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cmd/compile: use getcallersp for gorecover "fp" arg

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Currently, the compiler synthesize a special ".fp" node, which
points to the FP of the current frame, be to used to call
gorecover. Later that node turns to an Arg in SSA that is not
really an arg, causing problems for the new ABI work which changes
the handling of Args, so we have to special-case that node.

This CL changes the compiler to get the FP by using getcallersp,
which is an intrinsic in SSA and works on all platforms. As we
need the FP, not the caller SP, one drawback is that we have to
add FixedFrameSize for LR machines. But it does allow us to remove
that special node.

Change-Id: Ie721d51efca8116c9d23cc4f79738fffcf847df8
Reviewed-on: https://go-review.googlesource.com/c/go/+/297930
Trust: Cherry Zhang <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>
This commit is contained in:
Cherry Zhang 2021-03-02 10:27:18 -05:00
parent a22bd3dc73
commit fb03be9d55
7 changed files with 11 additions and 18 deletions
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2
src/cmd/compile/internal/ir/name.go
View File

@ -509,5 +509,3 @@ func NewPkgName(pos src.XPos, sym *types.Sym, pkg *types.Pkg) *PkgName {
p.pos = pos
return p
}
var RegFP *Name

7
src/cmd/compile/internal/ssagen/pgen.go
View File

@ -93,12 +93,7 @@ func (s *ssafn) AllocFrame(f *ssa.Func) {
for _, v := range b.Values {
if n, ok := v.Aux.(*ir.Name); ok {
switch n.Class {
case ir.PPARAM, ir.PPARAMOUT:
// Don't modify RegFP; it is a global.
if n != ir.RegFP {
n.SetUsed(true)
}
case ir.PAUTO:
case ir.PPARAM, ir.PPARAMOUT, ir.PAUTO:
n.SetUsed(true)
}
}

4
src/cmd/compile/internal/ssagen/ssa.go
View File

@ -5176,10 +5176,6 @@ func (s *state) addr(n ir.Node) *ssa.Value {
if v != nil {
return v
}
if n == ir.RegFP {
// Special arg that points to the frame pointer (Used by ORECOVER).
return s.entryNewValue2A(ssa.OpLocalAddr, t, n, s.sp, s.startmem)
}
s.Fatalf("addr of undeclared ONAME %v. declared: %v", n, s.decladdrs)
return nil
case ir.PAUTO:

1
src/cmd/compile/internal/typecheck/builtin.go
View File

@ -178,6 +178,7 @@ var runtimeDecls = [...]struct {
{"uint32tofloat64", funcTag, 117},
{"complex128div", funcTag, 118},
{"getcallerpc", funcTag, 119},
{"getcallersp", funcTag, 119},
{"racefuncenter", funcTag, 31},
{"racefuncexit", funcTag, 9},
{"raceread", funcTag, 31},

1
src/cmd/compile/internal/typecheck/builtin/runtime.go
View File

@ -226,6 +226,7 @@ func uint32tofloat64(uint32) float64
func complex128div(num complex128, den complex128) (quo complex128)
func getcallerpc() uintptr
func getcallersp() uintptr
// race detection
func racefuncenter(uintptr)

5
src/cmd/compile/internal/typecheck/universe.go
View File

@ -354,9 +354,4 @@ func DeclareUniverse() {
s1.Def = s.Def
s1.Block = s.Block
}
ir.RegFP = NewName(Lookup(".fp"))
ir.RegFP.SetType(types.Types[types.TINT32])
ir.RegFP.Class = ir.PPARAM
ir.RegFP.SetUsed(true)
}

9
src/cmd/compile/internal/walk/expr.go
View File

@ -158,7 +158,14 @@ func walkExpr1(n ir.Node, init *ir.Nodes) ir.Node {
case ir.ORECOVER:
n := n.(*ir.CallExpr)
return mkcall("gorecover", n.Type(), init, typecheck.NodAddr(ir.RegFP))
// Call gorecover with the FP of this frame.
// FP is equal to caller's SP plus FixedFrameSize().
var fp ir.Node = mkcall("getcallersp", types.Types[types.TUINTPTR], init)
if off := base.Ctxt.FixedFrameSize(); off != 0 {
fp = ir.NewBinaryExpr(fp.Pos(), ir.OADD, fp, ir.NewInt(off))
}
fp = ir.NewConvExpr(fp.Pos(), ir.OCONVNOP, types.NewPtr(types.Types[types.TINT32]), fp)
return mkcall("gorecover", n.Type(), init, fp)
case ir.OCFUNC:
return n