digitalmars.D.bugs - [Issue 2356] New: array literal as non static initializer generates horribly inefficient code.
- d-bugmail puremagic.com (52/52) Sep 11 2008 http://d.puremagic.com/issues/show_bug.cgi?id=2356
- d-bugmail puremagic.com (10/10) Sep 15 2008 http://d.puremagic.com/issues/show_bug.cgi?id=2356
- d-bugmail puremagic.com (8/8) Apr 08 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2356
- d-bugmail puremagic.com (10/10) Jul 19 2010 http://d.puremagic.com/issues/show_bug.cgi?id=2356
- d-bugmail puremagic.com (10/10) Sep 09 2011 http://d.puremagic.com/issues/show_bug.cgi?id=2356
- d-bugmail puremagic.com (17/17) Sep 09 2011 http://d.puremagic.com/issues/show_bug.cgi?id=2356
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http://d.puremagic.com/issues/show_bug.cgi?id=2356
Summary: array literal as non static initializer generates
horribly inefficient code.
Product: D
Version: unspecified
Platform: PC
OS/Version: Linux
Status: NEW
Keywords: wrong-code
Severity: major
Priority: P2
Component: DMD
AssignedTo: bugzilla digitalmars.com
ReportedBy: tomas famolsen.dk
this simple test:
void main()
{
int[3] x = [1,2,3];
}
should just initialize x with the values 1,2,3
what happens in reality is not as nice as this output of obj2asm shows:
_Dmain:
push EBP
mov EBP,ESP
sub ESP,0Ch
push EBX
lea EAX,-0Ch[EBP]
push EAX
push 3
push 3
push 2
push 1
push 3
mov ECX,offset FLAT:_D11TypeInfo_Ai6__initZ SYM32
push ECX
call near ptr _d_arrayliteralT PC32
add ESP,014h
mov EDX,EAX
mov EBX,3
push EDX
push EBX
push 4
call near ptr _d_arraycopy PC32
xor EAX,EAX
add ESP,014h
pop EBX
leave
ret
I'm marking it wrong-code, even though the code does compile and link, it's
just wrong ... I'm using 1.034 but I'd guess it's an older bug, so I'm not
marking a specific version.
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Sep 11 2008
d-bugmail puremagic.com
http://d.puremagic.com/issues/show_bug.cgi?id=2356
tomas famolsen.dk changed:
What |Removed |Added
----------------------------------------------------------------------------
Version|unspecified |1.034
I think this issue might have been introduced in DMD 1.034, as I've hit several
issues in LLVMDC, that used to work, due to some initializers suddenly being
ArrayLiterals instead of ArrayInitializers. Marking version 1.034.
--
Sep 15 2008
http://d.puremagic.com/issues/show_bug.cgi?id=2356
clugdbug yahoo.com.au changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords|wrong-code |performance
This is a performance issue, not wrong-code.
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Apr 08 2009
http://d.puremagic.com/issues/show_bug.cgi?id=2356
bearophile_hugs eml.cc changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |bearophile_hugs eml.cc
*** Issue 4488 has been marked as a duplicate of this issue. ***
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Jul 19 2010
http://d.puremagic.com/issues/show_bug.cgi?id=2356
Kenji Hara <k.hara.pg gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |patch
https://github.com/D-Programming-Language/dmd/pull/375
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Sep 09 2011
http://d.puremagic.com/issues/show_bug.cgi?id=2356 After applying my patch, the sample code generates like follows: (output of ddbg in 64-bit Windows 7) c:\d\test.d:1 void main() 00402010: c80c0000 enter 0xc, 0x0 c:\d\test.d:3 int[3] x = [1,2,3]; 00402014: c745f401000000 mov dword [ebp-0xc], 0x1 0040201b: c745f802000000 mov dword [ebp-0x8], 0x2 00402022: c745fc03000000 mov dword [ebp-0x4], 0x3 00402029: 31c0 xor eax, eax test.obj 0040202b: c9 leave 0040202c: c3 ret -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Sep 09 2011
http://d.puremagic.com/issues/show_bug.cgi?id=2356
dawg dawgfoto.de changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |dawg dawgfoto.de
This is also a huge issue when assigning .init to a static array.
ubyte[1024] v;
v = typeof(v).init;
This will generate a dynamically allocated [0, 0, 0 ... ] Arrayliteral for the
rhs expression before calling _d_arraycopy. Even worse the allocated
ArrayLiteral is initialized using 1024 comma expressions. Using -O the compiler
will subsequently almost starve from O(N^2) behavior during comsub
eliminations.
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Oct 07 2011
http://d.puremagic.com/issues/show_bug.cgi?id=2356
yebblies <yebblies gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rsinfu gmail.com
*** Issue 4298 has been marked as a duplicate of this issue. ***
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Feb 01 2012
http://d.puremagic.com/issues/show_bug.cgi?id=2356
yebblies <yebblies gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |sean invisibleduck.org
*** Issue 4881 has been marked as a duplicate of this issue. ***
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Feb 01 2012
http://d.puremagic.com/issues/show_bug.cgi?id=2356
yebblies <yebblies gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jarrett.billingsley gmail.c
| |om
*** Issue 2237 has been marked as a duplicate of this issue. ***
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Feb 02 2012
http://d.puremagic.com/issues/show_bug.cgi?id=2356
Kenji Hara <k.hara.pg gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords|patch |
---
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May 05 2012
http://d.puremagic.com/issues/show_bug.cgi?id=2356
Jonathan M Davis <jmdavisProg gmx.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |malteskarupke web.de
PDT ---
*** Issue 8820 has been marked as a duplicate of this issue. ***
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Oct 14 2012
http://d.puremagic.com/issues/show_bug.cgi?id=2356
yebblies <yebblies gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |siegelords_abode yahoo.com
*** Issue 8903 has been marked as a duplicate of this issue. ***
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Oct 28 2012
http://d.puremagic.com/issues/show_bug.cgi?id=2356
Denis Shelomovskij <verylonglogin.reg gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |verylonglogin.reg gmail.com
2012-10-30 17:17:29 MSK ---
Workaround for those who like "a, b, c" initialization but need more
performance (not: it still calls `_d_arraycopy`):
---
T[n] makeStaticArray(T, size_t n)(T[n] data...)
// { return data; }
{ T[n] res; res = data; return res; } // Issue 8914 workaround
void setStaticArray(T, size_t n)(ref T[n] array, T[n] data...)
{ array = data; }
void main()
{
auto x = makeStaticArray(1, 2, 3);
static assert(is(typeof(x) == int[3]));
assert(x == [1, 2, 3]);
int[3] y;
y.setStaticArray(1, 2, 3);
assert(y == [1, 2, 3]);
}
---
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Oct 30 2012
http://d.puremagic.com/issues/show_bug.cgi?id=2356
Kenji Hara <k.hara.pg gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |pull
---
New D2 fix:
https://github.com/D-Programming-Language/dmd/pull/1883
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Apr 10 2013
http://d.puremagic.com/issues/show_bug.cgi?id=2356New D2 fix: https://github.com/D-Programming-Language/dmd/pull/1883From the pull request (dmd -O -inline -g test after): c:\d\test.d:18 int[3] y = [n, n, n]; 004020aa: 6a03 push 0x3 004020ac: 6a05 push 0x5 004020ae: 8d4c241c lea ecx, [esp+0x1c] 004020b2: 51 push ecx 004020b3: e880020000 call 0x402338 __memset32 Isn't calling memset for just 3 integers slower than inlining their assignments? I suggest to not call memset if the number of bytes to be copied is so small (I think LDC is already doing similar optimizations). Maybe a benchmark is also useful here. c:\d\test.d:20 S[3] z = [s2, s2, s2]; 004020b8: 8d542418 lea edx, [esp+0x18] 004020bc: 52 push edx 004020bd: 8d442430 lea eax, [esp+0x30] 004020c1: e86affffff call 0x402030 test.S.__cpctor c:\d\test.d:3 004020c6: 8d5c2418 lea ebx, [esp+0x18] 004020ca: 53 push ebx 004020cb: 8d442434 lea eax, [esp+0x34] 004020cf: e85cffffff call 0x402030 test.S.__cpctor c:\d\test.d:3 004020d4: 53 push ebx 004020d5: 8d442438 lea eax, [esp+0x38] 004020d9: e852ffffff call 0x402030 test.S.__cpctor c:\d\test.d:3 004020de: 83c40c add esp, 0xc 004020e1: 31c0 xor eax, eax If the s2 variable already contains the struct, then what's the purpose of those calls to 0x402030? In the "before" there are no calls to struct constructors: c:\d\test.d:20 S[3] z = [s2, s2, s2]; 00403913: 8d542474 lea edx, [esp+0x74] 00403917: b960014200 mov ecx, 0x420160 0040391c: 52 push edx 0040391d: 6a03 push 0x3 0040391f: 6a03 push 0x3 00403921: 51 push ecx 00403922: e8fd0a0000 call 0x404424 __d_arrayliteralTX 00403927: 83c408 add esp, 0x8 0040392a: 8d542470 lea edx, [esp+0x70] 0040392e: 52 push edx 0040392f: 89c6 mov esi, eax -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Apr 10 2013
http://d.puremagic.com/issues/show_bug.cgi?id=2356 ---It is lowered to: int[3] y = void; y[] = n; And currently dmd uses memset for `y[] = n;`. It is another optimization issue.New D2 fix: https://github.com/D-Programming-Language/dmd/pull/1883From the pull request (dmd -O -inline -g test after): c:\d\test.d:18 int[3] y = [n, n, n]; 004020aa: 6a03 push 0x3 004020ac: 6a05 push 0x5 004020ae: 8d4c241c lea ecx, [esp+0x1c] 004020b2: 51 push ecx 004020b3: e880020000 call 0x402338 __memset32 Isn't calling memset for just 3 integers slower than inlining their assignments? I suggest to not call memset if the number of bytes to be copied is so small (I think LDC is already doing similar optimizations). Maybe a benchmark is also useful here.c:\d\test.d:20 S[3] z = [s2, s2, s2]; 004020b8: 8d542418 lea edx, [esp+0x18] 004020bc: 52 push edx 004020bd: 8d442430 lea eax, [esp+0x30] 004020c1: e86affffff call 0x402030 test.S.__cpctor c:\d\test.d:3 004020c6: 8d5c2418 lea ebx, [esp+0x18] 004020ca: 53 push ebx 004020cb: 8d442434 lea eax, [esp+0x34] 004020cf: e85cffffff call 0x402030 test.S.__cpctor c:\d\test.d:3 004020d4: 53 push ebx 004020d5: 8d442438 lea eax, [esp+0x38] 004020d9: e852ffffff call 0x402030 test.S.__cpctor c:\d\test.d:3 004020de: 83c40c add esp, 0xc 004020e1: 31c0 xor eax, eax If the s2 variable already contains the struct, then what's the purpose of those calls to 0x402030? In the "before" there are no calls to struct constructors: c:\d\test.d:20 S[3] z = [s2, s2, s2]; 00403913: 8d542474 lea edx, [esp+0x74] 00403917: b960014200 mov ecx, 0x420160 0040391c: 52 push edx 0040391d: 6a03 push 0x3 0040391f: 6a03 push 0x3 00403921: 51 push ecx 00403922: e8fd0a0000 call 0x404424 __d_arrayliteralTX 00403927: 83c408 add esp, 0x8 0040392a: 8d542470 lea edx, [esp+0x70] 0040392e: 52 push edx 0040392f: 89c6 mov esi, eaxBefore, cpctor(==postblit) calls are done in __d_arrayliteralTX, so they are hidden. Now they are directly called on the stack memory z[0..3]. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Apr 10 2013
http://d.puremagic.com/issues/show_bug.cgi?id=2356It is lowered to: int[3] y = void; y[] = n; And currently dmd uses memset for `y[] = n;`. It is another optimization issue.OK.Before, cpctor(==postblit) calls are done in __d_arrayliteralTX, so they are hidden. Now they are directly called on the stack memory z[0..3].Sorry I have missed it was the postblit, thank you. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Apr 10 2013
http://d.puremagic.com/issues/show_bug.cgi?id=2356 Commits pushed to master at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/8cd5f790a78e7514e46618d0325e92cbd6e00e48 fix Issue 2356 - array literal as non static initializer generates horribly inefficient code. https://github.com/D-Programming-Language/dmd/commit/d4b20baee7a1c9ee8a9271724feb5d1031e773d4 Issue 2356 - array literal as non static initializer generates horribly inefficient code. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Apr 11 2013
http://d.puremagic.com/issues/show_bug.cgi?id=2356 The patch seems to work. With it I have removed five optimizations from my code. Very good. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Apr 11 2013
http://d.puremagic.com/issues/show_bug.cgi?id=2356
Andrei Alexandrescu <andrei erdani.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
CC| |andrei erdani.com
Resolution| |FIXED
06:12:47 PDT ---
Thanks, Kenji!
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Apr 11 2013
http://d.puremagic.com/issues/show_bug.cgi?id=2356
Benjamin Thaut <code benjamin-thaut.de> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |code benjamin-thaut.de
00:04:57 PDT ---
Awesome, thanks for fixing this. This was my number 1 most annoying bug in D.
Because when not using a GC the old behavior always leaked memory.
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Jun 06 2013
http://d.puremagic.com/issues/show_bug.cgi?id=2356
2013-10-25 00:21:28 MSD ---
The fix is partially reverted in dmd pull 2682 [1] as it introduced Issue
11238.
Only construction is optimized now:
---
void main()
{
int[2] m = [4, 6]; // still optimized
m = [m[1], m[0]]; // swap, currently calls `_d_arrayliteralTX`
assert(m == [6, 4]); // was [6, 6] with original fix (Issue 11238)
}
---
Opened Issue 11345 for assignment case.
Also some duplicates of current issue and duplicates of duplicates of current
issue are now really duplicates of Issue 11345.
[1] https://github.com/D-Programming-Language/dmd/pull/2682
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Oct 24 2013
http://d.puremagic.com/issues/show_bug.cgi?id=2356 2013-10-25 00:45:30 MSD ---Also some duplicates of current issue and duplicates of duplicates of current issue are now really duplicates of Issue 11345.Looks like Issue 4881 was the only one. Changed its "DUPLICATE of". -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Oct 24 2013