[Merged by Bors] - Monomorphize various things #1914

bjorn3 · 2021-04-13T17:56:32Z

Based on #1910

This shrinks breakout from 310k to 293k. Most of the win is in outlining the drop glue of App. The other two commits save about 800 bytes total when using two empty systems and two simple resources.

After this PR the full disassembly for

fn main() {
    App::build().run();
}

is about as minimal as it gets, so pretty much all other costs scale linear in the amount of resources, systems, etc.

0000000000001100 <_ZN4core3ptr54drop_in_place$LT$bevy_app..app_builder..AppBuilder$GT$17h76850422c20653deE>:
    1100:       ff 25 52 21 00 00       jmpq   *0x2152(%rip)        # 3258 <_ZN60_$LT$bevy_app..app..App$u20$as$u20$core..ops..drop..Drop$GT$4drop17h67d177ae549d917bE@Base>
    1106:       cc                      int3   
    1107:       cc                      int3   
    1108:       cc                      int3   
    1109:       cc                      int3   
    110a:       cc                      int3   
    110b:       cc                      int3   
    110c:       cc                      int3   
    110d:       cc                      int3   
    110e:       cc                      int3   
    110f:       cc                      int3   

0000000000001110 <_ZN8breakout4main17h7cbe07b319de1042E>:
    1110:       53                      push   %rbx
    1111:       48 81 ec 00 03 00 00    sub    $0x300,%rsp
    1118:       48 8d 5c 24 08          lea    0x8(%rsp),%rbx
    111d:       48 89 df                mov    %rbx,%rdi
    1120:       ff 15 3a 21 00 00       callq  *0x213a(%rip)        # 3260 <_ZN8bevy_app3app3App5build17h8b0ea6be9050d6ccE@Base>
    1126:       48 89 df                mov    %rbx,%rdi
    1129:       ff 15 39 21 00 00       callq  *0x2139(%rip)        # 3268 <_ZN8bevy_app11app_builder10AppBuilder3run17hfc8cf50692acdbdeE@Base>
    112f:       48 8d 7c 24 08          lea    0x8(%rsp),%rdi
    1134:       ff 15 1e 21 00 00       callq  *0x211e(%rip)        # 3258 <_ZN60_$LT$bevy_app..app..App$u20$as$u20$core..ops..drop..Drop$GT$4drop17h67d177ae549d917bE@Base>
    113a:       48 81 c4 00 03 00 00    add    $0x300,%rsp
    1141:       5b                      pop    %rbx
    1142:       c3                      retq   
    1143:       48 89 c3                mov    %rax,%rbx
    1146:       48 8d 7c 24 08          lea    0x8(%rsp),%rdi
    114b:       e8 b0 ff ff ff          callq  1100 <_ZN4core3ptr54drop_in_place$LT$bevy_app..app_builder..AppBuilder$GT$17h76850422c20653deE>
    1150:       48 89 df                mov    %rbx,%rdi
    1153:       e8 18 01 00 00          callq  1270 <_Unwind_Resume@plt>
    1158:       0f 0b                   ud2    
    115a:       cc                      int3   
    115b:       cc                      int3   
    115c:       cc                      int3   
    115d:       cc                      int3   
    115e:       cc                      int3   
    115f:       cc                      int3   

0000000000001160 <main>:
    1160:       48 83 ec 08             sub    $0x8,%rsp
    1164:       48 89 f1                mov    %rsi,%rcx
    1167:       48 63 d7                movslq %edi,%rdx
    116a:       48 8d 05 9f ff ff ff    lea    -0x61(%rip),%rax        # 1110 <_ZN8breakout4main17h7cbe07b319de1042E>
    1171:       48 89 04 24             mov    %rax,(%rsp)
    1175:       48 8d 35 94 1e 00 00    lea    0x1e94(%rip),%rsi        # 3010 <__init_array_end>
    117c:       48 89 e7                mov    %rsp,%rdi
    117f:       ff 15 eb 20 00 00       callq  *0x20eb(%rip)        # 3270 <_ZN3std2rt19lang_start_internal17he77194431b0ee4a2E@Base>
    1185:       59                      pop    %rcx
    1186:       c3                      retq   
    1187:       cc                      int3   
    1188:       cc                      int3   
    1189:       cc                      int3   
    118a:       cc                      int3   
    118b:       cc                      int3   
    118c:       cc                      int3   
    118d:       cc                      int3   
    118e:       cc                      int3   
    118f:       cc                      int3   

0000000000001190 <_ZN3std2rt10lang_start28_$u7b$$u7b$closure$u7d$$u7d$17h83a5b8d55f23dff8E.llvm.909376793398482062>:
    1190:       48 83 ec 08             sub    $0x8,%rsp
    1194:       48 8b 3f                mov    (%rdi),%rdi
    1197:       e8 54 ff ff ff          callq  10f0 <_ZN3std10sys_common9backtrace28__rust_begin_short_backtrace17h6e238af75680eb28E>
    119c:       31 c0                   xor    %eax,%eax
    119e:       59                      pop    %rcx
    119f:       c3                      retq   

00000000000011a0 <_ZN4core3ops8function6FnOnce40call_once$u7b$$u7b$vtable.shim$u7d$$u7d$17hb05d591cd29dea4fE.llvm.909376793398482062>:
    11a0:       48 83 ec 08             sub    $0x8,%rsp
    11a4:       48 8b 3f                mov    (%rdi),%rdi
    11a7:       e8 44 ff ff ff          callq  10f0 <_ZN3std10sys_common9backtrace28__rust_begin_short_backtrace17h6e238af75680eb28E>
    11ac:       31 c0                   xor    %eax,%eax
    11ae:       59                      pop    %rcx
    11af:       c3                      retq   

00000000000011b0 <_ZN4core3ptr85drop_in_place$LT$std..rt..lang_start$LT$$LP$$RP$$GT$..$u7b$$u7b$closure$u7d$$u7d$$GT$17he9aeeba375093b99E.llvm.909376793398482062>:
    11b0:       c3                      retq   
    11b1:       cc                      int3   
    11b2:       cc                      int3   
    11b3:       cc                      int3   
    11b4:       cc                      int3   
    11b5:       cc                      int3   
    11b6:       cc                      int3   
    11b7:       cc                      int3   
    11b8:       cc                      int3   
    11b9:       cc                      int3   
    11ba:       cc                      int3   
    11bb:       cc                      int3   
    11bc:       cc                      int3   
    11bd:       cc                      int3   
    11be:       cc                      int3   
    11bf:       cc                      int3

NathanSWard · 2021-04-13T18:01:37Z

crates/bevy_app/src/app.rs

+}
+
+// Outlined to ensure that a lot of drop glue is codegened inside bevy_app instead of the game.
+unsafe fn drop_app(app: &mut App) {


Add a // SAFE comment explaining why this is safe to use.
It's pretty obvious why it is safe, but I'd argue that every use of unsafe needs to have a // SAFETY comment to go along with it.

More specifically the format is:

/// # Safety /// <explination> unsafe fn drop_app(app: &mut App) {}

crates/bevy_app/src/plugin_group.rs

NathanSWard · 2021-04-13T18:29:30Z

crates/bevy_app/src/app.rs

-    pub world: World,
-    pub runner: Box<dyn Fn(App)>,
-    pub schedule: Schedule,
+    pub world: ManuallyDrop<World>,


I'm a little conflicted here.
While utilizing ManuallyDrop<T> helps reduce the binary size, I don't know if it's worth the extra complexity.
I'm not completely against using it, I just feel it's a little counter-intuitive and unnecessary for the only benefit being a smaller executable.
(Again, we need to consider a space vs performance trade off)

Haha my comment is related but you submitted while I was still typing it :)

cart · 2021-04-13T18:40:28Z

crates/bevy_app/src/app.rs

-    pub world: World,
-    pub runner: Box<dyn Fn(App)>,
-    pub schedule: Schedule,
+    pub world: ManuallyDrop<World>,


This is a drop in code clarity / friendliness for a relatively "core" type that I expect people to look at on a regular basis (and also an increase in unsafe).

Can we discuss a bit what this ~17k wins us? If this were optimizing for web/wasm deployments (which have tight network constraints / lots of people that care about load times), that would make more sense to me. But this is specifically optimizing dynamically linked outputs, which generally won't be published.

This change also only affects "top level" apps, so this won't come into play for "dynamically linked plugins" if we decide to go that route in the future.

So I think the intent here is to optimize "iterative compile times" when using --features dynamic. If so, it would be good to measure how much we're winning here and weight that against the negatives pointed out above.

So I think the intent here is to optimize "iterative compile times" when using --features dynamic.

Mostly correct, though it should also save some time without --features dynamic too. Before this PR the drop glue would be generated both in the game (for unwinding on panics) and in bevy_app (for dropping at the end of AppBuilder::run). After this PR it is only generated in bevy_app.

… path

bjorn3 · 2021-04-28T17:58:10Z

I have dropped the drop glue commit and will instead wait for rust-lang/rust#84175. 39d71e2 (Use a function instead of a closure for the add_system_to_stage error path) is still part of this PR.

cart · 2021-04-28T18:44:05Z

bors r+

Based on #1910 This shrinks breakout from 310k to 293k. Most of the win is in outlining the drop glue of `App`. The other two commits save about 800 bytes total when using two empty systems and two simple resources. After this PR the full disassembly for ```rust fn main() { App::build().run(); } ``` is about as minimal as it gets, so pretty much all other costs scale linear in the amount of resources, systems, etc. ```asm 0000000000001100 <_ZN4core3ptr54drop_in_place$LT$bevy_app..app_builder..AppBuilder$GT$17h76850422c20653deE>: 1100: ff 25 52 21 00 00 jmpq *0x2152(%rip) # 3258 <_ZN60_$LT$bevy_app..app..App$u20$as$u20$core..ops..drop..Drop$GT$4drop17h67d177ae549d917bE@Base> 1106: cc int3 1107: cc int3 1108: cc int3 1109: cc int3 110a: cc int3 110b: cc int3 110c: cc int3 110d: cc int3 110e: cc int3 110f: cc int3 0000000000001110 <_ZN8breakout4main17h7cbe07b319de1042E>: 1110: 53 push %rbx 1111: 48 81 ec 00 03 00 00 sub $0x300,%rsp 1118: 48 8d 5c 24 08 lea 0x8(%rsp),%rbx 111d: 48 89 df mov %rbx,%rdi 1120: ff 15 3a 21 00 00 callq *0x213a(%rip) # 3260 <_ZN8bevy_app3app3App5build17h8b0ea6be9050d6ccE@Base> 1126: 48 89 df mov %rbx,%rdi 1129: ff 15 39 21 00 00 callq *0x2139(%rip) # 3268 <_ZN8bevy_app11app_builder10AppBuilder3run17hfc8cf50692acdbdeE@Base> 112f: 48 8d 7c 24 08 lea 0x8(%rsp),%rdi 1134: ff 15 1e 21 00 00 callq *0x211e(%rip) # 3258 <_ZN60_$LT$bevy_app..app..App$u20$as$u20$core..ops..drop..Drop$GT$4drop17h67d177ae549d917bE@Base> 113a: 48 81 c4 00 03 00 00 add $0x300,%rsp 1141: 5b pop %rbx 1142: c3 retq 1143: 48 89 c3 mov %rax,%rbx 1146: 48 8d 7c 24 08 lea 0x8(%rsp),%rdi 114b: e8 b0 ff ff ff callq 1100 <_ZN4core3ptr54drop_in_place$LT$bevy_app..app_builder..AppBuilder$GT$17h76850422c20653deE> 1150: 48 89 df mov %rbx,%rdi 1153: e8 18 01 00 00 callq 1270 <_Unwind_Resume@plt> 1158: 0f 0b ud2 115a: cc int3 115b: cc int3 115c: cc int3 115d: cc int3 115e: cc int3 115f: cc int3 0000000000001160 <main>: 1160: 48 83 ec 08 sub $0x8,%rsp 1164: 48 89 f1 mov %rsi,%rcx 1167: 48 63 d7 movslq %edi,%rdx 116a: 48 8d 05 9f ff ff ff lea -0x61(%rip),%rax # 1110 <_ZN8breakout4main17h7cbe07b319de1042E> 1171: 48 89 04 24 mov %rax,(%rsp) 1175: 48 8d 35 94 1e 00 00 lea 0x1e94(%rip),%rsi # 3010 <__init_array_end> 117c: 48 89 e7 mov %rsp,%rdi 117f: ff 15 eb 20 00 00 callq *0x20eb(%rip) # 3270 <_ZN3std2rt19lang_start_internal17he77194431b0ee4a2E@Base> 1185: 59 pop %rcx 1186: c3 retq 1187: cc int3 1188: cc int3 1189: cc int3 118a: cc int3 118b: cc int3 118c: cc int3 118d: cc int3 118e: cc int3 118f: cc int3 0000000000001190 <_ZN3std2rt10lang_start28_$u7b$$u7b$closure$u7d$$u7d$17h83a5b8d55f23dff8E.llvm.909376793398482062>: 1190: 48 83 ec 08 sub $0x8,%rsp 1194: 48 8b 3f mov (%rdi),%rdi 1197: e8 54 ff ff ff callq 10f0 <_ZN3std10sys_common9backtrace28__rust_begin_short_backtrace17h6e238af75680eb28E> 119c: 31 c0 xor %eax,%eax 119e: 59 pop %rcx 119f: c3 retq 00000000000011a0 <_ZN4core3ops8function6FnOnce40call_once$u7b$$u7b$vtable.shim$u7d$$u7d$17hb05d591cd29dea4fE.llvm.909376793398482062>: 11a0: 48 83 ec 08 sub $0x8,%rsp 11a4: 48 8b 3f mov (%rdi),%rdi 11a7: e8 44 ff ff ff callq 10f0 <_ZN3std10sys_common9backtrace28__rust_begin_short_backtrace17h6e238af75680eb28E> 11ac: 31 c0 xor %eax,%eax 11ae: 59 pop %rcx 11af: c3 retq 00000000000011b0 <_ZN4core3ptr85drop_in_place$LT$std..rt..lang_start$LT$$LP$$RP$$GT$..$u7b$$u7b$closure$u7d$$u7d$$GT$17he9aeeba375093b99E.llvm.909376793398482062>: 11b0: c3 retq 11b1: cc int3 11b2: cc int3 11b3: cc int3 11b4: cc int3 11b5: cc int3 11b6: cc int3 11b7: cc int3 11b8: cc int3 11b9: cc int3 11ba: cc int3 11bb: cc int3 11bc: cc int3 11bd: cc int3 11be: cc int3 11bf: cc int3 ```

bors · 2021-04-28T19:23:57Z

Pull request successfully merged into main.

Build succeeded:

Based on bevyengine#1910 This shrinks breakout from 310k to 293k. Most of the win is in outlining the drop glue of `App`. The other two commits save about 800 bytes total when using two empty systems and two simple resources. After this PR the full disassembly for ```rust fn main() { App::build().run(); } ``` is about as minimal as it gets, so pretty much all other costs scale linear in the amount of resources, systems, etc. ```asm 0000000000001100 <_ZN4core3ptr54drop_in_place$LT$bevy_app..app_builder..AppBuilder$GT$17h76850422c20653deE>: 1100: ff 25 52 21 00 00 jmpq *0x2152(%rip) # 3258 <_ZN60_$LT$bevy_app..app..App$u20$as$u20$core..ops..drop..Drop$GT$4drop17h67d177ae549d917bE@Base> 1106: cc int3 1107: cc int3 1108: cc int3 1109: cc int3 110a: cc int3 110b: cc int3 110c: cc int3 110d: cc int3 110e: cc int3 110f: cc int3 0000000000001110 <_ZN8breakout4main17h7cbe07b319de1042E>: 1110: 53 push %rbx 1111: 48 81 ec 00 03 00 00 sub $0x300,%rsp 1118: 48 8d 5c 24 08 lea 0x8(%rsp),%rbx 111d: 48 89 df mov %rbx,%rdi 1120: ff 15 3a 21 00 00 callq *0x213a(%rip) # 3260 <_ZN8bevy_app3app3App5build17h8b0ea6be9050d6ccE@Base> 1126: 48 89 df mov %rbx,%rdi 1129: ff 15 39 21 00 00 callq *0x2139(%rip) # 3268 <_ZN8bevy_app11app_builder10AppBuilder3run17hfc8cf50692acdbdeE@Base> 112f: 48 8d 7c 24 08 lea 0x8(%rsp),%rdi 1134: ff 15 1e 21 00 00 callq *0x211e(%rip) # 3258 <_ZN60_$LT$bevy_app..app..App$u20$as$u20$core..ops..drop..Drop$GT$4drop17h67d177ae549d917bE@Base> 113a: 48 81 c4 00 03 00 00 add $0x300,%rsp 1141: 5b pop %rbx 1142: c3 retq 1143: 48 89 c3 mov %rax,%rbx 1146: 48 8d 7c 24 08 lea 0x8(%rsp),%rdi 114b: e8 b0 ff ff ff callq 1100 <_ZN4core3ptr54drop_in_place$LT$bevy_app..app_builder..AppBuilder$GT$17h76850422c20653deE> 1150: 48 89 df mov %rbx,%rdi 1153: e8 18 01 00 00 callq 1270 <_Unwind_Resume@plt> 1158: 0f 0b ud2 115a: cc int3 115b: cc int3 115c: cc int3 115d: cc int3 115e: cc int3 115f: cc int3 0000000000001160 <main>: 1160: 48 83 ec 08 sub $0x8,%rsp 1164: 48 89 f1 mov %rsi,%rcx 1167: 48 63 d7 movslq %edi,%rdx 116a: 48 8d 05 9f ff ff ff lea -0x61(%rip),%rax # 1110 <_ZN8breakout4main17h7cbe07b319de1042E> 1171: 48 89 04 24 mov %rax,(%rsp) 1175: 48 8d 35 94 1e 00 00 lea 0x1e94(%rip),%rsi # 3010 <__init_array_end> 117c: 48 89 e7 mov %rsp,%rdi 117f: ff 15 eb 20 00 00 callq *0x20eb(%rip) # 3270 <_ZN3std2rt19lang_start_internal17he77194431b0ee4a2E@Base> 1185: 59 pop %rcx 1186: c3 retq 1187: cc int3 1188: cc int3 1189: cc int3 118a: cc int3 118b: cc int3 118c: cc int3 118d: cc int3 118e: cc int3 118f: cc int3 0000000000001190 <_ZN3std2rt10lang_start28_$u7b$$u7b$closure$u7d$$u7d$17h83a5b8d55f23dff8E.llvm.909376793398482062>: 1190: 48 83 ec 08 sub $0x8,%rsp 1194: 48 8b 3f mov (%rdi),%rdi 1197: e8 54 ff ff ff callq 10f0 <_ZN3std10sys_common9backtrace28__rust_begin_short_backtrace17h6e238af75680eb28E> 119c: 31 c0 xor %eax,%eax 119e: 59 pop %rcx 119f: c3 retq 00000000000011a0 <_ZN4core3ops8function6FnOnce40call_once$u7b$$u7b$vtable.shim$u7d$$u7d$17hb05d591cd29dea4fE.llvm.909376793398482062>: 11a0: 48 83 ec 08 sub $0x8,%rsp 11a4: 48 8b 3f mov (%rdi),%rdi 11a7: e8 44 ff ff ff callq 10f0 <_ZN3std10sys_common9backtrace28__rust_begin_short_backtrace17h6e238af75680eb28E> 11ac: 31 c0 xor %eax,%eax 11ae: 59 pop %rcx 11af: c3 retq 00000000000011b0 <_ZN4core3ptr85drop_in_place$LT$std..rt..lang_start$LT$$LP$$RP$$GT$..$u7b$$u7b$closure$u7d$$u7d$$GT$17he9aeeba375093b99E.llvm.909376793398482062>: 11b0: c3 retq 11b1: cc int3 11b2: cc int3 11b3: cc int3 11b4: cc int3 11b5: cc int3 11b6: cc int3 11b7: cc int3 11b8: cc int3 11b9: cc int3 11ba: cc int3 11bb: cc int3 11bc: cc int3 11bd: cc int3 11be: cc int3 11bf: cc int3 ```

bjorn3 mentioned this pull request Apr 13, 2021

Tracking issue for dynamically linked executable size #1911

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NathanSWard reviewed Apr 13, 2021

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alice-i-cecile added C-Code-Quality A section of code that is hard to understand or change C-Performance A change motivated by improving speed, memory usage or compile times labels Apr 13, 2021

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bjorn3 force-pushed the monomorphize_various_things branch from be6ed55 to 41d9335 Compare April 13, 2021 19:32

bjorn3 mentioned this pull request Apr 13, 2021

Share drop glue too when -Zshare-generics is enabled rust-lang/rust#84175

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bjorn3 force-pushed the monomorphize_various_things branch from 41d9335 to e5ba919 Compare April 28, 2021 17:56

Use a function instead of a closure for the add_system_to_stage error…

39d71e2

… path

bjorn3 force-pushed the monomorphize_various_things branch from e5ba919 to 39d71e2 Compare April 28, 2021 17:57

bors bot changed the title ~~Monomorphize various things~~ [Merged by Bors] - Monomorphize various things Apr 28, 2021

bors bot closed this Apr 28, 2021

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[Merged by Bors] - Monomorphize various things #1914

[Merged by Bors] - Monomorphize various things #1914

bjorn3 commented Apr 13, 2021

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[Merged by Bors] - Monomorphize various things #1914

[Merged by Bors] - Monomorphize various things #1914

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