2004-04-02 Jakub Jelinek <jakuB@redhat.com>

	    Eric Botcazou  <ebotcazou@libertysurf.fr>

	PR optimization/13424, optimization/12419
	* explow.c (maybe_set_unchanging): Revert 2003-04-07 patch.
	* expr.c (store_constructor): When clearing aggregate because
	of an incomplete or mostly zero constructor, do the clearing
	without /u flag and then emit a blockage.

	* gcc.dg/20040302-1.c: New test.
	* gcc.c-torture/execute/20040401-1.c: New test.

2003-04-08  Glen Nakamura  <glen@imodulo.com>

	* gcc.c-torture/execute/20030408-1.c: New test.


git-svn-id: https://gcc.gnu.org/svn/gcc/branches/gcc-3_3-rhl-branch@80655 138bc75d-0d04-0410-961f-82ee72b054a4

6 files changed, 148 insertions, 6 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6afe21761fe..d3e0d8bd1dc 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2004-04-02  Jakub Jelinek  <jakuB@redhat.com>
+	    Eric Botcazou  <ebotcazou@libertysurf.fr>
+
+	PR optimization/13424, optimization/12419
+	* explow.c (maybe_set_unchanging): Revert 2003-04-07 patch.
+	* expr.c (store_constructor): When clearing aggregate because
+	of an incomplete or mostly zero constructor, do the clearing
+	without /u flag and then emit a blockage.
+
 2004-03-27  Jakub Jelinek  <jakub@redhat.com>
 
 	* config/i386/i386.c (override_options): Add PTA_64BIT, set it
diff --git a/gcc/explow.c b/gcc/explow.c
index c66a8e765bf..bef4f90b1b4 100644
--- a/gcc/explow.c
+++ b/gcc/explow.c
@@ -673,7 +673,6 @@ maybe_set_unchanging (ref, t)
      solution, perhaps based on alias sets.  */
 
   if ((TREE_READONLY (t) && DECL_P (t)
-       && (TREE_STATIC (t) || ! AGGREGATE_TYPE_P (TREE_TYPE (t)))
        && (TREE_CODE (t) == PARM_DECL
 	   || DECL_INITIAL (t) == NULL_TREE
 	   || TREE_CONSTANT (DECL_INITIAL (t))))
diff --git a/gcc/expr.c b/gcc/expr.c
index fa3d10ea2d7..c31eba65542 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -5021,14 +5021,27 @@ store_constructor (exp, target, cleared, size)
 	{
 	  rtx xtarget = target;
 
-	  if (readonly_fields_p (type))
+	  if (RTX_UNCHANGING_P (target))
 	    {
-	      xtarget = copy_rtx (xtarget);
-	      RTX_UNCHANGING_P (xtarget) = 1;
+	      xtarget = copy_rtx (target);
+	      RTX_UNCHANGING_P (xtarget) = 0;
 	    }
 
 	  clear_storage (xtarget, GEN_INT (size));
 	  cleared = 1;
+	  if (RTX_UNCHANGING_P (target) || readonly_fields_p (type))
+	    {
+	      /* ??? Emit a blockage to prevent the scheduler from swapping
+		 the memory write issued above without the /u flag and
+		 memory writes that will be issued later with it.
+		 Note that the clearing above cannot be simply disabled
+		 in the unsafe cases because the C front-end relies on
+		 it to implement the semantics of constructors for
+		 automatic objects.  However, not all machine descriptions
+		 define a blockage insn, so emit an ASM_INPUT to
+		 act as one.  */
+	      emit_insn (gen_rtx_ASM_INPUT (VOIDmode, ""));
+	    }
 	}
 
       if (! cleared)
@@ -5242,9 +5255,28 @@ store_constructor (exp, target, cleared, size)
 	  if (! cleared)
 	    {
 	      if (REG_P (target))
-		emit_move_insn (target,  CONST0_RTX (GET_MODE (target)));
+		emit_move_insn (target, CONST0_RTX (GET_MODE (target)));
 	      else
-		clear_storage (target, GEN_INT (size));
+		{
+		  rtx xtarget = target;
+
+		  if (RTX_UNCHANGING_P (target))
+		    {
+		      xtarget = copy_rtx (target);
+		      RTX_UNCHANGING_P (xtarget) = 0;
+		    }
+
+		  clear_storage (xtarget, GEN_INT (size));
+
+		  if (RTX_UNCHANGING_P (target))
+		    {
+		      /* ??? Emit a blockage to prevent the scheduler from
+			 swapping the memory write issued above without the
+			 /u flag and memory writes that will be issued later
+			 with it.  */
+		      emit_insn (gen_rtx_ASM_INPUT (VOIDmode, ""));
+		    }
+		}
 	    }
 	  cleared = 1;
 	}
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 18a65adae17..a80e7d49f8b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,13 @@
+2004-04-02  Jakub Jelinek  <jakuB@redhat.com>
+	    Eric Botcazou  <ebotcazou@libertysurf.fr>
+
+	* gcc.dg/20040302-1.c: New test.
+	* gcc.c-torture/execute/20040401-1.c: New test.
+
+2003-04-08  Glen Nakamura  <glen@imodulo.com>
+
+	* gcc.c-torture/execute/20030408-1.c: New test.
+
 2004-04-01  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/14755
diff --git a/gcc/testsuite/gcc.c-torture/execute/20040401-1.c b/gcc/testsuite/gcc.c-torture/execute/20040401-1.c
new file mode 100644
index 00000000000..d74afda4707
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/20040401-1.c
@@ -0,0 +1,74 @@
+/* PR optimization/8634 */
+
+extern void abort (void);
+
+struct foo {
+  const char a, b, c, d, e, f, g, h, i, j;
+};
+
+struct bar {
+  const char a, b, c, d, e, f, g, h, i;
+  char j;
+};
+
+int test1 ()
+{
+  struct foo X = { a : 'A', c : 'C', e : 'E', g : 'G', i : 'I' };
+  char buffer[10];
+  __builtin_memcpy (buffer, &X, 10);
+  if (buffer[0] != 'A' || buffer[1] != '\0'
+      || buffer[2] != 'C' || buffer[3] != '\0'
+      || buffer[4] != 'E' || buffer[5] != '\0'
+      || buffer[6] != 'G' || buffer[7] != '\0'
+      || buffer[8] != 'I' || buffer[9] != '\0')
+    abort ();
+  return 0;
+}
+
+int test2 ()
+{
+  struct bar X = { a : 'A', c : 'C', e : 'E', g : 'G', i : 'I' };
+  char buffer[10];
+  __builtin_memcpy (buffer, &X, 10);
+  if (buffer[0] != 'A' || buffer[1] != '\0'
+      || buffer[2] != 'C' || buffer[3] != '\0'
+      || buffer[4] != 'E' || buffer[5] != '\0'
+      || buffer[6] != 'G' || buffer[7] != '\0'
+      || buffer[8] != 'I' || buffer[9] != '\0')
+    abort ();
+  return 0;
+}
+
+int test3 ()
+{
+  struct foo X = { .b = 'B', .d = 'D', .f = 'F', .h = 'H' , .j = 'J' };
+  char buffer[10];
+  __builtin_memcpy (buffer, &X, 10);
+  if (buffer[0] != '\0' || buffer[1] != 'B'
+      || buffer[2] != '\0' || buffer[3] != 'D'
+      || buffer[4] != '\0' || buffer[5] != 'F'
+      || buffer[6] != '\0' || buffer[7] != 'H'
+      || buffer[8] != '\0' || buffer[9] != 'J')
+    abort ();
+  return 0;
+}
+
+int test4 ()
+{
+  struct bar X = { .b = 'B', .d = 'D', .f = 'F', .h = 'H' , .j = 'J' };
+  char buffer[10];
+  __builtin_memcpy (buffer, &X, 10);
+  if (buffer[0] != '\0' || buffer[1] != 'B'
+      || buffer[2] != '\0' || buffer[3] != 'D'
+      || buffer[4] != '\0' || buffer[5] != 'F'
+      || buffer[6] != '\0' || buffer[7] != 'H'
+      || buffer[8] != '\0' || buffer[9] != 'J')
+    abort ();
+  return 0;
+}
+
+int main ()
+{
+  test1 (); test2 (); test3 (); test4 ();
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/20040302-1.c b/gcc/testsuite/gcc.dg/20040302-1.c
new file mode 100644
index 00000000000..f6ada1f22c2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/20040302-1.c
@@ -0,0 +1,18 @@
+/* PR optimization/12419 */
+/* Ensure external_const_array[0] is read just once.  */
+/* { dg-do compile { target i?86-*-linux* x86_64-*-linux* } } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler "external_const_array" } } */
+/* { dg-final { scan-assembler-not "external_const_array.*add\[^\\n\]*external_const_array" } } */
+
+extern const int external_const_array [];
+extern void foo (void);
+
+int
+bar (void)
+{
+  int n = external_const_array[0];
+  foo ();
+  n += external_const_array[0];
+  return n;
+}