Monomorphize various things (#1914)

bjorn3 · bjorn3 · commit 2fcd8a3fb06e · 2021-04-28T19:04:00.000Z
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 ```
diff --git a/crates/bevy_ecs/src/schedule/mod.rs b/crates/bevy_ecs/src/schedule/mod.rs
@@ -20,6 +20,8 @@ pub use system_container::*;
 pub use system_descriptor::*;
 pub use system_set::*;
 
+use std::fmt::Debug;
+
 use crate::{
     system::{IntoSystem, System},
     world::World,
@@ -144,14 +146,19 @@ impl Schedule {
         stage_label: impl StageLabel,
         system: impl Into<SystemDescriptor>,
     ) -> &mut Self {
+        // Use a function instead of a closure to ensure that it is codegend inside bevy_ecs instead
+        // of the game. Closures inherit generic parameters from their enclosing function.
+        #[cold]
+        fn stage_not_found(stage_label: &dyn Debug) -> ! {
+            panic!(
+                "Stage '{:?}' does not exist or is not a SystemStage",
+                stage_label
+            )
+        }
+
         let stage = self
             .get_stage_mut::<SystemStage>(&stage_label)
-            .unwrap_or_else(move || {
-                panic!(
-                    "Stage '{:?}' does not exist or is not a SystemStage",
-                    stage_label
-                )
-            });
+            .unwrap_or_else(move || stage_not_found(&stage_label));
         stage.add_system(system);
         self
     }
