code review 7845043: runtime: remove struct BitTarget (issue 7845043)

[0xE2.0x...@gmail.com]

Reviewers: golang-dev1,

Message:
Hello golan...@googlegroups.com (cc: rsc, dvyukov),

I'd like you to review this change to
https://code.google.com/p/go/


Description:
runtime: remove struct BitTarget

Please review this at https://codereview.appspot.com/7845043/

Affected files:
M src/pkg/runtime/mgc0.c


Index: src/pkg/runtime/mgc0.c
===================================================================
--- a/src/pkg/runtime/mgc0.c
+++ b/src/pkg/runtime/mgc0.c
@@ -270,7 +270,7 @@
return true;
}

-// PtrTarget and BitTarget are structures used by intermediate buffers.
+// PtrTarget is a structure used by intermediate buffers.
// The intermediate buffers hold GC data before it
// is moved/flushed to the work buffer (Workbuf).
// The size of an intermediate buffer is very small,
@@ -282,19 +282,10 @@
uintptr ti;
};

-typedef struct BitTarget BitTarget;
-struct BitTarget
-{
- void *p;
- uintptr ti;
- uintptr *bitp, shift;
-};
-
typedef struct BufferList BufferList;
struct BufferList
{
PtrTarget ptrtarget[IntermediateBufferCapacity];
- BitTarget bittarget[IntermediateBufferCapacity];
Obj obj[IntermediateBufferCapacity];
BufferList *next;
};
@@ -311,7 +302,6 @@
// and are prepared to be scanned by the garbage collector.
//
// _wp, _wbuf, _nobj are input/output parameters and are specifying the
work buffer.
-// bitbuf holds temporary data generated by this function.
//
// A simplified drawing explaining how the todo-list moves from a
structure to another:
//
@@ -319,14 +309,12 @@
// (find pointers)
// Obj ------> PtrTarget (pointer targets)
// ↑ |
-// | | flushptrbuf (1st part,
-// | | find block start)
-// | ↓
-// `--------- BitTarget (pointer targets and the corresponding
locations in bitmap)
-// flushptrbuf
-// (2nd part, mark and enqueue)
+// | |
+// `----------'
+// flushptrbuf
+// (find block start, mark and enqueue)
static void
-flushptrbuf(PtrTarget *ptrbuf, PtrTarget **ptrbufpos, Obj **_wp, Workbuf
**_wbuf, uintptr *_nobj, BitTarget *bitbuf)
+flushptrbuf(PtrTarget *ptrbuf, PtrTarget **ptrbufpos, Obj **_wp, Workbuf
**_wbuf, uintptr *_nobj)
{
byte *p, *arena_start, *obj;
uintptr size, *bitp, bits, shift, j, x, xbits, off, nobj, ti, n;
@@ -585,7 +573,6 @@
Frame *stack_ptr, stack_top, stack[GC_STACK_CAPACITY+4];
BufferList *scanbuffers;
PtrTarget *ptrbuf, *ptrbuf_end, *ptrbufpos;
- BitTarget *bitbuf;
Obj *objbuf, *objbuf_end, *objbufpos;
Eface *eface;
Iface *iface;
@@ -609,7 +596,7 @@
precise_type = false;
nominal_size = 0;

- // Allocate ptrbuf, bitbuf
+ // Allocate ptrbuf
{
runtime·lock(&lock);

@@ -624,7 +611,6 @@

ptrbuf = &scanbuffers->ptrtarget[0];
ptrbuf_end = &scanbuffers->ptrtarget[0] + nelem(scanbuffers->ptrtarget);
- bitbuf = &scanbuffers->bittarget[0];
objbuf = &scanbuffers->obj[0];
objbuf_end = &scanbuffers->obj[0] + nelem(scanbuffers->obj);

@@ -794,7 +780,7 @@
if((void*)iface->tab >= arena_start && (void*)iface->tab < arena_used) {
*ptrbufpos++ = (PtrTarget){iface->tab, (uintptr)itabtype->gc};
if(ptrbufpos == ptrbuf_end)
- flushptrbuf(ptrbuf, &ptrbufpos, &wp, &wbuf, &nobj, bitbuf);
+ flushptrbuf(ptrbuf, &ptrbufpos, &wp, &wbuf, &nobj);
}

// iface->data
@@ -821,7 +807,7 @@
if(obj >= arena_start && obj < arena_used) {
*ptrbufpos++ = (PtrTarget){obj, 0};
if(ptrbufpos == ptrbuf_end)
- flushptrbuf(ptrbuf, &ptrbufpos, &wp, &wbuf, &nobj, bitbuf);
+ flushptrbuf(ptrbuf, &ptrbufpos, &wp, &wbuf, &nobj);
}
}
goto next_block;
@@ -923,7 +909,7 @@
while(hash_gciter_next(&map_iter, &d)) {
// buffers: reserve space for 2 objects.
if(ptrbufpos+2 >= ptrbuf_end)
- flushptrbuf(ptrbuf, &ptrbufpos, &wp, &wbuf, &nobj, bitbuf);
+ flushptrbuf(ptrbuf, &ptrbufpos, &wp, &wbuf, &nobj);
if(objbufpos+2 >= objbuf_end)
flushobjbuf(objbuf, &objbufpos, &wp, &wbuf, &nobj);

@@ -989,7 +975,7 @@
if(obj >= arena_start && obj < arena_used) {
*ptrbufpos++ = (PtrTarget){obj, objti};
if(ptrbufpos == ptrbuf_end)
- flushptrbuf(ptrbuf, &ptrbufpos, &wp, &wbuf, &nobj, bitbuf);
+ flushptrbuf(ptrbuf, &ptrbufpos, &wp, &wbuf, &nobj);
}
}

@@ -998,7 +984,7 @@
// the loop by setting b, n, ti to the parameters for the next block.

if(nobj == 0) {
- flushptrbuf(ptrbuf, &ptrbufpos, &wp, &wbuf, &nobj, bitbuf);
+ flushptrbuf(ptrbuf, &ptrbufpos, &wp, &wbuf, &nobj);
flushobjbuf(objbuf, &objbufpos, &wp, &wbuf, &nobj);

if(nobj == 0) {

[Russ Cox]

LGTM

[r...@golang.org]

*** Submitted as
https://code.google.com/p/go/source/detail?r=821f6f552e3d ***

runtime: remove struct BitTarget

R=golang-dev
CC=dvyukov, golang-dev, rsc
https://codereview.appspot.com/7845043

Committer: Russ Cox <r...@golang.org>


https://codereview.appspot.com/7845043/