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cmd/compile,cmd/link: introduce generic interface call relocations
To capture the fact that a method was called on a generic interface, so we can make sure the linker doesn't throw away any implementations that might be the method called. See the comment in reflect.go for details. Fixes #49049 Change-Id: I0be74b6e727c1ecefedae072b149f59d539dc1e9 Reviewed-on: https://go-review.googlesource.com/c/go/+/357835 Trust: Keith Randall <khr@golang.org> Trust: Dan Scales <danscales@google.com> Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Cherry Mui <cherryyz@google.com> Reviewed-by: Dan Scales <danscales@google.com> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
This commit is contained in:
Keith Randall
parent
252324e879
commit
c26a32a500
@ -18,6 +18,7 @@ import (
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"cmd/compile/internal/inline"
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"cmd/compile/internal/ir"
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"cmd/compile/internal/objw"
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"cmd/compile/internal/staticdata"
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"cmd/compile/internal/typebits"
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"cmd/compile/internal/typecheck"
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"cmd/compile/internal/types"
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@ -1995,8 +1996,33 @@ func MarkUsedIfaceMethod(n *ir.CallExpr) {
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dot := n.X.(*ir.SelectorExpr)
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ityp := dot.X.Type()
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if ityp.HasShape() {
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base.Fatalf("marking method of shape type used %+v %s", ityp, dot.Sel.Name)
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// Here we're calling a method on a generic interface. Something like:
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//
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// type I[T any] interface { foo() T }
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// func f[T any](x I[T]) {
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// ... = x.foo()
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// }
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// f[int](...)
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// f[string](...)
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//
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// In this case, in f we're calling foo on a generic interface.
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// Which method could that be? Normally we could match the method
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// both by name and by type. But in this case we don't really know
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// the type of the method we're calling. It could be func()int
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// or func()string. So we match on just the function name, instead
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// of both the name and the type used for the non-generic case below.
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// TODO: instantiations at least know the shape of the instantiated
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// type, and the linker could do more complicated matching using
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// some sort of fuzzy shape matching. For now, only use the name
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// of the method for matching.
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r := obj.Addrel(ir.CurFunc.LSym)
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// We use a separate symbol just to tell the linker the method name.
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// (The symbol itself is not needed in the final binary.)
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r.Sym = staticdata.StringSym(src.NoXPos, dot.Sel.Name)
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r.Type = objabi.R_USEGENERICIFACEMETHOD
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return
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}
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tsym := TypeLinksym(ityp)
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r := obj.Addrel(ir.CurFunc.LSym)
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r.Sym = tsym
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@ -506,17 +506,7 @@ func walkCall(n *ir.CallExpr, init *ir.Nodes) ir.Node {
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usemethod(n)
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}
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if n.Op() == ir.OCALLINTER {
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if n.X.(*ir.SelectorExpr).X.Type().HasShape() {
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// There should be an entry in n.KeepAlive to keep the
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// dictionary alive (added in ../noder/transformCall).
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// The dictionary in turn marks the method as used.
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if len(n.KeepAlive) == 0 {
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// TODO(khr): this fails for issue44688.go.
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//base.Fatalf("KeepAlive of dictionary arg missing")
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}
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} else {
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reflectdata.MarkUsedIfaceMethod(n)
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}
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reflectdata.MarkUsedIfaceMethod(n)
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}
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if n.Op() == ir.OCALLFUNC && n.X.Op() == ir.OCLOSURE {
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@ -93,6 +93,11 @@ const (
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// This is a marker relocation (0-sized), for the linker's reachabililty
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// analysis.
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R_USEIFACEMETHOD
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// Similar to R_USEIFACEMETHOD, except instead of indicating a type +
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// method offset with Sym+Add, Sym points to a symbol containing the name
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// of the method being called. See the description in
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// cmd/compile/internal/reflectdata/reflect.go:MarkUsedIfaceMethod for details.
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R_USEGENERICIFACEMETHOD
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// R_METHODOFF resolves to a 32-bit offset from the beginning of the section
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// holding the data being relocated to the referenced symbol.
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// It is a variant of R_ADDROFF used when linking from the uncommonType of a
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@ -32,48 +32,49 @@ func _() {
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_ = x[R_USETYPE-22]
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_ = x[R_USEIFACE-23]
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_ = x[R_USEIFACEMETHOD-24]
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_ = x[R_METHODOFF-25]
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_ = x[R_KEEP-26]
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_ = x[R_POWER_TOC-27]
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_ = x[R_GOTPCREL-28]
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_ = x[R_JMPMIPS-29]
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_ = x[R_DWARFSECREF-30]
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_ = x[R_DWARFFILEREF-31]
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_ = x[R_ARM64_TLS_LE-32]
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_ = x[R_ARM64_TLS_IE-33]
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_ = x[R_ARM64_GOTPCREL-34]
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_ = x[R_ARM64_GOT-35]
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_ = x[R_ARM64_PCREL-36]
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_ = x[R_ARM64_LDST8-37]
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_ = x[R_ARM64_LDST16-38]
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_ = x[R_ARM64_LDST32-39]
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_ = x[R_ARM64_LDST64-40]
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_ = x[R_ARM64_LDST128-41]
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_ = x[R_POWER_TLS_LE-42]
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_ = x[R_POWER_TLS_IE-43]
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_ = x[R_POWER_TLS-44]
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_ = x[R_ADDRPOWER_DS-45]
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_ = x[R_ADDRPOWER_GOT-46]
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_ = x[R_ADDRPOWER_PCREL-47]
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_ = x[R_ADDRPOWER_TOCREL-48]
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_ = x[R_ADDRPOWER_TOCREL_DS-49]
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_ = x[R_RISCV_CALL-50]
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_ = x[R_RISCV_CALL_TRAMP-51]
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_ = x[R_RISCV_PCREL_ITYPE-52]
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_ = x[R_RISCV_PCREL_STYPE-53]
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_ = x[R_RISCV_TLS_IE_ITYPE-54]
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_ = x[R_RISCV_TLS_IE_STYPE-55]
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_ = x[R_PCRELDBL-56]
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_ = x[R_ADDRMIPSU-57]
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_ = x[R_ADDRMIPSTLS-58]
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_ = x[R_ADDRCUOFF-59]
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_ = x[R_WASMIMPORT-60]
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_ = x[R_XCOFFREF-61]
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_ = x[R_USEGENERICIFACEMETHOD-25]
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_ = x[R_METHODOFF-26]
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_ = x[R_KEEP-27]
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_ = x[R_POWER_TOC-28]
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_ = x[R_GOTPCREL-29]
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_ = x[R_JMPMIPS-30]
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_ = x[R_DWARFSECREF-31]
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_ = x[R_DWARFFILEREF-32]
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_ = x[R_ARM64_TLS_LE-33]
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_ = x[R_ARM64_TLS_IE-34]
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_ = x[R_ARM64_GOTPCREL-35]
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_ = x[R_ARM64_GOT-36]
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_ = x[R_ARM64_PCREL-37]
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_ = x[R_ARM64_LDST8-38]
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_ = x[R_ARM64_LDST16-39]
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_ = x[R_ARM64_LDST32-40]
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_ = x[R_ARM64_LDST64-41]
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_ = x[R_ARM64_LDST128-42]
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_ = x[R_POWER_TLS_LE-43]
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_ = x[R_POWER_TLS_IE-44]
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_ = x[R_POWER_TLS-45]
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_ = x[R_ADDRPOWER_DS-46]
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_ = x[R_ADDRPOWER_GOT-47]
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_ = x[R_ADDRPOWER_PCREL-48]
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_ = x[R_ADDRPOWER_TOCREL-49]
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_ = x[R_ADDRPOWER_TOCREL_DS-50]
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_ = x[R_RISCV_CALL-51]
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_ = x[R_RISCV_CALL_TRAMP-52]
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_ = x[R_RISCV_PCREL_ITYPE-53]
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_ = x[R_RISCV_PCREL_STYPE-54]
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_ = x[R_RISCV_TLS_IE_ITYPE-55]
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_ = x[R_RISCV_TLS_IE_STYPE-56]
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_ = x[R_PCRELDBL-57]
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_ = x[R_ADDRMIPSU-58]
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_ = x[R_ADDRMIPSTLS-59]
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_ = x[R_ADDRCUOFF-60]
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_ = x[R_WASMIMPORT-61]
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_ = x[R_XCOFFREF-62]
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}
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const _RelocType_name = "R_ADDRR_ADDRPOWERR_ADDRARM64R_ADDRMIPSR_ADDROFFR_SIZER_CALLR_CALLARMR_CALLARM64R_CALLINDR_CALLPOWERR_CALLMIPSR_CONSTR_PCRELR_TLS_LER_TLS_IER_GOTOFFR_PLT0R_PLT1R_PLT2R_USEFIELDR_USETYPER_USEIFACER_USEIFACEMETHODR_METHODOFFR_KEEPR_POWER_TOCR_GOTPCRELR_JMPMIPSR_DWARFSECREFR_DWARFFILEREFR_ARM64_TLS_LER_ARM64_TLS_IER_ARM64_GOTPCRELR_ARM64_GOTR_ARM64_PCRELR_ARM64_LDST8R_ARM64_LDST16R_ARM64_LDST32R_ARM64_LDST64R_ARM64_LDST128R_POWER_TLS_LER_POWER_TLS_IER_POWER_TLSR_ADDRPOWER_DSR_ADDRPOWER_GOTR_ADDRPOWER_PCRELR_ADDRPOWER_TOCRELR_ADDRPOWER_TOCREL_DSR_RISCV_CALLR_RISCV_CALL_TRAMPR_RISCV_PCREL_ITYPER_RISCV_PCREL_STYPER_RISCV_TLS_IE_ITYPER_RISCV_TLS_IE_STYPER_PCRELDBLR_ADDRMIPSUR_ADDRMIPSTLSR_ADDRCUOFFR_WASMIMPORTR_XCOFFREF"
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const _RelocType_name = "R_ADDRR_ADDRPOWERR_ADDRARM64R_ADDRMIPSR_ADDROFFR_SIZER_CALLR_CALLARMR_CALLARM64R_CALLINDR_CALLPOWERR_CALLMIPSR_CONSTR_PCRELR_TLS_LER_TLS_IER_GOTOFFR_PLT0R_PLT1R_PLT2R_USEFIELDR_USETYPER_USEIFACER_USEIFACEMETHODR_USEGENERICIFACEMETHODR_METHODOFFR_KEEPR_POWER_TOCR_GOTPCRELR_JMPMIPSR_DWARFSECREFR_DWARFFILEREFR_ARM64_TLS_LER_ARM64_TLS_IER_ARM64_GOTPCRELR_ARM64_GOTR_ARM64_PCRELR_ARM64_LDST8R_ARM64_LDST16R_ARM64_LDST32R_ARM64_LDST64R_ARM64_LDST128R_POWER_TLS_LER_POWER_TLS_IER_POWER_TLSR_ADDRPOWER_DSR_ADDRPOWER_GOTR_ADDRPOWER_PCRELR_ADDRPOWER_TOCRELR_ADDRPOWER_TOCREL_DSR_RISCV_CALLR_RISCV_CALL_TRAMPR_RISCV_PCREL_ITYPER_RISCV_PCREL_STYPER_RISCV_TLS_IE_ITYPER_RISCV_TLS_IE_STYPER_PCRELDBLR_ADDRMIPSUR_ADDRMIPSTLSR_ADDRCUOFFR_WASMIMPORTR_XCOFFREF"
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var _RelocType_index = [...]uint16{0, 6, 17, 28, 38, 47, 53, 59, 68, 79, 88, 99, 109, 116, 123, 131, 139, 147, 153, 159, 165, 175, 184, 194, 210, 221, 227, 238, 248, 257, 270, 284, 298, 312, 328, 339, 352, 365, 379, 393, 407, 422, 436, 450, 461, 475, 490, 507, 525, 546, 558, 576, 595, 614, 634, 654, 664, 675, 688, 699, 711, 721}
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var _RelocType_index = [...]uint16{0, 6, 17, 28, 38, 47, 53, 59, 68, 79, 88, 99, 109, 116, 123, 131, 139, 147, 153, 159, 165, 175, 184, 194, 210, 233, 244, 250, 261, 271, 280, 293, 307, 321, 335, 351, 362, 375, 388, 402, 416, 430, 445, 459, 473, 484, 498, 513, 530, 548, 569, 581, 599, 618, 637, 657, 677, 687, 698, 711, 722, 734, 744}
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func (i RelocType) String() string {
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i -= 1
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@ -22,10 +22,11 @@ type deadcodePass struct {
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ldr *loader.Loader
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wq heap // work queue, using min-heap for better locality
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ifaceMethod map[methodsig]bool // methods declared in reached interfaces
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markableMethods []methodref // methods of reached types
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reflectSeen bool // whether we have seen a reflect method call
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dynlink bool
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ifaceMethod map[methodsig]bool // methods called from reached interface call sites
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genericIfaceMethod map[string]bool // names of methods called from reached generic interface call sites
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markableMethods []methodref // methods of reached types
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reflectSeen bool // whether we have seen a reflect method call
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dynlink bool
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methodsigstmp []methodsig // scratch buffer for decoding method signatures
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}
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@ -33,6 +34,7 @@ type deadcodePass struct {
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func (d *deadcodePass) init() {
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d.ldr.InitReachable()
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d.ifaceMethod = make(map[methodsig]bool)
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d.genericIfaceMethod = make(map[string]bool)
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if buildcfg.Experiment.FieldTrack {
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d.ldr.Reachparent = make([]loader.Sym, d.ldr.NSym())
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}
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@ -197,6 +199,13 @@ func (d *deadcodePass) flood() {
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}
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d.ifaceMethod[m] = true
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continue
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case objabi.R_USEGENERICIFACEMETHOD:
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name := d.decodeGenericIfaceMethod(d.ldr, r.Sym())
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if d.ctxt.Debugvlog > 1 {
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d.ctxt.Logf("reached generic iface method: %s\n", name)
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}
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d.genericIfaceMethod[name] = true
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continue // don't mark referenced symbol - it is not needed in the final binary.
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}
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rs := r.Sym()
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if isgotype && usedInIface && d.ldr.IsGoType(rs) && !d.ldr.AttrUsedInIface(rs) {
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@ -352,7 +361,7 @@ func deadcode(ctxt *Link) {
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// in the last pass.
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rem := d.markableMethods[:0]
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for _, m := range d.markableMethods {
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if (d.reflectSeen && m.isExported()) || d.ifaceMethod[m.m] {
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if (d.reflectSeen && m.isExported()) || d.ifaceMethod[m.m] || d.genericIfaceMethod[m.m.name] {
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d.markMethod(m)
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} else {
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rem = append(rem, m)
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@ -425,6 +434,11 @@ func (d *deadcodePass) decodeIfaceMethod(ldr *loader.Loader, arch *sys.Arch, sym
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return m
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}
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// Decode the method name stored in symbol symIdx. The symbol should contain just the bytes of a method name.
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func (d *deadcodePass) decodeGenericIfaceMethod(ldr *loader.Loader, symIdx loader.Sym) string {
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return string(ldr.Data(symIdx))
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}
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func (d *deadcodePass) decodetypeMethods(ldr *loader.Loader, arch *sys.Arch, symIdx loader.Sym, relocs *loader.Relocs) []methodsig {
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p := ldr.Data(symIdx)
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if !decodetypeHasUncommon(arch, p) {
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27
test/typeparam/issue49049.go
Normal file
27
test/typeparam/issue49049.go
Normal file
@ -0,0 +1,27 @@
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// run -gcflags=-G=3
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// Copyright 2021 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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type A[T any] interface {
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m()
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}
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type Z struct {
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a,b int
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}
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func (z *Z) m() {
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}
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func test[T any]() {
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var a A[T] = &Z{}
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f := a.m
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f()
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}
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func main() {
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test[string]()
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}
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