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cmd/internal/obj, cmd/link: record ABIs and aliases in Go obj files

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This repurposes the "version" field of a symbol reference in the Go
object file format to be an ABI field. Currently, this is just 0 or 1
depending on whether the symbol is static (the linker turns it into a
different internal version number), so it's already only tenuously a
symbol version. We change this to be -1 for static symbols and
otherwise by the ABI number.

This also adds a separate list of ABI alias symbols to be recorded in
the object file. The ABI aliases must be a separate list and not just
part of the symbol definitions because it's possible to have a symbol
defined in one package and the alias "defined" in a different package.
For example, this can happen if a symbol is defined in assembly in one
package and stubbed in a different package. The stub triggers the
generation of the ABI alias, but in a different package from the
definition.

For #27539.

Change-Id: I015c9fe54690c027de6ef77e22b5585976a01587
Reviewed-on: https://go-review.googlesource.com/c/147157
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
This commit is contained in:
Austin Clements 2018-10-26 13:53:02 -04:00
parent 07544c7e80
commit c5718b6b26
6 changed files with 96 additions and 26 deletions
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15
src/cmd/link/internal/sym/symbol.go
View file

@ -5,6 +5,7 @@
package sym
import (
"cmd/internal/obj"
"cmd/internal/objabi"
"cmd/internal/sys"
"debug/elf"
@ -52,9 +53,21 @@ type AuxSymbol struct {
}
const (
SymVerStatic = 10 // Minimum version used by static (file-local) syms
SymVerABI0 = 0
SymVerABIInternal = 1
SymVerStatic = 10 // Minimum version used by static (file-local) syms
)
func ABIToVersion(abi obj.ABI) int {
switch abi {
case obj.ABI0:
return SymVerABI0
case obj.ABIInternal:
return SymVerABIInternal
}
return -1
}
func (s *Symbol) String() string {
if s.Version == 0 {
return s.Name