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cmd/compile: use cache in front of convI2I

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This is the last of the getitab users to receive a cache.
We should now no longer see getitab (and callees) in profiles.
Hopefully.

Change-Id: I2ed72b9943095bbe8067c805da7f08e00706c98c
Reviewed-on: https://go-review.googlesource.com/c/go/+/531055
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Keith Randall 2023-09-25 13:42:19 -07:00
parent 7fcc626b57
commit afd7c15c7f
6 changed files with 293 additions and 278 deletions
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35
src/cmd/compile/internal/walk/expr.go
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@ -726,25 +726,30 @@ func walkDotType(n *ir.TypeAssertExpr, init *ir.Nodes) ir.Node {
n.ITab = reflectdata.ITabAddrAt(base.Pos, n.Type(), n.X.Type())
}
if n.X.Type().IsInterface() && n.Type().IsInterface() && !n.Type().IsEmptyInterface() {
// Converting an interface to a non-empty interface. Needs a runtime call.
// Allocate an internal/abi.TypeAssert descriptor for that call.
lsym := types.LocalPkg.Lookup(fmt.Sprintf(".typeAssert.%d", typeAssertGen)).LinksymABI(obj.ABI0)
typeAssertGen++
off := 0
off = objw.SymPtr(lsym, off, typecheck.LookupRuntimeVar("emptyTypeAssertCache"), 0)
off = objw.SymPtr(lsym, off, reflectdata.TypeSym(n.Type()).Linksym(), 0)
off = objw.Bool(lsym, off, n.Op() == ir.ODOTTYPE2) // CanFail
off += types.PtrSize - 1
objw.Global(lsym, int32(off), obj.LOCAL)
// Set the type to be just a single pointer, as the cache pointer is the
// only one that GC needs to see.
lsym.Gotype = reflectdata.TypeLinksym(types.Types[types.TUINT8].PtrTo())
n.Descriptor = lsym
// This kind of conversion needs a runtime call. Allocate
// a descriptor for that call.
n.Descriptor = makeTypeAssertDescriptor(n.Type(), n.Op() == ir.ODOTTYPE2)
}
return n
}
func makeTypeAssertDescriptor(target *types.Type, canFail bool) *obj.LSym {
// When converting from an interface to a non-empty interface. Needs a runtime call.
// Allocate an internal/abi.TypeAssert descriptor for that call.
lsym := types.LocalPkg.Lookup(fmt.Sprintf(".typeAssert.%d", typeAssertGen)).LinksymABI(obj.ABI0)
typeAssertGen++
off := 0
off = objw.SymPtr(lsym, off, typecheck.LookupRuntimeVar("emptyTypeAssertCache"), 0)
off = objw.SymPtr(lsym, off, reflectdata.TypeSym(target).Linksym(), 0)
off = objw.Bool(lsym, off, canFail)
off += types.PtrSize - 1
objw.Global(lsym, int32(off), obj.LOCAL)
// Set the type to be just a single pointer, as the cache pointer is the
// only one that GC needs to see.
lsym.Gotype = reflectdata.TypeLinksym(types.Types[types.TUINT8].PtrTo())
return lsym
}
var typeAssertGen int
// walkDynamicDotType walks an ODYNAMICDOTTYPE or ODYNAMICDOTTYPE2 node.