gimple_canonical_types_compatible_p): Ignore zero-sized
	fields.

	lto/
	* lto.c (hash_canonical_type): Ignore zero-sized fields.

	* g++.dg/lto/pr78472_0.c: New testcase.
	* g++.dg/lto/pr78472_1.C: Likewise.
diff mbox

Patch

Index: gcc/tree.c
===================================================================
--- gcc/tree.c	(revision 242657)
+++ gcc/tree.c	(working copy)
@@ -13506,10 +13506,12 @@  gimple_canonical_types_compatible_p (con
 	     f1 || f2;
 	     f1 = TREE_CHAIN (f1), f2 = TREE_CHAIN (f2))
 	  {
-	    /* Skip non-fields.  */
-	    while (f1 && TREE_CODE (f1) != FIELD_DECL)
+	    /* Skip non-fields and zero-sized fields.  */
+	    while (f1 && (TREE_CODE (f1) != FIELD_DECL
+			  || integer_zerop (DECL_SIZE (f1))))
 	      f1 = TREE_CHAIN (f1);
-	    while (f2 && TREE_CODE (f2) != FIELD_DECL)
+	    while (f2 && (TREE_CODE (f2) != FIELD_DECL
+			  || integer_zerop (DECL_SIZE (f2))))
 	      f2 = TREE_CHAIN (f2);
 	    if (!f1 || !f2)
 	      break;
Index: gcc/lto/lto.c
===================================================================
--- gcc/lto/lto.c	(revision 242657)
+++ gcc/lto/lto.c	(working copy)
@@ -372,7 +372,8 @@  hash_canonical_type (tree type)
       tree f;
 
       for (f = TYPE_FIELDS (type), nf = 0; f; f = TREE_CHAIN (f))
-	if (TREE_CODE (f) == FIELD_DECL)
+	if (TREE_CODE (f) == FIELD_DECL
+	    && ! integer_zerop (DECL_SIZE (f)))
 	  {
 	    iterative_hash_canonical_type (TREE_TYPE (f), hstate);
 	    nf++;
Index: gcc/testsuite/g++.dg/lto/pr78472_0.c
===================================================================
--- gcc/testsuite/g++.dg/lto/pr78472_0.c	(revision 0)
+++ gcc/testsuite/g++.dg/lto/pr78472_0.c	(working copy)
@@ -0,0 +1,12 @@ 
+// { dg-lto-do link }
+
+extern struct S
+{
+  unsigned i:4;
+  unsigned :0;
+} s;
+static void *f(void)
+{
+  return &s;
+}
+int main() {}
Index: gcc/testsuite/g++.dg/lto/pr78472_1.C
===================================================================
--- gcc/testsuite/g++.dg/lto/pr78472_1.C	(revision 0)
+++ gcc/testsuite/g++.dg/lto/pr78472_1.C	(working copy)
@@ -0,0 +1,9 @@ 
+struct S
+{
+  unsigned i:4;
+  unsigned :0;
+} s;
+static void *f(void)
+{
+  return &s;
+}