runtime: remove ret field from gobuf

It's not used for anything.

Change-Id: I031b3cdfe52b6b1cff4b3cb6713ffe588084542f
Reviewed-on: https://go-review.googlesource.com/c/go/+/652276
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/cmd/internal/obj/arm/obj5.go

@@ -551,7 +551,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 			p.From.Reg = q1.From.Reg
 			p.To.Type = obj.TYPE_MEM
 			p.To.Reg = REGTMP
-			p.To.Offset = 8 * 4 // offset of m.divmod
+			p.To.Offset = 7 * 4 // offset of m.divmod
 
 			/* MOV b, R8 */
 			p = obj.Appendp(p, newprog)

src/runtime/asm_386.s

@@ -291,10 +291,8 @@ TEXT gogo<>(SB), NOSPLIT, $0
 	get_tls(CX)
 	MOVL	DX, g(CX)
 	MOVL	gobuf_sp(BX), SP	// restore SP
-	MOVL	gobuf_ret(BX), AX
 	MOVL	gobuf_ctxt(BX), DX
 	MOVL	$0, gobuf_sp(BX)	// clear to help garbage collector
-	MOVL	$0, gobuf_ret(BX)
 	MOVL	$0, gobuf_ctxt(BX)
 	MOVL	gobuf_pc(BX), BX
 	JMP	BX
@@ -625,7 +623,6 @@ TEXT gosave_systemstack_switch<>(SB),NOSPLIT,$0
 	MOVL	AX, (g_sched+gobuf_sp)(BX)
 	MOVL	$runtime·systemstack_switch(SB), AX
 	MOVL	AX, (g_sched+gobuf_pc)(BX)
-	MOVL	$0, (g_sched+gobuf_ret)(BX)
 	// Assert ctxt is zero. See func save.
 	MOVL	(g_sched+gobuf_ctxt)(BX), AX
 	TESTL	AX, AX

src/runtime/asm_amd64.s

@@ -412,11 +412,9 @@ TEXT gogo<>(SB), NOSPLIT, $0
 	MOVQ	DX, g(CX)
 	MOVQ	DX, R14		// set the g register
 	MOVQ	gobuf_sp(BX), SP	// restore SP
-	MOVQ	gobuf_ret(BX), AX
 	MOVQ	gobuf_ctxt(BX), DX
 	MOVQ	gobuf_bp(BX), BP
 	MOVQ	$0, gobuf_sp(BX)	// clear to help garbage collector
-	MOVQ	$0, gobuf_ret(BX)
 	MOVQ	$0, gobuf_ctxt(BX)
 	MOVQ	$0, gobuf_bp(BX)
 	MOVQ	gobuf_pc(BX), BX
@@ -828,7 +826,6 @@ TEXT gosave_systemstack_switch<>(SB),NOSPLIT|NOFRAME,$0
 	MOVQ	R9, (g_sched+gobuf_pc)(R14)
 	LEAQ	8(SP), R9
 	MOVQ	R9, (g_sched+gobuf_sp)(R14)
-	MOVQ	$0, (g_sched+gobuf_ret)(R14)
 	MOVQ	BP, (g_sched+gobuf_bp)(R14)
 	// Assert ctxt is zero. See func save.
 	MOVQ	(g_sched+gobuf_ctxt)(R14), R9

src/runtime/asm_arm.s

@@ -226,11 +226,9 @@ TEXT gogo<>(SB),NOSPLIT|NOFRAME,$0
 	BL	setg<>(SB)
 	MOVW	gobuf_sp(R1), R13	// restore SP==R13
 	MOVW	gobuf_lr(R1), LR
-	MOVW	gobuf_ret(R1), R0
 	MOVW	gobuf_ctxt(R1), R7
 	MOVW	$0, R11
 	MOVW	R11, gobuf_sp(R1)	// clear to help garbage collector
-	MOVW	R11, gobuf_ret(R1)
 	MOVW	R11, gobuf_lr(R1)
 	MOVW	R11, gobuf_ctxt(R1)
 	MOVW	gobuf_pc(R1), R11
@@ -550,7 +548,6 @@ TEXT gosave_systemstack_switch<>(SB),NOSPLIT|NOFRAME,$0
 	MOVW	R13, (g_sched+gobuf_sp)(g)
 	MOVW	$0, R11
 	MOVW	R11, (g_sched+gobuf_lr)(g)
-	MOVW	R11, (g_sched+gobuf_ret)(g)
 	// Assert ctxt is zero. See func save.
 	MOVW	(g_sched+gobuf_ctxt)(g), R11
 	TST	R11, R11

src/runtime/asm_arm64.s

@@ -199,11 +199,9 @@ TEXT gogo<>(SB), NOSPLIT|NOFRAME, $0
 	MOVD	R0, RSP
 	MOVD	gobuf_bp(R5), R29
 	MOVD	gobuf_lr(R5), LR
-	MOVD	gobuf_ret(R5), R0
 	MOVD	gobuf_ctxt(R5), R26
 	MOVD	$0, gobuf_sp(R5)
 	MOVD	$0, gobuf_bp(R5)
-	MOVD	$0, gobuf_ret(R5)
 	MOVD	$0, gobuf_lr(R5)
 	MOVD	$0, gobuf_ctxt(R5)
 	CMP	ZR, ZR // set condition codes for == test, needed by stack split
@@ -985,7 +983,6 @@ TEXT gosave_systemstack_switch<>(SB),NOSPLIT|NOFRAME,$0
 	MOVD	R0, (g_sched+gobuf_sp)(g)
 	MOVD	R29, (g_sched+gobuf_bp)(g)
 	MOVD	$0, (g_sched+gobuf_lr)(g)
-	MOVD	$0, (g_sched+gobuf_ret)(g)
 	// Assert ctxt is zero. See func save.
 	MOVD	(g_sched+gobuf_ctxt)(g), R0
 	CBZ	R0, 2(PC)

src/runtime/asm_loong64.s

@@ -113,10 +113,8 @@ TEXT gogo<>(SB), NOSPLIT|NOFRAME, $0
 
 	MOVV	gobuf_sp(R4), R3
 	MOVV	gobuf_lr(R4), R1
-	MOVV	gobuf_ret(R4), R19
 	MOVV	gobuf_ctxt(R4), REGCTXT
 	MOVV	R0, gobuf_sp(R4)
-	MOVV	R0, gobuf_ret(R4)
 	MOVV	R0, gobuf_lr(R4)
 	MOVV	R0, gobuf_ctxt(R4)
 	MOVV	gobuf_pc(R4), R6
@@ -468,7 +466,6 @@ TEXT gosave_systemstack_switch<>(SB),NOSPLIT|NOFRAME,$0
 	MOVV	R19, (g_sched+gobuf_pc)(g)
 	MOVV	R3, (g_sched+gobuf_sp)(g)
 	MOVV	R0, (g_sched+gobuf_lr)(g)
-	MOVV	R0, (g_sched+gobuf_ret)(g)
 	// Assert ctxt is zero. See func save.
 	MOVV	(g_sched+gobuf_ctxt)(g), R19
 	BEQ	R19, 2(PC)

src/runtime/asm_mips64x.s

@@ -107,10 +107,8 @@ TEXT gogo<>(SB), NOSPLIT|NOFRAME, $0
 	MOVV	0(g), R2
 	MOVV	gobuf_sp(R3), R29
 	MOVV	gobuf_lr(R3), R31
-	MOVV	gobuf_ret(R3), R1
 	MOVV	gobuf_ctxt(R3), REGCTXT
 	MOVV	R0, gobuf_sp(R3)
-	MOVV	R0, gobuf_ret(R3)
 	MOVV	R0, gobuf_lr(R3)
 	MOVV	R0, gobuf_ctxt(R3)
 	MOVV	gobuf_pc(R3), R4
@@ -424,7 +422,6 @@ TEXT gosave_systemstack_switch<>(SB),NOSPLIT|NOFRAME,$0
 	MOVV	R1, (g_sched+gobuf_pc)(g)
 	MOVV	R29, (g_sched+gobuf_sp)(g)
 	MOVV	R0, (g_sched+gobuf_lr)(g)
-	MOVV	R0, (g_sched+gobuf_ret)(g)
 	// Assert ctxt is zero. See func save.
 	MOVV	(g_sched+gobuf_ctxt)(g), R1
 	BEQ	R1, 2(PC)

src/runtime/asm_mipsx.s

@@ -106,10 +106,8 @@ TEXT gogo<>(SB),NOSPLIT|NOFRAME,$0
 	JAL	runtime·save_g(SB)
 	MOVW	gobuf_sp(R3), R29
 	MOVW	gobuf_lr(R3), R31
-	MOVW	gobuf_ret(R3), R1
 	MOVW	gobuf_ctxt(R3), REGCTXT
 	MOVW	R0, gobuf_sp(R3)
-	MOVW	R0, gobuf_ret(R3)
 	MOVW	R0, gobuf_lr(R3)
 	MOVW	R0, gobuf_ctxt(R3)
 	MOVW	gobuf_pc(R3), R4
@@ -422,7 +420,6 @@ TEXT gosave_systemstack_switch<>(SB),NOSPLIT|NOFRAME,$0
 	MOVW	R1, (g_sched+gobuf_pc)(g)
 	MOVW	R29, (g_sched+gobuf_sp)(g)
 	MOVW	R0, (g_sched+gobuf_lr)(g)
-	MOVW	R0, (g_sched+gobuf_ret)(g)
 	// Assert ctxt is zero. See func save.
 	MOVW	(g_sched+gobuf_ctxt)(g), R1
 	BEQ	R1, 2(PC)

src/runtime/asm_ppc64x.s

@@ -154,10 +154,8 @@ TEXT gogo<>(SB), NOSPLIT|NOFRAME, $0
 	MOVD	24(R1), R2	// restore R2
 #endif
 	MOVD	R31, LR
-	MOVD	gobuf_ret(R5), R3
 	MOVD	gobuf_ctxt(R5), R11
 	MOVD	R0, gobuf_sp(R5)
-	MOVD	R0, gobuf_ret(R5)
 	MOVD	R0, gobuf_lr(R5)
 	MOVD	R0, gobuf_ctxt(R5)
 	CMP	R0, R0 // set condition codes for == test, needed by stack split
@@ -561,7 +559,6 @@ TEXT gosave_systemstack_switch<>(SB),NOSPLIT|NOFRAME,$0
 	MOVD	R31, (g_sched+gobuf_pc)(g)
 	MOVD	R1, (g_sched+gobuf_sp)(g)
 	MOVD	R0, (g_sched+gobuf_lr)(g)
-	MOVD	R0, (g_sched+gobuf_ret)(g)
 	// Assert ctxt is zero. See func save.
 	MOVD	(g_sched+gobuf_ctxt)(g), R31
 	CMP	R31, $0

src/runtime/asm_riscv64.s

@@ -262,10 +262,8 @@ TEXT gogo<>(SB), NOSPLIT|NOFRAME, $0
 
 	MOV	gobuf_sp(T0), X2
 	MOV	gobuf_lr(T0), RA
-	MOV	gobuf_ret(T0), A0
 	MOV	gobuf_ctxt(T0), CTXT
 	MOV	ZERO, gobuf_sp(T0)
-	MOV	ZERO, gobuf_ret(T0)
 	MOV	ZERO, gobuf_lr(T0)
 	MOV	ZERO, gobuf_ctxt(T0)
 	MOV	gobuf_pc(T0), T0
@@ -315,7 +313,6 @@ TEXT gosave_systemstack_switch<>(SB),NOSPLIT|NOFRAME,$0
 	MOV	X31, (g_sched+gobuf_pc)(g)
 	MOV	X2, (g_sched+gobuf_sp)(g)
 	MOV	ZERO, (g_sched+gobuf_lr)(g)
-	MOV	ZERO, (g_sched+gobuf_ret)(g)
 	// Assert ctxt is zero. See func save.
 	MOV	(g_sched+gobuf_ctxt)(g), X31
 	BEQ	ZERO, X31, 2(PC)

src/runtime/asm_s390x.s

@@ -193,10 +193,8 @@ TEXT gogo<>(SB), NOSPLIT|NOFRAME, $0
 	MOVD	0(g), R4
 	MOVD	gobuf_sp(R5), R15
 	MOVD	gobuf_lr(R5), LR
-	MOVD	gobuf_ret(R5), R3
 	MOVD	gobuf_ctxt(R5), R12
 	MOVD	$0, gobuf_sp(R5)
-	MOVD	$0, gobuf_ret(R5)
 	MOVD	$0, gobuf_lr(R5)
 	MOVD	$0, gobuf_ctxt(R5)
 	CMP	R0, R0 // set condition codes for == test, needed by stack split
@@ -522,7 +520,6 @@ TEXT gosave_systemstack_switch<>(SB),NOSPLIT|NOFRAME,$0
 	MOVD	R1, (g_sched+gobuf_pc)(g)
 	MOVD	R15, (g_sched+gobuf_sp)(g)
 	MOVD	$0, (g_sched+gobuf_lr)(g)
-	MOVD	$0, (g_sched+gobuf_ret)(g)
 	// Assert ctxt is zero. See func save.
 	MOVD	(g_sched+gobuf_ctxt)(g), R1
 	CMPBEQ	R1, $0, 2(PC)

src/runtime/asm_wasm.s

@@ -51,11 +51,9 @@ TEXT runtime·gogo(SB), NOSPLIT, $0-8
 	I64Load gobuf_pc(R0)
 	I64Store $0
 
-	MOVD gobuf_ret(R0), RET0
 	MOVD gobuf_ctxt(R0), CTXT
 	// clear to help garbage collector
 	MOVD $0, gobuf_sp(R0)
-	MOVD $0, gobuf_ret(R0)
 	MOVD $0, gobuf_ctxt(R0)
 
 	I32Const $1

src/runtime/proc.go

@@ -4399,7 +4399,6 @@ func save(pc, sp, bp uintptr) {
 	gp.sched.pc = pc
 	gp.sched.sp = sp
 	gp.sched.lr = 0
-	gp.sched.ret = 0
 	gp.sched.bp = bp
 	// We need to ensure ctxt is zero, but can't have a write
 	// barrier here. However, it should always already be zero.

src/runtime/runtime2.go

@@ -312,7 +312,6 @@ type gobuf struct {
 	pc   uintptr
 	g    guintptr
 	ctxt unsafe.Pointer
-	ret  uintptr
 	lr   uintptr
 	bp   uintptr // for framepointer-enabled architectures
 }
@@ -528,8 +527,7 @@ const (
 type m struct {
 	g0      *g     // goroutine with scheduling stack
 	morebuf gobuf  // gobuf arg to morestack
-	divmod  uint32 // div/mod denominator for arm - known to liblink
+	divmod  uint32 // div/mod denominator for arm - known to liblink (cmd/internal/obj/arm/obj5.go)
-	_       uint32 // align next field to 8 bytes
 
 	// Fields not known to debuggers.
 	procid          uint64            // for debuggers, but offset not hard-coded

src/runtime/sizeof_test.go

@@ -20,7 +20,7 @@ func TestSizeof(t *testing.T) {
 		_32bit uintptr // size on 32bit platforms
 		_64bit uintptr // size on 64bit platforms
 	}{
-		{runtime.G{}, 280, 440},   // g, but exported for testing
+		{runtime.G{}, 276, 432},   // g, but exported for testing
 		{runtime.Sudog{}, 56, 88}, // sudog, but exported for testing
 	}