all: delete riscv64 non-register ABI fallback path

Change-Id: I9e997b59ffb868575b780b9660df1f5ac322b79a
Reviewed-on: https://go-review.googlesource.com/c/go/+/443556
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Wayne Zuo <wdvxdr@golangcn.org>
Reviewed-by: David Chase <drchase@google.com>

3 files changed, 5 insertions, 106 deletions

diff --git a/src/runtime/asm_riscv64.s b/src/runtime/asm_riscv64.s
index 389851beb9..31b81aea12 100644
--- a/src/runtime/asm_riscv64.s
+++ b/src/runtime/asm_riscv64.s
@@ -268,11 +268,7 @@ TEXT runtime·procyield(SB),NOSPLIT,$0-0
 
 // func mcall(fn func(*g))
 TEXT runtime·mcall<ABIInternal>(SB), NOSPLIT|NOFRAME, $0-8
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	X10, CTXT
-#else
-	MOV	fn+0(FP), CTXT
-#endif
 
 	// Save caller state in g->sched
 	MOV	X2, (g_sched+gobuf_sp)(g)
@@ -644,7 +640,6 @@ TEXT ·checkASM(SB),NOSPLIT,$0-1
 	MOV	T0, ret+0(FP)
 	RET
 
-#ifdef GOEXPERIMENT_regabiargs
 // spillArgs stores return values from registers to a *internal/abi.RegArgs in X25.
 TEXT ·spillArgs(SB),NOSPLIT,$0-0
 	MOV	X10, (0*8)(X25)
@@ -716,13 +711,6 @@ TEXT ·unspillArgs(SB),NOSPLIT,$0-0
 	MOVD	(30*8)(X25), F22
 	MOVD	(31*8)(X25), F23
 	RET
-#else
-TEXT ·spillArgs(SB),NOSPLIT,$0-0
-	RET
-
-TEXT ·unspillArgs(SB),NOSPLIT,$0-0
-	RET
-#endif
 
 // gcWriteBarrier performs a heap pointer write and informs the GC.
 //
@@ -832,157 +820,72 @@ flush:
 // corresponding runtime handler.
 // The tail call makes these stubs disappear in backtraces.
 TEXT runtime·panicIndex<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T0, X10
 	MOV	T1, X11
-#else
-	MOV	T0, x+0(FP)
-	MOV	T1, y+8(FP)
-#endif
 	JMP	runtime·goPanicIndex<ABIInternal>(SB)
 TEXT runtime·panicIndexU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T0, X10
 	MOV	T1, X11
-#else
-	MOV	T0, x+0(FP)
-	MOV	T1, y+8(FP)
-#endif
 	JMP	runtime·goPanicIndexU<ABIInternal>(SB)
 TEXT runtime·panicSliceAlen<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T1, X10
 	MOV	T2, X11
-#else
-	MOV	T1, x+0(FP)
-	MOV	T2, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAlen<ABIInternal>(SB)
 TEXT runtime·panicSliceAlenU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T1, X10
 	MOV	T2, X11
-#else
-	MOV	T1, x+0(FP)
-	MOV	T2, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAlenU<ABIInternal>(SB)
 TEXT runtime·panicSliceAcap<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T1, X10
 	MOV	T2, X11
-#else
-	MOV	T1, x+0(FP)
-	MOV	T2, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAcap<ABIInternal>(SB)
 TEXT runtime·panicSliceAcapU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T1, X10
 	MOV	T2, X11
-#else
-	MOV	T1, x+0(FP)
-	MOV	T2, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAcapU<ABIInternal>(SB)
 TEXT runtime·panicSliceB<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T0, X10
 	MOV	T1, X11
-#else
-	MOV	T0, x+0(FP)
-	MOV	T1, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceB<ABIInternal>(SB)
 TEXT runtime·panicSliceBU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T0, X10
 	MOV	T1, X11
-#else
-	MOV	T0, x+0(FP)
-	MOV	T1, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceBU<ABIInternal>(SB)
 TEXT runtime·panicSlice3Alen<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T2, X10
 	MOV	T3, X11
-#else
-	MOV	T2, x+0(FP)
-	MOV	T3, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3Alen<ABIInternal>(SB)
 TEXT runtime·panicSlice3AlenU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T2, X10
 	MOV	T3, X11
-#else
-	MOV	T2, x+0(FP)
-	MOV	T3, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3AlenU<ABIInternal>(SB)
 TEXT runtime·panicSlice3Acap<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T2, X10
 	MOV	T3, X11
-#else
-	MOV	T2, x+0(FP)
-	MOV	T3, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3Acap<ABIInternal>(SB)
 TEXT runtime·panicSlice3AcapU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T2, X10
 	MOV	T3, X11
-#else
-	MOV	T2, x+0(FP)
-	MOV	T3, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3AcapU<ABIInternal>(SB)
 TEXT runtime·panicSlice3B<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T1, X10
 	MOV	T2, X11
-#else
-	MOV	T1, x+0(FP)
-	MOV	T2, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3B<ABIInternal>(SB)
 TEXT runtime·panicSlice3BU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T1, X10
 	MOV	T2, X11
-#else
-	MOV	T1, x+0(FP)
-	MOV	T2, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3BU<ABIInternal>(SB)
 TEXT runtime·panicSlice3C<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T0, X10
 	MOV	T1, X11
-#else
-	MOV	T0, x+0(FP)
-	MOV	T1, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3C<ABIInternal>(SB)
 TEXT runtime·panicSlice3CU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T0, X10
 	MOV	T1, X11
-#else
-	MOV	T0, x+0(FP)
-	MOV	T1, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3CU<ABIInternal>(SB)
 TEXT runtime·panicSliceConvert<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOV	T2, X10
 	MOV	T3, X11
-#else
-	MOV	T2, x+0(FP)
-	MOV	T3, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceConvert<ABIInternal>(SB)
 
 DATA	runtime·mainPC+0(SB)/8,$runtime·main<ABIInternal>(SB)
diff --git a/src/runtime/memclr_riscv64.s b/src/runtime/memclr_riscv64.s
index 4cf0f5488f..d12b545b1e 100644
--- a/src/runtime/memclr_riscv64.s
+++ b/src/runtime/memclr_riscv64.s
@@ -8,10 +8,8 @@
 
 // void runtime·memclrNoHeapPointers(void*, uintptr)
 TEXT runtime·memclrNoHeapPointers<ABIInternal>(SB),NOSPLIT,$0-16
-#ifndef GOEXPERIMENT_regabiargs
-	MOV	ptr+0(FP), X10
-	MOV	n+8(FP), X11
-#endif
+	// X10 = ptr
+	// X11 = n
 
 	// If less than 8 bytes, do single byte zeroing.
 	MOV	$8, X9
diff --git a/src/runtime/memmove_riscv64.s b/src/runtime/memmove_riscv64.s
index 538aee3642..79d90c1adb 100644
--- a/src/runtime/memmove_riscv64.s
+++ b/src/runtime/memmove_riscv64.s
@@ -8,11 +8,9 @@
 
 // void runtime·memmove(void*, void*, uintptr)
 TEXT runtime·memmove<ABIInternal>(SB),NOSPLIT,$-0-24
-#ifndef GOEXPERIMENT_regabiargs
-	MOV	to+0(FP), A0
-	MOV	from+8(FP), A1
-	MOV	n+16(FP), A2
-#endif
+	// A0 = to
+	// A1 = from
+	// A2 = n
 	ADD	A1, A2, T5
 
 	// If the destination is ahead of the source, start at the end of the