ghost
commented
1 year ago Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch, @kunalspathak See info in area-owners.md if you want to be subscribed.
Issue Details
```csharp void Foo(object o) { for (int i = 0; i < 100; i++) { if (o is string) Console.WriteLine("str!"); if (o is string) Console.WriteLine("str!"); } } ``` Current codegen: ```asm ; Method Prog:Foo(System.Object):this G_M20911_IG01: ;; offset=0000H 57 push rdi 56 push rsi 4883EC28 sub rsp, 40 488BF2 mov rsi, rdx 33FF xor edi, edi ;; ========= loop start ========= G_M20911_IG03: 488BCE mov rcx, rsi 4885C9 test rcx, rcx 741F je SHORT G_M20911_IG06 48B830A9B604F97F0000 mov rax, 0x7FF904B6A930 ; System.String 483901 cmp qword ptr [rcx], rax 7510 jne SHORT G_M20911_IG06 48B9C09530808C020000 mov rcx, 0x28C803095C0 ; 'str!' FF1576C79000 call [System.Console:WriteLine(System.String)] G_M20911_IG06: 488BCE mov rcx, rsi 4885C9 test rcx, rcx 741F je SHORT G_M20911_IG09 48B830A9B604F97F0000 mov rax, 0x7FF904B6A930 ; System.String 483901 cmp qword ptr [rcx], rax 7510 jne SHORT G_M20911_IG09 48B9C09530808C020000 mov rcx, 0x28C803095C0 ; 'str!' FF154FC79000 call [System.Console:WriteLine(System.String)] G_M20911_IG09: FFC7 inc edi 83FF64 cmp edi, 100 7CAB jl SHORT G_M20911_IG03 ;; ========= loop end =========== 4883C428 add rsp, 40 5E pop rsi 5F pop rdi C3 ret ; Total bytes of code: 103 ``` Due to early expansion, we don't hoist and don't perform CSE for it. Expected codegen if we do the expansion in late phases: ```asm ; Method Prog:Foo(System.Object):this G_M20911_IG01: ;; offset=0000H 57 push rdi 56 push rsi 53 push rbx 4883EC20 sub rsp, 32 4885D2 test rdx, rdx 7413 je SHORT G_M20911_IG04 48B930A934F6F87F0000 mov rcx, 0x7FF8F634A930 ; System.String 33C0 xor rax, rax 48390A cmp qword ptr [rdx], rcx 480F45D0 cmovne rdx, rax G_M20911_IG04: ;; offset=001FH 33F6 xor esi, esi 4885D2 test rdx, rdx 400F95C6 setne sil 33FF xor edi, edi ;; ========= loop start ========= G_M20911_IG05: ;; offset=002AH 85F6 test esi, esi 741C je SHORT G_M20911_IG07 48BBC095200048020000 mov rbx, 0x248002095C0 ; 'str!' 488BCB mov rcx, rbx FF1567C79000 call [System.Console:WriteLine(System.String)] 488BCB mov rcx, rbx FF155EC79000 call [System.Console:WriteLine(System.String)] G_M20911_IG07: ;; offset=004AH FFC7 inc edi 83FF64 cmp edi, 100 7CD9 jl SHORT G_M20911_IG05 ;; ========= loop end =========== 4883C420 add rsp, 32 5B pop rbx 5E pop rsi 5F pop rdi C3 ret ; Total bytes of code: 89 ```
| Author: | EgorBo |
|---|---|
| Assignees: | - |
| Labels: | `area-CodeGen-coreclr` |
| Milestone: | - |
kunalspathak
Current codegen:
Due to early expansion, we don't hoist and don't perform CSE for it. Expected codegen if we do the expansion in late phases: