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cmd/internal/obj: fix pc/sp information for prologue

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When the prologue call to morestack was moved down to the
bottom of the function, the pc/sp tables were not updated.
If a traceback through a call to morestack is needed, it would
get confused at and stop at morestack.

Confirmed the fix by adding //go:systemstack (which calls
morestackc, but same issue) where it did not belong
and inspecting the crash.

Change-Id: Id0294bb9dba51ef1a49154637228fb57f1086a94
Reviewed-on: https://go-review.googlesource.com/12144
Reviewed-by: Rob Pike <r@golang.org>
This commit is contained in:
Russ Cox 2015-07-13 21:21:49 -04:00
parent 0c72eeb121
commit 0a3c991fd3
3 changed files with 28 additions and 3 deletions
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10
src/cmd/internal/obj/arm/obj5.go
View file

@ -804,8 +804,12 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32) *obj.Prog {
for last = ctxt.Cursym.Text; last.Link != nil; last = last.Link {
}
spfix := obj.Appendp(ctxt, last)
spfix.As = obj.ANOP
spfix.Spadj = -framesize
// MOVW LR, R3
movw := obj.Appendp(ctxt, last)
movw := obj.Appendp(ctxt, spfix)
movw.As = AMOVW
movw.From.Type = obj.TYPE_REG
movw.From.Reg = REGLINK
@ -833,6 +837,10 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32) *obj.Prog {
b.To.Type = obj.TYPE_BRANCH
b.Pcond = ctxt.Cursym.Text.Link
spfix = obj.Appendp(ctxt, b)
spfix.As = obj.ANOP
spfix.Spadj = +framesize
return bls
}

10
src/cmd/internal/obj/arm64/obj7.go
View file

@ -161,8 +161,12 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32) *obj.Prog {
for last = ctxt.Cursym.Text; last.Link != nil; last = last.Link {
}
spfix := obj.Appendp(ctxt, last)
spfix.As = obj.ANOP
spfix.Spadj = -framesize
// MOV LR, R3
movlr := obj.Appendp(ctxt, last)
movlr := obj.Appendp(ctxt, spfix)
movlr.As = AMOVD
movlr.From.Type = obj.TYPE_REG
movlr.From.Reg = REGLINK
@ -202,6 +206,10 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32) *obj.Prog {
jmp.To.Type = obj.TYPE_BRANCH
jmp.Pcond = ctxt.Cursym.Text.Link
spfix = obj.Appendp(ctxt, jmp)
spfix.As = obj.ANOP
spfix.Spadj = +framesize
// placeholder for bls's jump target
// p = obj.Appendp(ctxt, p)
// p.As = obj.ANOP

11
src/cmd/internal/obj/x86/obj6.go
View file

@ -975,7 +975,12 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32, textarg int32) *ob
for last = ctxt.Cursym.Text; last.Link != nil; last = last.Link {
}
call := obj.Appendp(ctxt, last)
// Explain to PC-line tables that there is no frame here.
spfix := obj.Appendp(ctxt, last)
spfix.As = obj.ANOP
spfix.Spadj = -framesize
call := obj.Appendp(ctxt, spfix)
call.Lineno = ctxt.Cursym.Text.Lineno
call.Mode = ctxt.Cursym.Text.Mode
call.As = obj.ACALL
@ -994,6 +999,10 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32, textarg int32) *ob
jmp.To.Type = obj.TYPE_BRANCH
jmp.Pcond = ctxt.Cursym.Text.Link
spfix = obj.Appendp(ctxt, jmp)
spfix.As = obj.ANOP
spfix.Spadj = +framesize
jls.Pcond = call
if q1 != nil {
q1.Pcond = call