[Issue 3454] New: Inconsistent flag setting in GC.realloc()
d-bugmail at puremagic.com
d-bugmail at puremagic.com
Thu Oct 29 17:26:45 PDT 2009
http://d.puremagic.com/issues/show_bug.cgi?id=3454
Summary: Inconsistent flag setting in GC.realloc()
Product: D
Version: 2.035
Platform: Other
OS/Version: Windows
Status: NEW
Severity: normal
Priority: P2
Component: druntime
AssignedTo: sean at invisibleduck.org
ReportedBy: dsimcha at yahoo.com
--- Comment #0 from David Simcha <dsimcha at yahoo.com> 2009-10-29 17:26:42 PDT ---
GC.realloc() doesn't set the flags on either the old or new memory block for a
whole bunch of code paths. I was tipped off to this by reading the code while
trying to add precise heap scanning. Here's a test program that demonstrates
this.
import std.stdio, core.memory;
void main() {
doTest(1);
writeln();
doTest(1024 * 1024);
}
void doTest(size_t multiplier) {
auto foo = GC.malloc(8 * multiplier);
auto bar = GC.realloc(foo, 2 * multiplier, GC.BlkAttr.NO_SCAN);
writeln("Old block attributes: ", GC.getAttr(foo));
writeln("New block attributes: ", GC.getAttr(bar));
writeln("Old Ptr: ", foo, " New Ptr: ", bar);
}
Output:
Old block attributes: 2
New block attributes: 2
Old Ptr: 961E40 New Ptr: 961E30
Old block attributes: 0
New block attributes: 0
Old Ptr: 10C0000 New Ptr: 10C0000
This is caused by the GC returning early from the B_PAGE path, or if the new
block is almost the same size as the old block. If I get precise heap scanning
to work, I'll include a fix for this in the patch.
--
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
More information about the Digitalmars-d-bugs
mailing list