JIT: reduce importer spilling for some stfld #51158
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If we know which local is going to be updated, just spill that local.
dotnet-issue-labeler
bot
added
the
area-CodeGen-coreclr
|
Inspired by this example using System;
using System.Runtime.CompilerServices;
public struct StructField<T>
{
public T Value;
}
class X
{
static volatile int value;
[MethodImpl(MethodImplOptions.NoInlining)]
public void StructOfStructOfField1()
{
var x = new StructField<StructField<int>> { Value = new StructField<int> { Value = 123 } };
value = x.Value.Value;
}
}Old codegen was: G_M12726_IG01:
push rax
xor eax, eax
mov qword ptr [rsp], rax
;; bbWeight=1 PerfScore 2.25
G_M12726_IG02:
lea rax, bword ptr [rsp]
mov dword ptr [rax], 123
mov eax, dword ptr [rsp]
mov dword ptr [reloc classVar[0xd1ffab1e]], eax
;; bbWeight=1 PerfScore 3.50
G_M12726_IG03:
add rsp, 8
ret
New codegen is G_M12726_IG01:
;; bbWeight=1 PerfScore 0.00
G_M12726_IG02:
mov dword ptr [reloc classVar[0xd1ffab1e]], 123
;; bbWeight=1 PerfScore 1.00
G_M12726_IG03:
ret
@sandreeko PTAL Detail diffsDetail diffsDetail diffsDetail diffsDetail diffs |
|
fyi @stephentoub, still apparently simple. |
sandreenko
approved these changes
Apr 14, 2021
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If we know which local is going to be updated, just spill that local.