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[dev.typeparams] cmd/compile, runtime: simplify opendefer metadata

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Now that deferred functions are always argumentless, we don't
need the metadata for the frame size, number of arguments, and
the information about each argument.

Change-Id: I99e75248a22bda6efbdf2012a2f35beca4c18fd7
Reviewed-on: https://go-review.googlesource.com/c/go/+/326061
Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
This commit is contained in:
Cherry Mui 2021-06-08 18:07:16 -04:00
parent c0a86c10f1
commit b20747334a
2 changed files with 2 additions and 37 deletions
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22
src/cmd/compile/internal/ssagen/ssa.go
View File

@ -324,43 +324,21 @@ func dvarint(x *obj.LSym, off int, v int64) int {
// for stack variables are specified as the number of bytes below varp (pointer to the
// top of the local variables) for their starting address. The format is:
//
// - Max total argument size among all the defers
// - Offset of the deferBits variable
// - Number of defers in the function
// - Information about each defer call, in reverse order of appearance in the function:
// - Total argument size of the call
// - Offset of the closure value to call
// - Number of arguments (including interface receiver or method receiver as first arg)
// - Information about each argument
// - Offset of the stored defer argument in this function's frame
// - Size of the argument
// - Offset of where argument should be placed in the args frame when making call
func (s *state) emitOpenDeferInfo() {
x := base.Ctxt.Lookup(s.curfn.LSym.Name + ".opendefer")
s.curfn.LSym.Func().OpenCodedDeferInfo = x
off := 0
// Compute maxargsize (max size of arguments for all defers)
// first, so we can output it first to the funcdata
var maxargsize int64
for i := len(s.openDefers) - 1; i >= 0; i-- {
r := s.openDefers[i]
argsize := r.n.X.Type().ArgWidth() // TODO register args: but maybe use of abi0 will make this easy
if argsize > maxargsize {
maxargsize = argsize
}
}
off = dvarint(x, off, maxargsize)
off = dvarint(x, off, -s.deferBitsTemp.FrameOffset())
off = dvarint(x, off, int64(len(s.openDefers)))
// Write in reverse-order, for ease of running in that order at runtime
for i := len(s.openDefers) - 1; i >= 0; i-- {
r := s.openDefers[i]
off = dvarint(x, off, r.n.X.Type().ArgWidth())
off = dvarint(x, off, -r.closureNode.FrameOffset())
numArgs := 0
off = dvarint(x, off, int64(numArgs))
}
}

17
src/runtime/panic.go
View File

@ -720,8 +720,7 @@ func addOneOpenDeferFrame(gp *g, pc uintptr, sp unsafe.Pointer) {
throw("missing deferreturn")
}
maxargsize, _ := readvarintUnsafe(fd)
d1 := newdefer(int32(maxargsize))
d1 := newdefer(0)
d1.openDefer = true
d1._panic = nil
// These are the pc/sp to set after we've
@ -782,27 +781,15 @@ func runOpenDeferFrame(gp *g, d *_defer) bool {
done := true
fd := d.fd
// Skip the maxargsize
_, fd = readvarintUnsafe(fd)
deferBitsOffset, fd := readvarintUnsafe(fd)
nDefers, fd := readvarintUnsafe(fd)
deferBits := *(*uint8)(unsafe.Pointer(d.varp - uintptr(deferBitsOffset)))
for i := int(nDefers) - 1; i >= 0; i-- {
// read the funcdata info for this defer
var argWidth, closureOffset, nArgs uint32
argWidth, fd = readvarintUnsafe(fd)
var closureOffset uint32
closureOffset, fd = readvarintUnsafe(fd)
nArgs, fd = readvarintUnsafe(fd)
if argWidth != 0 || nArgs != 0 {
throw("defer with non-empty frame")
}
if deferBits&(1<<i) == 0 {
for j := uint32(0); j < nArgs; j++ {
_, fd = readvarintUnsafe(fd)
_, fd = readvarintUnsafe(fd)
_, fd = readvarintUnsafe(fd)
}
continue
}
closure := *(*func())(unsafe.Pointer(d.varp - uintptr(closureOffset)))