feat(asm): the TLS access pair in the toolchain's one-instruction form

Assisted-by: GLM 5.3 Flash

CHANGELOG.md

@@ -15,13 +15,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   branch optimiser does; symbol immediates (`MOVQ $sym(SB), AX`)
   assemble to the toolchain's RIP-relative LEA with an R_PCREL
   relocation; negated constant expressions in operands (`ADJSP
-  $-(REGS - 8)`, the shape the cgo ABI macros write) fold; and `gasm
-  asm` predefines the `GOARCH_<arch>` and `GOOS_<goos>` macros the go
-  command passes to `go tool asm`, so GOROOT headers' `#ifdef
-  GOARCH_amd64` platform blocks (`go_tls.h`'s `get_tls` and friends)
-  select as intended.  The GOROOT corpus measure moves to 261 of 353
-  files assembling for every target architecture (73.9 %), 87.5 % of
-  the real-code corpus, from 70.8 % and 82.2 %.
+  $-(REGS - 8)`, the shape the cgo ABI macros write) fold; the TLS
+  access pair assembles as the toolchain's one-instruction form (the
+  bare `MOVQ TLS, r` load nops out and `off(r)(TLS*1)` folds to the
+  segment-prefixed absolute whose disp32 carries the R_TLSLE
+  relocation, per-GOOS); and `gasm asm` predefines the `GOARCH_<arch>`
+  and `GOOS_<goos>` macros the go command passes to `go tool asm`, so
+  GOROOT headers' `#ifdef GOARCH_amd64` platform blocks (`go_tls.h`'s
+  `get_tls` and friends) select as intended.  The GOROOT corpus measure
+  moves to 267 of 353 files assembling for every target architecture
+  (75.6 %), 89.4 % of the real-code corpus, from 70.8 % and 82.2 %.
 
 ### Added