Restore order of bcopy() arg evaluations

In c26e2e5 ("Add support for copyinto() subroutine"), the order
of arg evaluations for bcopy() was changed from evaluating the last
arg (size) last to evaluating it first.  This has semantic implications
when the order of arguments matters.

Restore the previous order (to agree with Solaris semantics) and add
tests for both bcopy() and copyinto().

Signed-off-by: Eugene Loh <eugene.loh@oracle.com>
Reviewed-by: Kris Van Hees <kris.van.hees@oracle.com>

libdtrace/dt_cg.c

@@ -4523,18 +4523,25 @@ dt_cg_subr_bcopy_impl(dt_node_t *dnp, dt_node_t *dst, dt_node_t *src,
 
 	TRACE_REGSET("      subr-bcopy-impl:Begin");
 
-	/* Validate the size for the copy operation. */
-	dt_cg_node(size, dlp, drp);
+	/* Evaluate the arguments */
+	if (is_bcopy) {
+		dt_cg_node(src, dlp, drp);
+		dt_cg_node(dst, dlp, drp);
+		dt_cg_node(size, dlp, drp);
+	} else {
+		dt_cg_node(src, dlp, drp);
+		dt_cg_node(size, dlp, drp);
+		dt_cg_node(dst, dlp, drp);
+	}
 
+	/* Validate the size for the copy operation. */
 	emit(dlp,  BPF_BRANCH_IMM(BPF_JSLT, size->dn_reg, 0, lbl_badsize));
 	emit(dlp,  BPF_BRANCH_IMM(BPF_JGT, size->dn_reg, maxsize, lbl_badsize));
 
 	/* Validate the source pointer. */
-	dt_cg_node(src, dlp, drp);
 	dt_cg_check_ptr_arg(dlp, drp, src, size);
 
 	/* Validate the destination pointer. */
-	dt_cg_node(dst, dlp, drp);
 	if (!(dst->dn_flags & DT_NF_ALLOCA))
 		dnerror(dst, D_PROTO_ARG,
 			"%s( ) argument #%d is incompatible with prototype:\n"

test/unittest/funcs/bcopy/tst.bcopy_arg_order.d

@@ -0,0 +1,52 @@
+/*
+ * Oracle Linux DTrace.
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * Licensed under the Universal Permissive License v 1.0 as shown at
+ * http://oss.oracle.com/licenses/upl.
+ */
+
+/*
+ * ASSERTION: Arguments are evaluated in the correct order.
+ *
+ * SECTION: Actions and Subroutines/bcopy()
+ */
+
+#pragma D option quiet
+
+BEGIN
+{
+	src = (char *)alloca(8);
+	dst = (char *)alloca(8);
+
+	/* initialize src */
+	src[ 0] = 'a'; src[ 1] = 'b'; src[ 2] = 'c'; src[ 3] = 'd';
+	src[ 4] = 'e'; src[ 5] = 'f'; src[ 6] = 'g'; src[ 7] = 'h';
+
+	/* initialize dst with '.' */
+	dst[ 0] = dst[ 1] = dst[ 2] = dst[ 3] =
+	dst[ 4] = dst[ 5] = dst[ 6] = dst[ 7] = '.';
+
+	/* execute subroutine with order-dependent arguments */
+	n = 2;
+	bcopy((void*)(src + (n++)), (void*)(dst + (n++)), (n++));
+
+	/* print results */
+	printf("%c%c%c%c%c%c%c%c\n",
+	    dst[ 0], dst[ 1], dst[ 2], dst[ 3],
+	    dst[ 4], dst[ 5], dst[ 6], dst[ 7]);
+
+	/* repeat all that but with order-independent arguments */
+	dst[ 0] = dst[ 1] = dst[ 2] = dst[ 3] =
+	dst[ 4] = dst[ 5] = dst[ 6] = dst[ 7] = '.';
+	bcopy((void*)(src + 2), (void*)(dst + 3), 4);
+	printf("%c%c%c%c%c%c%c%c\n",
+	    dst[ 0], dst[ 1], dst[ 2], dst[ 3],
+	    dst[ 4], dst[ 5], dst[ 6], dst[ 7]);
+
+	exit(0);
+}
+
+ERROR
+{
+	exit(1);
+}

test/unittest/funcs/bcopy/tst.bcopy_arg_order.r

@@ -0,0 +1,3 @@
+...cdef.
+...cdef.
+

test/unittest/funcs/copyinto/tst.copyinto_arg_order.d

@@ -0,0 +1,57 @@
+/*
+ * Oracle Linux DTrace.
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * Licensed under the Universal Permissive License v 1.0 as shown at
+ * http://oss.oracle.com/licenses/upl.
+ */
+
+/*
+ * ASSERTION: Arguments are evaluated in the correct order.
+ *
+ * SECTION: Actions and Subroutines/copyinto()
+ */
+/* @@trigger: delaydie */
+
+#pragma D option quiet
+
+syscall::write:entry
+/pid == $target/
+{
+	ptr = (char *)alloca(16);
+
+	/* initialize with '.' */
+	ptr[ 0] = ptr[ 1] = ptr[ 2] = ptr[ 3] =
+	ptr[ 4] = ptr[ 5] = ptr[ 6] = ptr[ 7] =
+	ptr[ 8] = ptr[ 9] = ptr[10] = ptr[11] =
+	ptr[12] = ptr[13] = ptr[14] = ptr[15] = '.';
+
+	/* execute subroutine with order-dependent arguments */
+	n = 2;
+	copyinto(arg1 + (n++), (n++), (void*)(ptr + (n++)));
+
+	/* print results */
+	printf("%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c\n",
+	    ptr[ 0], ptr[ 1], ptr[ 2], ptr[ 3],
+	    ptr[ 4], ptr[ 5], ptr[ 6], ptr[ 7],
+	    ptr[ 8], ptr[ 9], ptr[10], ptr[11],
+	    ptr[12], ptr[13], ptr[14], ptr[15]);
+
+	/* repeat all that but with order-independent arguments */
+	ptr[ 0] = ptr[ 1] = ptr[ 2] = ptr[ 3] =
+	ptr[ 4] = ptr[ 5] = ptr[ 6] = ptr[ 7] =
+	ptr[ 8] = ptr[ 9] = ptr[10] = ptr[11] =
+	ptr[12] = ptr[13] = ptr[14] = ptr[15] = '.';
+	copyinto(arg1 + 2, 3, (void *)(ptr + 4));
+	printf("%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c\n",
+	    ptr[ 0], ptr[ 1], ptr[ 2], ptr[ 3],
+	    ptr[ 4], ptr[ 5], ptr[ 6], ptr[ 7],
+	    ptr[ 8], ptr[ 9], ptr[10], ptr[11],
+	    ptr[12], ptr[13], ptr[14], ptr[15]);
+
+	exit(0);
+}
+
+ERROR
+{
+	exit(1);
+}

test/unittest/funcs/copyinto/tst.copyinto_arg_order.r

@@ -0,0 +1,5 @@
+....lay.........
+....lay.........
+
+-- @@stderr --
+Delay in ns needed in delay env var.