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cmd/compile: do not change field offset in ABI analysis

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Currently, the ABI analysis assigns parameter/result offsets
to the fields of function *Type. In some cases, we may have
an ABI0 function reference and an ABIInternal reference share
the same function *Type. For example, for an ABI0 function F,
"f := F" will make f and (ABI0) F having the same *Type. But f,
as a func value, should use ABIInternal. Analyses on F and f will
collide and cause ICE.

Also, changing field offsets in ABI analysis has to be done very
carefully to avoid data races. It has been causing
trickiness/difficulty.

This CL removes the change of field offsets in ABI analysis
altogether. The analysis result is stored in ABIParamAssignment,
which is the only way to access parameter/result stack offset now.

Fixes #47317.
Fixes #47227.

Change-Id: I23a3e081a6cf327ac66855da222daaa636ed1ead
Reviewed-on: https://go-review.googlesource.com/c/go/+/336629
Trust: Cherry Mui <cherryyz@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Than McIntosh <thanm@google.com>
This commit is contained in:
Cherry Mui 2021-07-22 12:42:09 -04:00
parent 798ec73519
commit 052da5717e
5 changed files with 40 additions and 22 deletions
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21
src/cmd/compile/internal/abi/abiutils.go
View file

@ -446,35 +446,20 @@ func (config *ABIConfig) ABIAnalyze(t *types.Type, setNname bool) *ABIParamResul
return result
}
// parameterUpdateMu protects the Offset field of function/method parameters (a subset of structure Fields)
var parameterUpdateMu sync.Mutex
// FieldOffsetOf returns a concurrency-safe version of f.Offset
func FieldOffsetOf(f *types.Field) int64 {
parameterUpdateMu.Lock()
defer parameterUpdateMu.Unlock()
return f.Offset
}
func (config *ABIConfig) updateOffset(result *ABIParamResultInfo, f *types.Field, a ABIParamAssignment, isReturn, setNname bool) {
// Everything except return values in registers has either a frame home (if not in a register) or a frame spill location.
if !isReturn || len(a.Registers) == 0 {
// The type frame offset DOES NOT show effects of minimum frame size.
// Getting this wrong breaks stackmaps, see liveness/plive.go:WriteFuncMap and typebits/typebits.go:Set
parameterUpdateMu.Lock()
defer parameterUpdateMu.Unlock()
off := a.FrameOffset(result)
fOffset := f.Offset
if fOffset == types.BOGUS_FUNARG_OFFSET {
// Set the Offset the first time. After that, we may recompute it, but it should never change.
f.Offset = off
if f.Nname != nil {
// always set it in this case.
if setNname && f.Nname != nil {
f.Nname.(*ir.Name).SetFrameOffset(off)
f.Nname.(*ir.Name).SetIsOutputParamInRegisters(false)
}
} else if fOffset != off {
base.Fatalf("offset for %s at %s changed from %d to %d", f.Sym.Name, base.FmtPos(f.Pos), fOffset, off)
} else {
base.Fatalf("field offset for %s at %s has been set to %d", f.Sym.Name, base.FmtPos(f.Pos), fOffset)
}
} else {
if setNname && f.Nname != nil {