[pypy-commit] stmgc use-gcc: Avoid 'uint8_t' as fields because gcc considers that read/writes to it

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: use-gcc
Changeset: r1764:c87e955695ac
Date: 2015-05-23 23:08 +0200
http://bitbucket.org/pypy/stmgc/changeset/c87e955695ac/

Log:	Avoid 'uint8_t' as fields because gcc considers that read/writes to
	it are like read/writes to a 'char *' pointer and can alias
	anything. Instead, ':8' integers are equivalent but without the
	aliasing problem.

diff --git a/c7/stmgc.h b/c7/stmgc.h
--- a/c7/stmgc.h
+++ b/c7/stmgc.h
@@ -38,11 +38,11 @@
        'STM_SEGMENT->transaction_read_version' if and only if the
        object was read in the current transaction.  The nurseries
        also have corresponding read markers, but they are never used. */
-    uint8_t rm;
+    unsigned rm:8;
 };
 
 struct stm_segment_info_s {
-    uint8_t transaction_read_version;
+    unsigned int transaction_read_version;
     int segment_num;
     char *segment_base;
     stm_char *nursery_current;