feat(asm): encode the arm64 local-exec TLS load

Assisted-by: GLM 5.3 Flash

asm/arm64_reloc_test.go

@@ -124,3 +124,59 @@ func TestArm64GOObjRelocTypes(t *testing.T) {
 	// The detailed layout is covered by the goobj tests; here we only pin
 	// that emission succeeds with the new relocation kinds in play.
 }
+
+// TestArm64TLSLoad pins the local-exec TLS load: a symbol the file's own
+// GLOBL marks TLSBSS loads as one MOVZ word carrying the R_ARM64_TLS_LE
+// relocation (asm7.go case 69), the shape `go tool asm` emits for the
+// runtime's tls_g accesses.  A non-TLS GLOBL keeps the ADRP+LDR pair.
+func TestArm64TLSLoad(t *testing.T) {
+	img := parseArm64File(t, "#include \"textflag.h\"\n\n"+
+		"TEXT \u00b7f(SB), NOSPLIT, $0-0\n"+
+		"\tMOVD tlsvar(SB), R0\n"+
+		"\tMOVD plain(SB), R1\n"+
+		"\tRET\n"+
+		"GLOBL tlsvar(SB), TLSBSS, $8\n"+
+		"GLOBL plain(SB), NOPTR, $8\n")
+	fn := img.Funcs[0]
+	if fn.Size != 4+8+4 {
+		t.Fatalf("function size = %d, want 16", fn.Size)
+	}
+	if w := binary.LittleEndian.Uint32(img.Code[fn.Offset:]); w != 0xd2800000 {
+		t.Errorf("TLS load word = %08x, want MOVZ 0 (d2800000)", w)
+	}
+	var tlsSeen, plainSeen bool
+	for _, r := range fn.Relocs {
+		if r.Name != "tlsvar" {
+			continue
+		}
+		tlsSeen = true
+		if r.Kind != RelArm64TLSLE {
+			t.Errorf("tlsvar reloc kind = %v, want RelArm64TLSLE", r.Kind)
+		}
+		if r.Off != 0 {
+			t.Errorf("tlsvar reloc off = %d, want 0", r.Off)
+		}
+	}
+	for _, r := range fn.Relocs {
+		if r.Name == "plain" && r.Kind == RelArm64LDST64 {
+			plainSeen = true
+		}
+	}
+	if !tlsSeen {
+		t.Error("no tlsvar relocation recorded")
+	}
+	if !plainSeen {
+		t.Error("the plain GLOBL load lost its ADRP+LDR relocation")
+	}
+	// The other widths have no TLS row: the toolchain refuses them.
+	f, errs := parser.Parse("k_arm64.s", "TEXT \u00b7f(SB), NOSPLIT, $0-0\n"+
+		"\tMOVW tlsvar(SB), R0\n"+
+		"\tRET\n"+
+		"GLOBL tlsvar(SB), TLSBSS, $8\n")
+	if len(errs) > 0 {
+		t.Fatalf("parse: %v", errs)
+	}
+	if _, err := AssembleFileARM64(f); err == nil {
+		t.Error("MOVW of a TLS symbol assembled, want an illegal combination")
+	}
+}