cmd/internal/obj: fix pc/sp information for prologue
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>
diff --git a/src/cmd/internal/obj/arm/obj5.go b/src/cmd/internal/obj/arm/obj5.go
index ce1cad9..15534e6 100644
--- a/src/cmd/internal/obj/arm/obj5.go
+++ b/src/cmd/internal/obj/arm/obj5.go
@@ -804,8 +804,12 @@
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 @@
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
}
diff --git a/src/cmd/internal/obj/arm64/obj7.go b/src/cmd/internal/obj/arm64/obj7.go
index 77117fb..91088c1 100644
--- a/src/cmd/internal/obj/arm64/obj7.go
+++ b/src/cmd/internal/obj/arm64/obj7.go
@@ -161,8 +161,12 @@
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 @@
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
diff --git a/src/cmd/internal/obj/x86/obj6.go b/src/cmd/internal/obj/x86/obj6.go
index fa9c474..5ee097e 100644
--- a/src/cmd/internal/obj/x86/obj6.go
+++ b/src/cmd/internal/obj/x86/obj6.go
@@ -975,7 +975,12 @@
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 @@
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
