[NinoFloris]

Existing constrained call resolution refinements weren’t applied to static abstract interface methods: static calls were handled by an early-return path before reaching them. This moves that path after the refinements and extends the existing logic to handle static members where necessary.

This fixes #135168, and a few other deficiencies (see regression cases).

Tested on macOS arm64 Release, tiered compilation disabled. Before the change, all five static calls use a generic-dictionary lookup and an indirect call. Afterward, each implementation is inlined, with no lookup or call remaining.

Call	Case	Before	After	Inlined body
CallUnique	Original FuncImpl case	100 bytes	20 bytes	mov w0, w2 — return the tuple's integer field
CallExactGeneric	Exact generic struct, ExactGenericFunc<int>	84 bytes	20 bytes	add w0, w2, #5
CallDefault	Default interface implementation	84 bytes	20 bytes	mov w0, #7
CallCovariantUnique	Unique covariant interface implementation	60 bytes	28 bytes	Load the constant typeof(string) reference
CallGenericExact	Generic method with exact int argument	84 bytes	28 bytes	Load the constant typeof(int) reference

Address values shown as 0xD1FFAB1E are placeholders emitted by JitDisasmDiffable.

CallUnique: 100 → 20 bytes

Before:

G_M000_IG01:
            stp     fp, lr, [sp, #-0x30]!
            stp     x19, x20, [sp, #0x20]
            mov     fp, sp
            str     x0, [fp, #0x18]
            mov     x19, x1
            mov     w20, w2

G_M000_IG02:
            ldr     x1, [x0, #0x18]
            ldr     x2, [x1, #0x18]
            cbz     x2, G_M000_IG05

G_M000_IG03:
            mov     x0, x19
            mov     w1, w20
            blr     x2

G_M000_IG04:
            ldp     x19, x20, [sp, #0x20]
            ldp     fp, lr, [sp], #0x30
            ret     lr

G_M000_IG05:
            movz    x1, #0xD1FFAB1E
            movk    x1, #0xD1FFAB1E LSL #16
            movk    x1, #1 LSL #32
            movz    x2, #0xD1FFAB1E
            movk    x2, #0xD1FFAB1E LSL #16
            movk    x2, #1 LSL #32
            ldr     x2, [x2]
            blr     x2      // code for CORINFO_HELP_RUNTIMEHANDLE_METHOD
            mov     x2, x0
            b       G_M000_IG03

After:

G_M000_IG01:
            stp     fp, lr, [sp, #-0x10]!
            mov     fp, sp

G_M000_IG02:
            mov     w0, w2

G_M000_IG03:
            ldp     fp, lr, [sp], #0x10
            ret     lr

CallExactGeneric: 84 → 20 bytes

Before:

G_M000_IG01:
            stp     fp, lr, [sp, #-0x30]!
            stp     x19, x20, [sp, #0x20]
            mov     fp, sp
            str     x0, [fp, #0x18]
            mov     x19, x1
            mov     w20, w2

G_M000_IG02:
            ldr     x1, [x0, #0x18]
            ldr     x2, [x1, #0x18]
            cbz     x2, G_M000_IG05

G_M000_IG03:
            mov     x0, x19
            mov     w1, w20
            blr     x2

G_M000_IG04:
            ldp     x19, x20, [sp, #0x20]
            ldp     fp, lr, [sp], #0x30
            ret     lr

G_M000_IG05:
            movz    x1, #0xD1FFAB1E
            movk    x1, #0xD1FFAB1E LSL #16
            movk    x1, #1 LSL #32
            bl      CORINFO_HELP_RUNTIMEHANDLE_METHOD
            mov     x2, x0
            b       G_M000_IG03

After:

G_M000_IG01:
            stp     fp, lr, [sp, #-0x10]!
            mov     fp, sp

G_M000_IG02:
            add     w0, w2, #5

G_M000_IG03:
            ldp     fp, lr, [sp], #0x10
            ret     lr

CallDefault: 84 → 20 bytes

Before:

G_M000_IG01:
            stp     fp, lr, [sp, #-0x30]!
            stp     x19, x20, [sp, #0x20]
            mov     fp, sp
            str     x0, [fp, #0x18]
            mov     x19, x1
            mov     w20, w2

G_M000_IG02:
            ldr     x1, [x0, #0x18]
            ldr     x2, [x1, #0x18]
            cbz     x2, G_M000_IG05

G_M000_IG03:
            mov     x0, x19
            mov     w1, w20
            blr     x2

G_M000_IG04:
            ldp     x19, x20, [sp, #0x20]
            ldp     fp, lr, [sp], #0x30
            ret     lr

G_M000_IG05:
            movz    x1, #0xD1FFAB1E
            movk    x1, #0xD1FFAB1E LSL #16
            movk    x1, #1 LSL #32
            bl      CORINFO_HELP_RUNTIMEHANDLE_METHOD
            mov     x2, x0
            b       G_M000_IG03

After:

G_M000_IG01:
            stp     fp, lr, [sp, #-0x10]!
            mov     fp, sp

G_M000_IG02:
            mov     w0, #7

G_M000_IG03:
            ldp     fp, lr, [sp], #0x10
            ret     lr

CallCovariantUnique: 60 → 28 bytes

Before:

G_M000_IG01:
            stp     fp, lr, [sp, #-0x20]!
            mov     fp, sp
            str     x0, [fp, #0x18]

G_M000_IG02:
            ldr     x1, [x0, #0x18]
            ldr     x2, [x1, #0x18]
            cbz     x2, G_M000_IG05

G_M000_IG03:
            blr     x2

G_M000_IG04:
            ldp     fp, lr, [sp], #0x20
            ret     lr

G_M000_IG05:
            movz    x1, #0xD1FFAB1E
            movk    x1, #0xD1FFAB1E LSL #16
            movk    x1, #1 LSL #32
            bl      CORINFO_HELP_RUNTIMEHANDLE_METHOD
            mov     x2, x0
            b       G_M000_IG03

After:

G_M000_IG01:
            stp     fp, lr, [sp, #-0x10]!
            mov     fp, sp

G_M000_IG02:
            movz    x0, #0xD1FFAB1E
            movk    x0, #0xD1FFAB1E LSL #16
            movk    x0, #1 LSL #32

G_M000_IG03:
            ldp     fp, lr, [sp], #0x10
            ret     lr

CallGenericExact: 84 → 28 bytes

Before:

G_M000_IG01:
            stp     fp, lr, [sp, #-0x30]!
            stp     x19, x20, [sp, #0x20]
            mov     fp, sp
            str     x0, [fp, #0x18]
            mov     x19, x1
            mov     w20, w2

G_M000_IG02:
            ldr     x1, [x0, #0x18]
            ldr     x2, [x1, #0x20]
            cbz     x2, G_M000_IG05

G_M000_IG03:
            mov     x0, x19
            mov     w1, w20
            blr     x2

G_M000_IG04:
            ldp     x19, x20, [sp, #0x20]
            ldp     fp, lr, [sp], #0x30
            ret     lr

G_M000_IG05:
            movz    x1, #0xD1FFAB1E
            movk    x1, #0xD1FFAB1E LSL #16
            movk    x1, #1 LSL #32
            bl      CORINFO_HELP_RUNTIMEHANDLE_METHOD
            mov     x2, x0
            b       G_M000_IG03

After:

G_M000_IG01:
            stp     fp, lr, [sp, #-0x10]!
            mov     fp, sp

G_M000_IG02:
            movz    x0, #0xD1FFAB1E
            movk    x0, #0xD1FFAB1E LSL #16
            movk    x0, #1 LSL #32

G_M000_IG03:
            ldp     fp, lr, [sp], #0x10
            ret     lr

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[NinoFloris]

Failure is #134825

[NinoFloris]

Added another commit allowing target refinement for static abstract calls on reference types. Instance calls retain the existing restriction to value types. Static abstract calls now use the same target refinements for class targets.

The reason this is safe is that static abstract dispatch depends on the constrained type argument, not an object’s runtime type.

This is one part of improving static abstract performance in shared generics when the implementing type family is known (e.g. Node<T>, instantiated with string). We can identify the interface implementation even though the generic argument causes the code to be shared.

[NinoFloris]

@MihuBot