From 44753cf5a30b9324d2c4ac9021843674bde5cc3c Mon Sep 17 00:00:00 2001
From: Justus Winter <4winter@informatik.uni-hamburg.de>
Date: Sun, 15 Feb 2015 13:29:30 +0100
Subject: Do not generate code dereferencing type-punned pointers

For variable-length arrays, up to 2048 bytes are transmitted inline.
If the array is larger, the data is transmitted out-of-line, and a
pointer to a vm_allocated region is stored at the beginning of the
array.

Previously, the generated code casted the field.  Use a union instead.

This fixes the gcc warning `dereferencing type-punned pointer will
break strict-aliasing rules [-Wstrict-aliasing]'.

* global.c (OOLPostfix): New variable.
* global.h (OOLPostfix): New declaration.
* server.c (WriteServerCallArg): Avoid cast.
(WriteDestroyArg): Likewise.
(WritePackArgValue): Likewise.
(WritePackArg): Likewise.
* user.c (WriteExtractArgValue): Likewise.
* utils.c (WriteFieldDeclPrim): Generate a union with an additional
pointer field for variable-length arrays.
---
 server.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

(limited to 'server.c')

diff --git a/server.c b/server.c
index 56ccfc7..15fc128 100644
--- a/server.c
+++ b/server.c
@@ -777,9 +777,9 @@ WriteServerCallArg(FILE *file, const argument_t *arg)
 		    arg->argTTName,
 		    arg->argLongForm ? ".msgtl_header" : "");
 	    fprintf(file, "? %s ", InArgMsgField(arg));
-	    fprintf(file, ": *((%s **)%s)",
-			FetchServerType(arg->argType->itElement),
-			InArgMsgField(arg));
+	    fprintf(file, ": %s%s",
+		    InArgMsgField(arg),
+		    OOLPostfix);
 	}
 	else
 	    fprintf(file, "%s", InArgMsgField(arg));
@@ -816,8 +816,8 @@ WriteDestroyArg(FILE *file, const argument_t *arg)
 		arg->argRequestPos,
 		arg->argTTName,
 		arg->argLongForm ? ".msgtl_header" : "");
-	fprintf(file, "\t\t\t%smig_deallocate(* (vm_offset_t *) %s, ",
-		SubrPrefix, InArgMsgField(arg));
+	fprintf(file, "\t\t\t%smig_deallocate((vm_offset_t) %s%s, ",
+		SubrPrefix, InArgMsgField(arg), OOLPostfix);
 	if (multiplier > 1)
 	    fprintf(file, "%d * ", multiplier);
 	fprintf(file, " %s);\n", InArgMsgField(count));
@@ -978,9 +978,9 @@ WritePackArgValue(FILE *file, const argument_t *arg)
 			    arg->argTTName,
 			    arg->argLongForm ? ".msgtl_header" : "",
 			    arg->argDealloc->argVarName);
-		fprintf(file, "\t\t*((%s **)OutP->%s) = %sP;\n",
-			FetchServerType(btype),
+		fprintf(file, "\t\tOutP->%s%s = %sP;\n",
 			arg->argMsgField,
+			OOLPostfix,
 			arg->argVarName);
 		if (!arg->argRoutine->rtSimpleFixedReply)
 		    fprintf(file, "\t\tmsgh_simple = FALSE;\n");
@@ -1203,9 +1203,9 @@ WritePackArg(FILE *file, const argument_t *arg)
 			arg->argTTName,
 			arg->argLongForm ? ".msgtl_header" : "",
 			arg->argDealloc->argVarName);
-	    fprintf(file, "\t\t*((%s **)OutP->%s) = %sP;\n",
-			FetchServerType(it->itElement),
+	    fprintf(file, "\t\tOutP->%s%s = %sP;\n",
 			arg->argMsgField,
+			OOLPostfix,
 			arg->argVarName);
 	    if (!arg->argRoutine->rtSimpleFixedReply)
 		fprintf(file, "\t\tmsgh_simple = FALSE;\n");
-- 
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