Correct storage size assignment for variables

The implementation of global and local variables using BPF maps added calls to dt_ident_set_storage() to set the offset and size of the data storage for each variable. It was setting the storage requirement for any automatically declared variable to 8 bytes regardless of its type. Since the datatype of such a variable is determined dynamically based on its use, the storage assignment must be done once the datatype is known. But by then, some code was already generated based on the wrong size. Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com> Reviewed-by: Eugene Loh <eugene.loh@oracle.com>
oracle · Jun 18, 2021 · 9a4c70e · 9a4c70e
1 parent 6437db5
commit 9a4c70e
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Showing 3 changed files with 61 additions and 7 deletions.
diff --git a/libdtrace/dt_parser.c b/libdtrace/dt_parser.c
@@ -1661,10 +1661,10 @@ dt_node_decl(void)
 			if (idp == NULL)
 				longjmp(yypcb->pcb_jmpbuf, EDT_NOMEM);
 
-			dt_ident_set_storage(idp, 8,
-					     ctf_type_size(dtt.dtt_ctfp, type));
-
 			dt_ident_type_assign(idp, dtt.dtt_ctfp, dtt.dtt_type);
+			dt_ident_set_storage(idp, 8,
+					     ctf_type_size(dtt.dtt_ctfp,
+							   dtt.dtt_type));
 
 			/*
 			 * If we are declaring an associative array, use our
@@ -2754,10 +2754,6 @@ dt_xcook_ident(dt_node_t *dnp, dt_idhash_t *dhp, uint_t idkind, int create)
 		if (idp == NULL)
 			longjmp(yypcb->pcb_jmpbuf, EDT_NOMEM);
 
-		/* aggregation storage size is set later, in dt_cg.c */
-		if (idkind != DT_IDENT_AGG)
-			dt_ident_set_storage(idp, 8, 8);
-
 		/*
 		 * Arrays and aggregations are not cooked individually. They
 		 * have dynamic types and must be referenced using operator [].
@@ -2871,6 +2867,8 @@ dt_cook_op1(dt_node_t *dnp, uint_t idflags)
 			xyerror(D_TYPE_ERR, "failed to lookup int64_t\n");
 
 		dt_ident_type_assign(cp->dn_ident, dtt.dtt_ctfp, dtt.dtt_type);
+		dt_ident_set_storage(cp->dn_ident, 8,
+				     ctf_type_size(dtt.dtt_ctfp, dtt.dtt_type));
 		dt_node_type_assign(cp, dtt.dtt_ctfp, dtt.dtt_type);
 	}
 
@@ -3485,6 +3483,8 @@ dt_cook_op2(dt_node_t *dnp, uint_t idflags)
 		    dt_ident_unref(lp->dn_ident)) {
 			dt_node_type_assign(lp, ctfp, type);
 			dt_ident_type_assign(lp->dn_ident, ctfp, type);
+			dt_ident_set_storage(lp->dn_ident, 8,
+					     ctf_type_size(ctfp, type));
 
 			if (uref) {
 				lp->dn_flags |= DT_NF_USERLAND;

diff --git a/test/unittest/variables/gvar/tst.undecl-offset.r b/test/unittest/variables/gvar/tst.undecl-offset.r
@@ -0,0 +1,3 @@
+NAME             OFFSET KND SCP FLAG TYPE
+a                0      scl glb r/w  string (unknown) by ref (size 256)
+b                100    scl glb w    string (unknown) by ref (size 256)
diff --git a/test/unittest/variables/gvar/tst.undecl-offset.sh b/test/unittest/variables/gvar/tst.undecl-offset.sh
@@ -0,0 +1,51 @@
+#!/bin/bash
+#
+# Oracle Linux DTrace.
+# Copyright (c) 2021, 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: Storage size of undeclared variables is based on their discovered
+#            datatype
+#
+# SECTION: Variables/Scalar Variables
+#
+##
+
+dtrace=$1
+
+$dtrace $dt_flags -Sen '
+BEGIN
+{
+	a = "";
+	b = a;
+	exit(0);
+}
+' 2>&1 | awk '
+BEGIN {
+	rc = 1;
+}
+
+/^NAME/ && /KND SCP/ {
+	printf "%-16s %-6s %-3s %-3s %-4s %s\n",
+	       "NAME", "OFFSET", "KND", "SCP","FLAG", "TYPE";
+	while (getline == 1 && NF > 0) {
+		$2 = $6 = "";
+		gsub(/ +/, " ");
+		printf "%-16s %-6s %-3s %-3s %-4s", $1, $2, $3, $4, $5;
+		$1 = $2 = $3 = $4 = $5 = "";
+		gsub(/ +/, " ");
+		print $0;
+		rc = 0;
+	}
+}
+
+END {
+	exit(rc);
+}
+'
+
+exit $?