diff options
| author | Keith Randall <khr@golang.org> | 2023-05-02 17:37:00 +0000 |
|---|---|---|
| committer | Keith Randall <khr@google.com> | 2023-05-19 18:10:11 +0000 |
| commit | bd3f44e4ffe54e9cf841ebc8356e403bb38436bd (patch) | |
| tree | fa91f127398bdf3fd9058b37bd7a228f4ad2ae96 /src/cmd/link/internal/ld | |
| parent | b60db8f7d92fb2c87b6f416ebb38a6924978aa8c (diff) | |
| download | go-bd3f44e4ffe54e9cf841ebc8356e403bb38436bd.tar.xz | |
cmd/compile: constant-fold loads from constant dictionaries and types
Retrying the original CL with a small modification. The original CL
did not handle the case of reading an itab out of a dictionary
correctly. When we read an itab out of a dictionary, we must treat
the type inside that itab as maybe being put in an interface.
Original CL: 486895
Revert CL: 490156
Change-Id: Id2dc1699d184cd8c63dac83986a70b60b4e6cbd7
Reviewed-on: https://go-review.googlesource.com/c/go/+/491495
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Diffstat (limited to 'src/cmd/link/internal/ld')
| -rw-r--r-- | src/cmd/link/internal/ld/deadcode.go | 8 | ||||
| -rw-r--r-- | src/cmd/link/internal/ld/decodesym.go | 6 |
2 files changed, 14 insertions, 0 deletions
diff --git a/src/cmd/link/internal/ld/deadcode.go b/src/cmd/link/internal/ld/deadcode.go index c0969b25b0..c687565878 100644 --- a/src/cmd/link/internal/ld/deadcode.go +++ b/src/cmd/link/internal/ld/deadcode.go @@ -180,6 +180,14 @@ func (d *deadcodePass) flood() { // converted to an interface, i.e. should have UsedInIface set. See the // comment below for why we need to unset the Reachable bit and re-mark it. rs := r.Sym() + if d.ldr.IsItab(rs) { + // This relocation can also point at an itab, in which case it + // means "the _type field of that itab". + rs = decodeItabType(d.ldr, d.ctxt.Arch, rs) + } + if !d.ldr.IsGoType(rs) && !d.ctxt.linkShared { + panic(fmt.Sprintf("R_USEIFACE in %s references %s which is not a type or itab", d.ldr.SymName(symIdx), d.ldr.SymName(rs))) + } if !d.ldr.AttrUsedInIface(rs) { d.ldr.SetAttrUsedInIface(rs, true) if d.ldr.AttrReachable(rs) { diff --git a/src/cmd/link/internal/ld/decodesym.go b/src/cmd/link/internal/ld/decodesym.go index c01d6c1163..05da11ec1e 100644 --- a/src/cmd/link/internal/ld/decodesym.go +++ b/src/cmd/link/internal/ld/decodesym.go @@ -300,3 +300,9 @@ func findShlibSection(ctxt *Link, path string, addr uint64) *elf.Section { func decodetypeGcprogShlib(ctxt *Link, data []byte) uint64 { return decodeInuxi(ctxt.Arch, data[2*int32(ctxt.Arch.PtrSize)+8+1*int32(ctxt.Arch.PtrSize):], ctxt.Arch.PtrSize) } + +// decodeItabType returns the itab._type field from an itab. +func decodeItabType(ldr *loader.Loader, arch *sys.Arch, symIdx loader.Sym) loader.Sym { + relocs := ldr.Relocs(symIdx) + return decodeRelocSym(ldr, symIdx, &relocs, int32(arch.PtrSize)) +} |