From 5a2d1fb4db65d847d5bc9ea1cf5192bd81d8c7e5 Mon Sep 17 00:00:00 2001
From: Justus Winter <4winter@informatik.uni-hamburg.de>
Date: Mon, 1 Dec 2014 17:13:34 +0100
Subject: Add static branch prediction to type checks

Annotate generated type checks with static branch prediction
optimizing well-formed messages.

* utils.c (WriteBogusDefines): Define `mig_unlikely' if not defined.
* server.c: Use `mig_unlikely' in generated type checks.
* user.c: Likewise.
---
 utils.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

(limited to 'utils.c')

diff --git a/utils.c b/utils.c
index 6c42bc3..396e743 100644
--- a/utils.c
+++ b/utils.c
@@ -60,6 +60,11 @@ WriteBogusDefines(FILE *file)
     fprintf(file, "#endif\n");
     fprintf(file, "\n");
 
+    fprintf(file, "#ifndef\tmig_unlikely\n");
+    fprintf(file, "#define\tmig_unlikely(X)\t__builtin_expect (!! (X), 0)\n");
+    fprintf(file, "#endif\n");
+    fprintf(file, "\n");
+
     fprintf(file, "#ifndef\tTypeCheck\n");
     fprintf(file, "#define\tTypeCheck 1\n");
     fprintf(file, "#endif\n");
@@ -70,11 +75,11 @@ WriteBogusDefines(FILE *file)
     fprintf(file, "#endif\n");
     fprintf(file, "\n");
 
-    fprintf(file, "#define BAD_TYPECHECK(type, check) ({\\\n");
+    fprintf(file, "#define BAD_TYPECHECK(type, check) mig_unlikely (({\\\n");
     fprintf(file,
 	    "  union { mach_msg_type_t t; unsigned32_t w; } _t, _c;\\\n");
     fprintf(file,
-	    "  _t.t = *(type); _c.t = *(check); _t.w != _c.w; })\n");
+	    "  _t.t = *(type); _c.t = *(check);_t.w != _c.w; }))\n");
 }
 
 void
-- 
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