digitalmars.D.bugs - [Issue 4298] New: Constant array translated to unnecessary array literal creation
- d-bugmail puremagic.com (47/47) Jun 08 2010 http://d.puremagic.com/issues/show_bug.cgi?id=4298
- d-bugmail puremagic.com (29/29) Jun 08 2010 http://d.puremagic.com/issues/show_bug.cgi?id=4298
- d-bugmail puremagic.com (26/26) Jun 15 2010 http://d.puremagic.com/issues/show_bug.cgi?id=4298
- d-bugmail puremagic.com (14/19) Jun 15 2010 http://d.puremagic.com/issues/show_bug.cgi?id=4298
- d-bugmail puremagic.com (10/10) Jul 25 2010 http://d.puremagic.com/issues/show_bug.cgi?id=4298
- d-bugmail puremagic.com (10/10) Sep 08 2010 http://d.puremagic.com/issues/show_bug.cgi?id=4298
- d-bugmail puremagic.com (12/12) Feb 01 2012 http://d.puremagic.com/issues/show_bug.cgi?id=4298
http://d.puremagic.com/issues/show_bug.cgi?id=4298
Summary: Constant array translated to unnecessary array literal
creation
Product: D
Version: 2.041
Platform: x86
OS/Version: All
Status: NEW
Keywords: performance
Severity: normal
Priority: P2
Component: DMD
AssignedTo: nobody puremagic.com
ReportedBy: rsinfu gmail.com
---
Using constant (const or immutable) dynamic array causes unnecessary
array literal creation if the constant array has an initializer.
This behavior degrades performance, and also causes the bug 4297.
Test code and the disassembled output:
--------------------
immutable int[] TABLE = [ 1, 2, 3 ];
void foo()
{
const(int)[] tab = TABLE;
}
--------------------
_D4test3fooFZv:
push EBP
mov EBP,ESP
push EBX
push 3
push 2
push 1
push 3
mov EAX,offset FLAT:_D12TypeInfo_Axi6__initZ SYM32
push EAX
call _d_arrayliteralT PC32
mov ECX,EAX
mov EBX,3
add ESP,014h
pop EBX
pop EBP
ret
--------------------
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Jun 08 2010
d-bugmail puremagic.com
http://d.puremagic.com/issues/show_bug.cgi?id=4298
Shin Fujishiro <rsinfu gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |patch
---
Patch against DMD r526:
====================
--- src/optimize.c
+++ src/optimize.c
-58,10 +58,9 Expression *expandVar(int result, VarDeclaration *v)
return e;
}
- Type *tb = v->type->toBasetype();
if (result & WANTinterpret ||
v->storage_class & STCmanifest ||
- (tb->ty != Tsarray && tb->ty != Tstruct)
+ v->type->isscalar()
)
{
if (v->init)
====================
The if condition is changed so that only scalar constants are expanded.
Affected types are Tarray, Taarray, Tclass and Tdelegate. Arrays and
associative arrays should not be expanded (the reported problem); classes and
delegates are not necessary to be expanded.
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Jun 08 2010
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Shin Fujishiro <rsinfu gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords|patch |
---
--------------------
void main()
{
immutable s = "abc";
auto t = s[0 .. $ - 1];
}
--------------------
% dmd -run test
test.o(.text._Dmain+0x1a): In function `_Dmain':
: undefined reference to `_D4test4mainFZv8__dollarxk'
--------------------
The link error does not occur if the dollar $ is replaced with s.length.
The real cause of the link error may be elsewhere (only $ causes a link
error?), but the patch itself doesn't work anyway. So I remove the 'patch'
keyword.
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Jun 15 2010
http://d.puremagic.com/issues/show_bug.cgi?id=4298
Shin Fujishiro <rsinfu gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |patch
Depends on| |3779
---
The link error does not occur if the dollar $ is replaced with s.length.
The real cause of the link error may be elsewhere (only $ causes a link
error?), but the patch itself doesn't work anyway. So I remove the 'patch'
keyword.
The linker error about __dollar is caused by bug 3779. I think the patch in
a dependency to bug 3779.
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Jun 15 2010
http://d.puremagic.com/issues/show_bug.cgi?id=4298
David Simcha <dsimcha yahoo.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |dsimcha yahoo.com
*** Issue 3370 has been marked as a duplicate of this issue. ***
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Jul 25 2010
http://d.puremagic.com/issues/show_bug.cgi?id=4298
David Simcha <dsimcha yahoo.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |r.sagitario gmx.de
*** Issue 4631 has been marked as a duplicate of this issue. ***
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Sep 08 2010
http://d.puremagic.com/issues/show_bug.cgi?id=4298
yebblies <yebblies gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
CC| |yebblies gmail.com
Resolution| |DUPLICATE
*** This issue has been marked as a duplicate of issue 2356 ***
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Feb 01 2012