D.gnu - [Issue 2584] New: GDC on ARM does not honor volatile
- d-bugmail puremagic.com (26/26) Jan 13 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2584
- d-bugmail puremagic.com (4/4) Jan 13 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2584
- d-bugmail puremagic.com (22/22) Jan 13 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2584
- d-bugmail puremagic.com (12/12) Oct 09 2012 http://d.puremagic.com/issues/show_bug.cgi?id=2584
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- d-bugmail puremagic.com (9/13) Oct 10 2012 http://d.puremagic.com/issues/show_bug.cgi?id=2584
- d-bugmail puremagic.com (34/34) Oct 10 2012 http://d.puremagic.com/issues/show_bug.cgi?id=2584
- d-bugmail puremagic.com (8/11) Oct 10 2012 http://d.puremagic.com/issues/show_bug.cgi?id=2584
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http://d.puremagic.com/issues/show_bug.cgi?id=2584
Summary: GDC on ARM does not honor volatile
Product: DGCC aka GDC
Version: unspecified
Platform: Other
OS/Version: Other
Status: NEW
Severity: major
Priority: P2
Component: glue layer
AssignedTo: dvdfrdmn users.sf.net
ReportedBy: default_357-line yahoo.de
In GDC on ARM, the following code
struct Test {
uint* ptr;
uint write(uint i) { volatile (*ptr) = i; return i; }
}
void main() {
Test test; test.ptr = cast(uint*) 0xDEAD_BEEF;
test.write(0); test.write(0); test.write(0);
return;
}
generates this assembly: http://paste.dprogramming.com/dpep5uc3 .
Note how the 0 is only stored once, not thrice, in blatant violation of the
volatile.
--
Jan 13 2009
d-bugmail puremagic.com http://d.puremagic.com/issues/show_bug.cgi?id=2584 Sorry. Please disregard for now. I'm seeing conflicting results. --
Jan 13 2009
http://d.puremagic.com/issues/show_bug.cgi?id=2584
Right. Here we go. I had testcased it incorrectly.
The code to reproduce the error is
struct Test {
uint* ptr;
uint write(uint i) { volatile (*ptr) = i; return i; }
static Test opCall() { // it has to be returned by a function call, otherwise
the error doesn't happen
Test res;
res.ptr = cast(uint*) 0xDEAF_D00D;
return res;
}
}
void main() {
auto mat = Test();
asm { " baz"; }; // added to make sure it's the correct assembly this time
mat.write(0); mat.write(0); mat.write(0);
return;
}
And the assembly is here http://paste.dprogramming.com/dpag1p5d
--
Jan 13 2009
http://d.puremagic.com/issues/show_bug.cgi?id=2584
Alex Rønne Petersen <alex lycus.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
CC| |alex lycus.org
Resolution| |INVALID
CEST ---
Closing this since volatile is deprecated.
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Oct 09 2012
http://d.puremagic.com/issues/show_bug.cgi?id=2584
Manu <turkeyman gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |turkeyman gmail.com
Closing this since volatile is deprecated.
Really? It's still important... What's the work-around?
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Oct 10 2012
http://d.puremagic.com/issues/show_bug.cgi?id=2584It is indeed important. It's also now unreplicable. http://paste.dprogramming.com/dpsuffnm Gonna put this down to a bug in gcc-4.1 that has since been fixed. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------Closing this since volatile is deprecated.Really? It's still important... What's the work-around?
Oct 10 2012
http://d.puremagic.com/issues/show_bug.cgi?id=2584
Iain Buclaw <ibuclaw ubuntu.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|INVALID |FIXED
Note:
The D2-way of doing this is by using shared.
struct Test {
shared uint* ptr;
uint write(uint i) { (*ptr) = i; return i; }
}
void main() {
Test test; test.ptr = cast(uint*) 0xDEAD_BEEF;
test.write(0); test.write(0); test.write(0);
return;
}
Also guarantees that (*ptr) is stored thrice also.
----
_Dmain:
.fnstart
ldr r3, .L6
baz
str r0, [r3]
str r0, [r3]
str r0, [r3]
bx lr
.fnend
Regards,
Iain
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Oct 10 2012
http://d.puremagic.com/issues/show_bug.cgi?id=2584Note: The D2-way of doing this is by using shared.Really? I thought it was nothing more than a type-safety marker. So shared actually makes a variable volatile? -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Oct 10 2012
http://d.puremagic.com/issues/show_bug.cgi?id=2584Not the variable, but it's type is qualified as volatile, this produces subtly different codegen (IIRC volatile on the var would mean it is loaded thrice also). Given it's use in atomics, and that data-depending ordering is essential. I felt this to be important. Similarly for immutable, which sets the type as being const qualified. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------Note: The D2-way of doing this is by using shared.Really? I thought it was nothing more than a type-safety marker. So shared actually makes a variable volatile?
Oct 10 2012