[dev.typeparams] runtime, internal/bytealg: remove regabi fallback code on AMD64

As we commit to always enabling register ABI on AMD64, remove the
fallback code.

Change-Id: I30556858ba4bac367495fa94f6a8682ecd771196
Reviewed-on: https://go-review.googlesource.com/c/go/+/341152
Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Austin Clements <austin@google.com>

6 files changed, 0 insertions, 309 deletions

diff --git a/src/internal/bytealg/compare_amd64.s b/src/internal/bytealg/compare_amd64.s
index 8295acb03a..4ccaca5e87 100644
--- a/src/internal/bytealg/compare_amd64.s
+++ b/src/internal/bytealg/compare_amd64.s
@@ -6,7 +6,6 @@
 #include "textflag.h"
 
 TEXT ·Compare<ABIInternal>(SB),NOSPLIT,$0-56
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = a_base (want in SI)
 	// BX = a_len  (want in BX)
 	// CX = a_cap  (unused)
@@ -15,17 +14,9 @@ TEXT ·Compare<ABIInternal>(SB),NOSPLIT,$0-56
 	// R8 = b_cap  (unused)
 	MOVQ	SI, DX
 	MOVQ	AX, SI
-#else
-	MOVQ	a_base+0(FP), SI
-	MOVQ	a_len+8(FP), BX
-	MOVQ	b_base+24(FP), DI
-	MOVQ	b_len+32(FP), DX
-	LEAQ	ret+48(FP), R9
-#endif
 	JMP	cmpbody<>(SB)
 
 TEXT runtime·cmpstring<ABIInternal>(SB),NOSPLIT,$0-40
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = a_base (want in SI)
 	// BX = a_len  (want in BX)
 	// CX = b_base (want in DI)
@@ -33,13 +24,6 @@ TEXT runtime·cmpstring<ABIInternal>(SB),NOSPLIT,$0-40
 	MOVQ	AX, SI
 	MOVQ	DI, DX
 	MOVQ	CX, DI
-#else
-	MOVQ	a_base+0(FP), SI
-	MOVQ	a_len+8(FP), BX
-	MOVQ	b_base+16(FP), DI
-	MOVQ	b_len+24(FP), DX
-	LEAQ	ret+32(FP), R9
-#endif
 	JMP	cmpbody<>(SB)
 
 // input:
@@ -47,12 +31,8 @@ TEXT runtime·cmpstring<ABIInternal>(SB),NOSPLIT,$0-40
 //   DI = b
 //   BX = alen
 //   DX = blen
-#ifndef GOEXPERIMENT_regabiargs
-//   R9 = address of output word (stores -1/0/1 here)
-#else
 // output:
 //   AX = output (-1/0/1)
-#endif
 TEXT cmpbody<>(SB),NOSPLIT,$0-0
 	CMPQ	SI, DI
 	JEQ	allsame
@@ -100,9 +80,6 @@ diff16:
 	CMPB	CX, (DI)(BX*1)
 	SETHI	AX
 	LEAQ	-1(AX*2), AX	// convert 1/0 to +1/-1
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	AX, (R9)
-#endif
 	RET
 
 	// 0 through 16 bytes left, alen>=8, blen>=8
@@ -128,9 +105,6 @@ diff8:
 	SHRQ	CX, AX	// move a's bit to bottom
 	ANDQ	$1, AX	// mask bit
 	LEAQ	-1(AX*2), AX // 1/0 => +1/-1
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	AX, (R9)
-#endif
 	RET
 
 	// 0-7 bytes in common
@@ -169,9 +143,6 @@ di_finish:
 	SHRQ	CX, SI	// move a's bit to bottom
 	ANDQ	$1, SI	// mask bit
 	LEAQ	-1(SI*2), AX // 1/0 => +1/-1
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	AX, (R9)
-#endif
 	RET
 
 allsame:
@@ -181,9 +152,6 @@ allsame:
 	SETGT	AX	// 1 if alen > blen
 	SETEQ	CX	// 1 if alen == blen
 	LEAQ	-1(CX)(AX*2), AX	// 1,0,-1 result
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	AX, (R9)
-#endif
 	RET
 
 	// this works for >= 64 bytes of data.
diff --git a/src/internal/bytealg/equal_amd64.s b/src/internal/bytealg/equal_amd64.s
index 6f12d2a169..dd46e2e0fd 100644
--- a/src/internal/bytealg/equal_amd64.s
+++ b/src/internal/bytealg/equal_amd64.s
@@ -7,7 +7,6 @@
 
 // memequal(a, b unsafe.Pointer, size uintptr) bool
 TEXT runtime·memequal<ABIInternal>(SB),NOSPLIT,$0-25
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = a    (want in SI)
 	// BX = b    (want in DI)
 	// CX = size (want in BX)
@@ -20,22 +19,9 @@ neq:
 	MOVQ	BX, DI
 	MOVQ	CX, BX
 	JMP	memeqbody<>(SB)
-#else
-	MOVQ	a+0(FP), SI
-	MOVQ	b+8(FP), DI
-	CMPQ	SI, DI
-	JEQ	eq
-	MOVQ	size+16(FP), BX
-	LEAQ	ret+24(FP), AX
-	JMP	memeqbody<>(SB)
-eq:
-	MOVB	$1, ret+24(FP)
-	RET
-#endif
 
 // memequal_varlen(a, b unsafe.Pointer) bool
 TEXT runtime·memequal_varlen<ABIInternal>(SB),NOSPLIT,$0-17
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = a       (want in SI)
 	// BX = b       (want in DI)
 	// 8(DX) = size (want in BX)
@@ -48,29 +34,13 @@ neq:
 	MOVQ	BX, DI
 	MOVQ	8(DX), BX    // compiler stores size at offset 8 in the closure
 	JMP	memeqbody<>(SB)
-#else
-	MOVQ	a+0(FP), SI
-	MOVQ	b+8(FP), DI
-	CMPQ	SI, DI
-	JEQ	eq
-	MOVQ	8(DX), BX    // compiler stores size at offset 8 in the closure
-	LEAQ	ret+16(FP), AX
-	JMP	memeqbody<>(SB)
-eq:
-	MOVB	$1, ret+16(FP)
-	RET
-#endif
 
 // Input:
 //   a in SI
 //   b in DI
 //   count in BX
-#ifndef GOEXPERIMENT_regabiargs
-//   address of result byte in AX
-#else
 // Output:
 //   result in AX
-#endif
 TEXT memeqbody<>(SB),NOSPLIT,$0-0
 	CMPQ	BX, $8
 	JB	small
@@ -104,11 +74,7 @@ hugeloop:
 	SUBQ	$64, BX
 	CMPL	DX, $0xffff
 	JEQ	hugeloop
-#ifdef GOEXPERIMENT_regabiargs
 	XORQ	AX, AX	// return 0
-#else
-	MOVB	$0, (AX)
-#endif
 	RET
 
 	// 64 bytes at a time using ymm registers
@@ -129,11 +95,7 @@ hugeloop_avx2:
 	CMPL	DX, $0xffffffff
 	JEQ	hugeloop_avx2
 	VZEROUPPER
-#ifdef GOEXPERIMENT_regabiargs
 	XORQ	AX, AX	// return 0
-#else
-	MOVB	$0, (AX)
-#endif
 	RET
 
 bigloop_avx2:
@@ -150,11 +112,7 @@ bigloop:
 	SUBQ	$8, BX
 	CMPQ	CX, DX
 	JEQ	bigloop
-#ifdef GOEXPERIMENT_regabiargs
 	XORQ	AX, AX	// return 0
-#else
-	MOVB	$0, (AX)
-#endif
 	RET
 
 	// remaining 0-8 bytes
@@ -162,11 +120,7 @@ leftover:
 	MOVQ	-8(SI)(BX*1), CX
 	MOVQ	-8(DI)(BX*1), DX
 	CMPQ	CX, DX
-#ifdef GOEXPERIMENT_regabiargs
 	SETEQ	AX
-#else
-	SETEQ	(AX)
-#endif
 	RET
 
 small:
@@ -201,10 +155,5 @@ di_finish:
 	SUBQ	SI, DI
 	SHLQ	CX, DI
 equal:
-#ifdef GOEXPERIMENT_regabiargs
 	SETEQ	AX
-#else
-	SETEQ	(AX)
-#endif
 	RET
-
diff --git a/src/runtime/asm_amd64.s b/src/runtime/asm_amd64.s
index 2d8f4c2412..2083ecb53e 100644
--- a/src/runtime/asm_amd64.s
+++ b/src/runtime/asm_amd64.s
@@ -277,7 +277,6 @@ TEXT gogo<>(SB), NOSPLIT, $0
 // Switch to m->g0's stack, call fn(g).
 // Fn must never return. It should gogo(&g->sched)
 // to keep running g.
-#ifdef GOEXPERIMENT_regabiargs
 TEXT runtime·mcall<ABIInternal>(SB), NOSPLIT, $0-8
 	MOVQ	AX, DX	// DX = fn
 
@@ -306,38 +305,6 @@ goodm:
 	POPQ	AX
 	JMP	runtime·badmcall2(SB)
 	RET
-#else
-TEXT runtime·mcall(SB), NOSPLIT, $0-8
-	MOVQ	fn+0(FP), DI
-
-	get_tls(CX)
-	MOVQ	g(CX), AX	// save state in g->sched
-	MOVQ	0(SP), BX	// caller's PC
-	MOVQ	BX, (g_sched+gobuf_pc)(AX)
-	LEAQ	fn+0(FP), BX	// caller's SP
-	MOVQ	BX, (g_sched+gobuf_sp)(AX)
-	MOVQ	BP, (g_sched+gobuf_bp)(AX)
-
-	// switch to m->g0 & its stack, call fn
-	MOVQ	g(CX), BX
-	MOVQ	g_m(BX), BX
-	MOVQ	m_g0(BX), SI
-	CMPQ	SI, AX	// if g == m->g0 call badmcall
-	JNE	3(PC)
-	MOVQ	$runtime·badmcall(SB), AX
-	JMP	AX
-	MOVQ	SI, g(CX)	// g = m->g0
-	MOVQ	SI, R14	// set the g register
-	MOVQ	(g_sched+gobuf_sp)(SI), SP	// sp = m->g0->sched.sp
-	PUSHQ	AX
-	MOVQ	DI, DX
-	MOVQ	0(DI), DI
-	CALL	DI
-	POPQ	AX
-	MOVQ	$runtime·badmcall2(SB), AX
-	JMP	AX
-	RET
-#endif
 
 // systemstack_switch is a dummy routine that systemstack leaves at the bottom
 // of the G stack. We need to distinguish the routine that
@@ -465,7 +432,6 @@ TEXT runtime·morestack_noctxt(SB),NOSPLIT,$0
 	MOVL	$0, DX
 	JMP	runtime·morestack(SB)
 
-#ifdef GOEXPERIMENT_regabireflect
 // spillArgs stores return values from registers to a *internal/abi.RegArgs in R12.
 TEXT ·spillArgs(SB),NOSPLIT,$0-0
 	MOVQ AX, 0(R12)
@@ -521,15 +487,6 @@ TEXT ·unspillArgs(SB),NOSPLIT,$0-0
 	MOVQ 176(R12), X13
 	MOVQ 184(R12), X14
 	RET
-#else
-// spillArgs stores return values from registers to a pointer in R12.
-TEXT ·spillArgs(SB),NOSPLIT,$0-0
-	RET
-
-// unspillArgs loads args into registers from a pointer in R12.
-TEXT ·unspillArgs(SB),NOSPLIT,$0-0
-	RET
-#endif
 
 // reflectcall: call a function with the given argument list
 // func call(stackArgsType *_type, f *FuncVal, stackArgs *byte, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs).
@@ -988,61 +945,34 @@ done:
 // func memhash(p unsafe.Pointer, h, s uintptr) uintptr
 // hash function using AES hardware instructions
 TEXT runtime·memhash<ABIInternal>(SB),NOSPLIT,$0-32
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = ptr to data
 	// BX = seed
 	// CX = size
-#endif
 	CMPB	runtime·useAeshash(SB), $0
 	JEQ	noaes
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	p+0(FP), AX	// ptr to data
-	MOVQ	s+16(FP), CX	// size
-	LEAQ	ret+24(FP), DX
-#endif
 	JMP	aeshashbody<>(SB)
 noaes:
 	JMP	runtime·memhashFallback<ABIInternal>(SB)
 
 // func strhash(p unsafe.Pointer, h uintptr) uintptr
 TEXT runtime·strhash<ABIInternal>(SB),NOSPLIT,$0-24
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = ptr to string struct
 	// BX = seed
-#endif
 	CMPB	runtime·useAeshash(SB), $0
 	JEQ	noaes
-#ifndef GOEXPERIMENT_regabiargs
-	MOVQ	p+0(FP), AX	// ptr to string struct
-#endif
 	MOVQ	8(AX), CX	// length of string
 	MOVQ	(AX), AX	// string data
-#ifndef GOEXPERIMENT_regabiargs
-	LEAQ	ret+16(FP), DX
-#endif
 	JMP	aeshashbody<>(SB)
 noaes:
 	JMP	runtime·strhashFallback<ABIInternal>(SB)
 
 // AX: data
-#ifdef GOEXPERIMENT_regabiargs
 // BX: hash seed
-#else
-// h+8(FP): hash seed
-#endif
 // CX: length
-#ifdef GOEXPERIMENT_regabiargs
 // At return: AX = return value
-#else
-// DX: address to put return value
-#endif
 TEXT aeshashbody<>(SB),NOSPLIT,$0-0
 	// Fill an SSE register with our seeds.
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	BX, X0				// 64 bits of per-table hash seed
-#else
-	MOVQ	h+8(FP), X0			// 64 bits of per-table hash seed
-#endif
 	PINSRW	$4, CX, X0			// 16 bits of length
 	PSHUFHW $0, X0, X0			// repeat length 4 times total
 	MOVO	X0, X1				// save unscrambled seed
@@ -1079,11 +1009,7 @@ final1:
 	AESENC	X1, X1	// scramble combo 3 times
 	AESENC	X1, X1
 	AESENC	X1, X1
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X1, AX	// return X1
-#else
-	MOVQ	X1, (DX)
-#endif
 	RET
 
 endofpage:
@@ -1099,11 +1025,7 @@ endofpage:
 aes0:
 	// Return scrambled input seed
 	AESENC	X0, X0
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X0, AX	// return X0
-#else
-	MOVQ	X0, (DX)
-#endif
 	RET
 
 aes16:
@@ -1133,11 +1055,7 @@ aes17to32:
 
 	// combine results
 	PXOR	X3, X2
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X2, AX	// return X2
-#else
-	MOVQ	X2, (DX)
-#endif
 	RET
 
 aes33to64:
@@ -1179,11 +1097,7 @@ aes33to64:
 	PXOR	X6, X4
 	PXOR	X7, X5
 	PXOR	X5, X4
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X4, AX	// return X4
-#else
-	MOVQ	X4, (DX)
-#endif
 	RET
 
 aes65to128:
@@ -1267,11 +1181,7 @@ aes65to128:
 	PXOR	X9, X8
 	// X15 must be zero on return
 	PXOR	X15, X15
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X8, AX	// return X8
-#else
-	MOVQ	X8, (DX)
-#endif
 	RET
 
 aes129plus:
@@ -1389,37 +1299,22 @@ aesloop:
 	PXOR	X9, X8
 	// X15 must be zero on return
 	PXOR	X15, X15
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X8, AX	// return X8
-#else
-	MOVQ	X8, (DX)
-#endif
 	RET
 
 // func memhash32(p unsafe.Pointer, h uintptr) uintptr
 // ABIInternal for performance.
 TEXT runtime·memhash32<ABIInternal>(SB),NOSPLIT,$0-24
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = ptr to data
 	// BX = seed
-#endif
 	CMPB	runtime·useAeshash(SB), $0
 	JEQ	noaes
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	BX, X0	// X0 = seed
-#else
-	MOVQ	p+0(FP), AX	// ptr to data
-	MOVQ	h+8(FP), X0	// seed
-#endif
 	PINSRD	$2, (AX), X0	// data
 	AESENC	runtime·aeskeysched+0(SB), X0
 	AESENC	runtime·aeskeysched+16(SB), X0
 	AESENC	runtime·aeskeysched+32(SB), X0
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X0, AX	// return X0
-#else
-	MOVQ	X0, ret+16(FP)
-#endif
 	RET
 noaes:
 	JMP	runtime·memhash32Fallback<ABIInternal>(SB)
@@ -1427,28 +1322,16 @@ noaes:
 // func memhash64(p unsafe.Pointer, h uintptr) uintptr
 // ABIInternal for performance.
 TEXT runtime·memhash64<ABIInternal>(SB),NOSPLIT,$0-24
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = ptr to data
 	// BX = seed
-#else
-#endif
 	CMPB	runtime·useAeshash(SB), $0
 	JEQ	noaes
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	BX, X0	// X0 = seed
-#else
-	MOVQ	p+0(FP), AX	// ptr to data
-	MOVQ	h+8(FP), X0	// seed
-#endif
 	PINSRQ	$1, (AX), X0	// data
 	AESENC	runtime·aeskeysched+0(SB), X0
 	AESENC	runtime·aeskeysched+16(SB), X0
 	AESENC	runtime·aeskeysched+32(SB), X0
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X0, AX	// return X0
-#else
-	MOVQ	X0, ret+16(FP)
-#endif
 	RET
 noaes:
 	JMP	runtime·memhash64Fallback<ABIInternal>(SB)
@@ -1925,146 +1808,61 @@ TEXT runtime·debugCallPanicked(SB),NOSPLIT,$16-16
 // The tail call makes these stubs disappear in backtraces.
 // Defined as ABIInternal since they do not use the stack-based Go ABI.
 TEXT runtime·panicIndex<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicIndex<ABIInternal>(SB)
 TEXT runtime·panicIndexU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicIndexU<ABIInternal>(SB)
 TEXT runtime·panicSliceAlen<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAlen<ABIInternal>(SB)
 TEXT runtime·panicSliceAlenU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAlenU<ABIInternal>(SB)
 TEXT runtime·panicSliceAcap<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAcap<ABIInternal>(SB)
 TEXT runtime·panicSliceAcapU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceAcapU<ABIInternal>(SB)
 TEXT runtime·panicSliceB<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceB<ABIInternal>(SB)
 TEXT runtime·panicSliceBU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceBU<ABIInternal>(SB)
 TEXT runtime·panicSlice3Alen<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	DX, AX
-#else
-	MOVQ	DX, x+0(FP)
-	MOVQ	BX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3Alen<ABIInternal>(SB)
 TEXT runtime·panicSlice3AlenU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	DX, AX
-#else
-	MOVQ	DX, x+0(FP)
-	MOVQ	BX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3AlenU<ABIInternal>(SB)
 TEXT runtime·panicSlice3Acap<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	DX, AX
-#else
-	MOVQ	DX, x+0(FP)
-	MOVQ	BX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3Acap<ABIInternal>(SB)
 TEXT runtime·panicSlice3AcapU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	DX, AX
-#else
-	MOVQ	DX, x+0(FP)
-	MOVQ	BX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3AcapU<ABIInternal>(SB)
 TEXT runtime·panicSlice3B<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3B<ABIInternal>(SB)
 TEXT runtime·panicSlice3BU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, AX
 	MOVQ	DX, BX
-#else
-	MOVQ	CX, x+0(FP)
-	MOVQ	DX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3BU<ABIInternal>(SB)
 TEXT runtime·panicSlice3C<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3C<ABIInternal>(SB)
 TEXT runtime·panicSlice3CU<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	CX, BX
-#else
-	MOVQ	AX, x+0(FP)
-	MOVQ	CX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSlice3CU<ABIInternal>(SB)
 TEXT runtime·panicSliceConvert<ABIInternal>(SB),NOSPLIT,$0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	DX, AX
-#else
-	MOVQ	DX, x+0(FP)
-	MOVQ	BX, y+8(FP)
-#endif
 	JMP	runtime·goPanicSliceConvert<ABIInternal>(SB)
 
 #ifdef GOOS_android
diff --git a/src/runtime/memclr_amd64.s b/src/runtime/memclr_amd64.s
index 6c78869f4c..918a4b9e0e 100644
--- a/src/runtime/memclr_amd64.s
+++ b/src/runtime/memclr_amd64.s
@@ -13,14 +13,9 @@
 // func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr)
 // ABIInternal for performance.
 TEXT runtime·memclrNoHeapPointers<ABIInternal>(SB), NOSPLIT, $0-16
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = ptr
 	// BX = n
 	MOVQ	AX, DI	// DI = ptr
-#else
-	MOVQ	ptr+0(FP), DI
-	MOVQ	n+8(FP), BX
-#endif
 	XORQ	AX, AX
 
 	// MOVOU seems always faster than REP STOSQ.
diff --git a/src/runtime/memmove_amd64.s b/src/runtime/memmove_amd64.s
index af538d4bce..fa0c0e414f 100644
--- a/src/runtime/memmove_amd64.s
+++ b/src/runtime/memmove_amd64.s
@@ -34,18 +34,12 @@
 // func memmove(to, from unsafe.Pointer, n uintptr)
 // ABIInternal for performance.
 TEXT runtime·memmove<ABIInternal>(SB), NOSPLIT, $0-24
-#ifdef GOEXPERIMENT_regabiargs
 	// AX = to
 	// BX = from
 	// CX = n
 	MOVQ	AX, DI
 	MOVQ	BX, SI
 	MOVQ	CX, BX
-#else
-	MOVQ	to+0(FP), DI
-	MOVQ	from+8(FP), SI
-	MOVQ	n+16(FP), BX
-#endif
 
 	// REP instructions have a high startup cost, so we handle small sizes
 	// with some straightline code. The REP MOVSQ instruction is really fast
diff --git a/src/runtime/race_amd64.s b/src/runtime/race_amd64.s
index 8a17113232..d42e415dca 100644
--- a/src/runtime/race_amd64.s
+++ b/src/runtime/race_amd64.s
@@ -46,11 +46,7 @@
 // Defined as ABIInternal so as to avoid introducing a wrapper,
 // which would render runtime.getcallerpc ineffective.
 TEXT	runtime·raceread<ABIInternal>(SB), NOSPLIT, $0-8
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	AX, RARG1
-#else
-	MOVQ	addr+0(FP), RARG1
-#endif
 	MOVQ	(SP), RARG2
 	// void __tsan_read(ThreadState *thr, void *addr, void *pc);
 	MOVQ	$__tsan_read(SB), AX
@@ -76,11 +72,7 @@ TEXT	runtime·racereadpc(SB), NOSPLIT, $0-24
 // Defined as ABIInternal so as to avoid introducing a wrapper,
 // which would render runtime.getcallerpc ineffective.
 TEXT	runtime·racewrite<ABIInternal>(SB), NOSPLIT, $0-8
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	AX, RARG1
-#else
-	MOVQ	addr+0(FP), RARG1
-#endif
 	MOVQ	(SP), RARG2
 	// void __tsan_write(ThreadState *thr, void *addr, void *pc);
 	MOVQ	$__tsan_write(SB), AX
@@ -131,13 +123,8 @@ TEXT	runtime·racereadrangepc1(SB), NOSPLIT, $0-24
 // Defined as ABIInternal so as to avoid introducing a wrapper,
 // which would render runtime.getcallerpc ineffective.
 TEXT	runtime·racewriterange<ABIInternal>(SB), NOSPLIT, $0-16
-#ifdef GOEXPERIMENT_regabiargs
 	MOVQ	AX, RARG1
 	MOVQ	BX, RARG2
-#else
-	MOVQ	addr+0(FP), RARG1
-	MOVQ	size+8(FP), RARG2
-#endif
 	MOVQ	(SP), RARG3
 	// void __tsan_write_range(ThreadState *thr, void *addr, uintptr size, void *pc);
 	MOVQ	$__tsan_write_range(SB), AX