diff options
Diffstat (limited to 'src/cmd/compile/internal/abi/abiutils.go')
| -rw-r--r-- | src/cmd/compile/internal/abi/abiutils.go | 24 |
1 files changed, 15 insertions, 9 deletions
diff --git a/src/cmd/compile/internal/abi/abiutils.go b/src/cmd/compile/internal/abi/abiutils.go index 7573c13158..8495ed7c51 100644 --- a/src/cmd/compile/internal/abi/abiutils.go +++ b/src/cmd/compile/internal/abi/abiutils.go @@ -236,16 +236,22 @@ func (a *ABIParamAssignment) SpillOffset() int32 { return a.offset } -// FrameOffset returns the location that a value would spill to, if any exists. -// For register-allocated inputs, that is their spill offset reserved for morestack -// (might as well use it, it is there); for stack-allocated inputs and outputs, -// that is their location on the stack. For register-allocated outputs, there is -// no defined spill area, so return -1. +// FrameOffset returns the frame-pointer-relative location that a function +// would spill its input or output parameter to, if such a spill slot exists. +// For register-allocated inputs that is their spill offset reserved for morestack; +// for stack-allocated inputs and outputs, that is their location on the stack. +// For register-allocated outputs, there is no defined spill area, so return -1. +// (In a future version of the ABI, register-resident inputs may lose their defined +// spill area to help reduce stack sizes.) func (a *ABIParamAssignment) FrameOffset(i *ABIParamResultInfo) int64 { - if len(a.Registers) == 0 || a.offset == -1 { - return int64(a.offset) + if a.offset == -1 { + return -1 } - return int64(a.offset) + i.SpillAreaOffset() + if len(a.Registers) == 0 { // passed on stack + return int64(a.offset) - i.config.LocalsOffset() + } + // spill area for registers + return int64(a.offset) + i.SpillAreaOffset() - i.config.LocalsOffset() } // RegAmounts holds a specified number of integer/float registers. @@ -462,7 +468,7 @@ func (config *ABIConfig) updateOffset(result *ABIParamResultInfo, f *types.Field // Getting this wrong breaks stackmaps, see liveness/plive.go:WriteFuncMap and typebits/typebits.go:Set parameterUpdateMu.Lock() defer parameterUpdateMu.Unlock() - off := a.FrameOffset(result) - config.LocalsOffset() + 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. |