From ca2c99c0630645a43b6cd546c5dc74d0f8e8683f Mon Sep 17 00:00:00 2001 From: Simon Nattress Date: Wed, 4 Dec 2019 11:53:11 -0800 Subject: [PATCH] Remove overly eager devirtualization optimization Earlying out when `declMethod.OwningType == implType` is incorrect when the devirtualization manager resolves a call to `C2::M3` due to the presence of MethodImpls which redirect the slot (if a .override changes the slot, we bail on devirtualizing the call). In the example below (which is taken from https://github.com/dotnet/runtime/blob/859926f4c37158c683157bcd0f2b9d3c62d1f650/src/coreclr/tests/src/Loader/classloader/methodoverriding/regressions/576621/test.il#L10), `C2::M1` provides an override for `C1::M3` (which says the method body now comes from the virtual method `C2::M1`) which comes from a different vtable slot. ``` .class public C1 { .method public virtual instance int32 M1() { ldc.i4 1 ret } .method public virtual instance int32 M3() { ldc.i4 3 ret } } .class public C2 extends C1 { .method public virtual instance int32 M3() { ldc.i4 4 ret } .method public virtual instance int32 M1() { .override C1::M3 ldc.i4 5 ret } } ``` --- src/coreclr/src/tools/Common/Compiler/DevirtualizationManager.cs | 4 ---- 1 file changed, 4 deletions(-) diff --git a/src/coreclr/src/tools/Common/Compiler/DevirtualizationManager.cs b/src/coreclr/src/tools/Common/Compiler/DevirtualizationManager.cs index 92467d0..6191ebd 100644 --- a/src/coreclr/src/tools/Common/Compiler/DevirtualizationManager.cs +++ b/src/coreclr/src/tools/Common/Compiler/DevirtualizationManager.cs @@ -65,10 +65,6 @@ namespace ILCompiler protected virtual MethodDesc ResolveVirtualMethod(MethodDesc declMethod, DefType implType) { - // Quick check: if decl matches impl, we're done. - if (declMethod.OwningType == implType) - return declMethod; - MethodDesc impl; if (declMethod.OwningType.IsInterface) -- 2.7.4