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[dev.regabi] cmd/compile: add code to support register ABI spills around morestack calls

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This is a selected copy from the register ABI experiment CL, focused
on the files and data structures that handle spilling around morestack.
Unnecessary code from the experiment was removed, other code was adapted.

Would it make sense to leave comments in the experiment as pieces are
brought over?

Experiment CL (for comparison purposes)
https://go-review.googlesource.com/c/go/+/28832

Change-Id: I92136f070351d4fcca1407b52ecf9b80898fed95
Reviewed-on: https://go-review.googlesource.com/c/go/+/279520
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
This commit is contained in:
David Chase 2020-09-28 17:42:30 -04:00
parent 2abd24f3b7
commit c1370e918f
4 changed files with 76 additions and 7 deletions
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44
src/cmd/internal/obj/link.go
View file

@ -766,6 +766,17 @@ type Auto struct {
Gotype *LSym
}
// RegArg provides spill/fill information for a register-resident argument
// to a function. These need spilling/filling in the safepoint/stackgrowth case.
// At the time of fill/spill, the offset must be adjusted by the architecture-dependent
// adjustment to hardware SP that occurs in a call instruction. E.g., for AMD64,
// at Offset+8 because the return address was pushed.
type RegArg struct {
Addr Addr
Reg int16
Spill, Unspill As
}
// Link holds the context for writing object code from a compiler
// to be linker input or for reading that input into the linker.
type Link struct {
@ -796,10 +807,11 @@ type Link struct {
DebugInfo func(fn *LSym, info *LSym, curfn interface{}) ([]dwarf.Scope, dwarf.InlCalls) // if non-nil, curfn is a *gc.Node
GenAbstractFunc func(fn *LSym)
Errors int
RegArgs []RegArg
InParallel bool // parallel backend phase in effect
UseBASEntries bool // use Base Address Selection Entries in location lists and PC ranges
IsAsm bool // is the source assembly language, which may contain surprising idioms (e.g., call tables)
InParallel bool // parallel backend phase in effect
UseBASEntries bool // use Base Address Selection Entries in location lists and PC ranges
IsAsm bool // is the source assembly language, which may contain surprising idioms (e.g., call tables)
// state for writing objects
Text []*LSym
@ -844,6 +856,32 @@ func (ctxt *Link) Logf(format string, args ...interface{}) {
ctxt.Bso.Flush()
}
func (ctxt *Link) SpillRegisterArgs(last *Prog, pa ProgAlloc) *Prog {
// Spill register args.
for _, ra := range ctxt.RegArgs {
spill := Appendp(last, pa)
spill.As = ra.Spill
spill.From.Type = TYPE_REG
spill.From.Reg = ra.Reg
spill.To = ra.Addr
last = spill
}
return last
}
func (ctxt *Link) UnspillRegisterArgs(last *Prog, pa ProgAlloc) *Prog {
// Unspill any spilled register args
for _, ra := range ctxt.RegArgs {
unspill := Appendp(last, pa)
unspill.As = ra.Unspill
unspill.From = ra.Addr
unspill.To.Type = TYPE_REG
unspill.To.Reg = ra.Reg
last = unspill
}
return last
}
// The smallest possible offset from the hardware stack pointer to a local
// variable on the stack. Architectures that use a link register save its value
// on the stack in the function prologue and so always have a pointer between