cmd/compile: remove more dead code and data structures

Remove more now-redundant code, methods, and types
associated with transition to register ABI.
Repaired some broken comments.

Tested on link-register architectures (arm64, ppc64le)

Updates #40724.

Change-Id: Ie8433f6d38ec4a1d9705f22dcb596f267d81f203
Reviewed-on: https://go-review.googlesource.com/c/go/+/304189
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

1 files changed, 2 insertions, 13 deletions

diff --git a/src/cmd/compile/internal/abi/abiutils.go b/src/cmd/compile/internal/abi/abiutils.go
index 549c11306a..feda2153f7 100644
--- a/src/cmd/compile/internal/abi/abiutils.go
+++ b/src/cmd/compile/internal/abi/abiutils.go
@@ -225,27 +225,16 @@ func appendParamOffsets(offsets []int64, at int64, t *types.Type) ([]int64, int6
 	return offsets, at
 }
 
-// SpillOffset returns the offset *within the spill area* for the parameter that "a" describes.
-// Registers will be spilled here; if a memory home is needed (for a pointer method e.g.)
-// then that will be the address.
-// This will panic if "a" describes a stack-allocated parameter.
-func (a *ABIParamAssignment) SpillOffset() int32 {
-	if len(a.Registers) == 0 {
-		panic("Stack-allocated parameters have no spill offset")
-	}
-	return a.offset
-}
-
 // FrameOffset returns the frame-pointer-relative location that a function
 // would spill its input or output parameter to, if such a spill slot exists.
+// If there is none defined (e.g., register-allocated outputs) it panics.
 // 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 a.offset == -1 {
-		return -1
+		panic("Function parameter has no ABI-defined frame-pointer offset")
 	}
 	if len(a.Registers) == 0 { // passed on stack
 		return int64(a.offset) - i.config.LocalsOffset()