[dev.typeparams] all: always enable regabig on AMD64

Always enable regabig on AMD64, which enables the G register and
the X15 zero register. Remove the fallback path.

Also remove the regabig GOEXPERIMENT. On AMD64 it is always
enabled (this CL). Other architectures already have a G register,
except for 386, where there are too few registers and it is
unlikely that we will reserve one. (If we really do, we can just
add a new experiment).

Change-Id: I229cac0060f48fe58c9fdaabd38d6fa16b8a0855
Reviewed-on: https://go-review.googlesource.com/c/go/+/327272
Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Go Bot <gobot@golang.org>

6 files changed, 0 insertions, 67 deletions

diff --git a/src/runtime/asm_amd64.s b/src/runtime/asm_amd64.s
index f8f5fc62e6..50ffa30ac5 100644
--- a/src/runtime/asm_amd64.s
+++ b/src/runtime/asm_amd64.s
@@ -683,10 +683,6 @@ TEXT runtime·jmpdefer(SB), NOSPLIT, $0-16
 // or else unwinding from systemstack_switch is incorrect.
 // Smashes R9.
 TEXT gosave_systemstack_switch<>(SB),NOSPLIT,$0
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R14)
-	MOVQ	g(R14), R14
-#endif
 	MOVQ	$runtime·systemstack_switch(SB), R9
 	MOVQ	R9, (g_sched+gobuf_pc)(R14)
 	LEAQ	8(SP), R9
@@ -1284,10 +1280,8 @@ aes65to128:
 	PXOR	X10, X8
 	PXOR	X11, X9
 	PXOR	X9, X8
-#ifdef GOEXPERIMENT_regabig
 	// X15 must be zero on return
 	PXOR	X15, X15
-#endif
 #ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X8, AX	// return X8
 #else
@@ -1408,10 +1402,8 @@ aesloop:
 	PXOR	X10, X8
 	PXOR	X11, X9
 	PXOR	X9, X8
-#ifdef GOEXPERIMENT_regabig
 	// X15 must be zero on return
 	PXOR	X15, X15
-#endif
 #ifdef GOEXPERIMENT_regabiargs
 	MOVQ	X8, AX	// return X8
 #else
@@ -1595,13 +1587,11 @@ TEXT runtime·addmoduledata(SB),NOSPLIT,$0-0
 // signals. It is quite painful to set X15 in the signal context,
 // so we do it here.
 TEXT ·sigpanic0(SB),NOSPLIT,$0-0
-#ifdef GOEXPERIMENT_regabig
 	get_tls(R14)
 	MOVQ	g(R14), R14
 #ifndef GOOS_plan9
 	XORPS	X15, X15
 #endif
-#endif
 	JMP	·sigpanic<ABIInternal>(SB)
 
 // gcWriteBarrier performs a heap pointer write and informs the GC.
@@ -1619,13 +1609,7 @@ TEXT runtime·gcWriteBarrier<ABIInternal>(SB),NOSPLIT,$112
 	MOVQ	R13, 104(SP)
 	// TODO: Consider passing g.m.p in as an argument so they can be shared
 	// across a sequence of write barriers.
-#ifdef GOEXPERIMENT_regabig
 	MOVQ	g_m(R14), R13
-#else
-	get_tls(R13)
-	MOVQ	g(R13), R13
-	MOVQ	g_m(R13), R13
-#endif
 	MOVQ	m_p(R13), R13
 	MOVQ	(p_wbBuf+wbBuf_next)(R13), R12
 	// Increment wbBuf.next position.
diff --git a/src/runtime/memclr_amd64.s b/src/runtime/memclr_amd64.s
index a10f57bd8c..6c78869f4c 100644
--- a/src/runtime/memclr_amd64.s
+++ b/src/runtime/memclr_amd64.s
@@ -37,9 +37,6 @@ tail:
 	JE	_8
 	CMPQ	BX, $16
 	JBE	_9through16
-#ifndef GOEXPERIMENT_regabig
-	PXOR	X15, X15
-#endif
 	CMPQ	BX, $32
 	JBE	_17through32
 	CMPQ	BX, $64
diff --git a/src/runtime/memmove_amd64.s b/src/runtime/memmove_amd64.s
index 24c6529f58..af538d4bce 100644
--- a/src/runtime/memmove_amd64.s
+++ b/src/runtime/memmove_amd64.s
@@ -254,10 +254,8 @@ move_129through256:
 	MOVOU	X13, -48(DI)(BX*1)
 	MOVOU	X14, -32(DI)(BX*1)
 	MOVOU	X15, -16(DI)(BX*1)
-#ifdef GOEXPERIMENT_regabig
 	// X15 must be zero on return
 	PXOR	X15, X15
-#endif
 	RET
 move_256through2048:
 	SUBQ	$256, BX
@@ -297,10 +295,8 @@ move_256through2048:
 	LEAQ	256(SI), SI
 	LEAQ	256(DI), DI
 	JGE	move_256through2048
-#ifdef GOEXPERIMENT_regabig
 	// X15 must be zero on return
 	PXOR	X15, X15
-#endif
 	JMP	tail
 
 avxUnaligned:
diff --git a/src/runtime/race_amd64.s b/src/runtime/race_amd64.s
index 469623ff20..8a17113232 100644
--- a/src/runtime/race_amd64.s
+++ b/src/runtime/race_amd64.s
@@ -161,10 +161,6 @@ TEXT	runtime·racewriterangepc1(SB), NOSPLIT, $0-24
 // If addr (RARG1) is out of range, do nothing.
 // Otherwise, setup goroutine context and invoke racecall. Other arguments already set.
 TEXT	racecalladdr<>(SB), NOSPLIT, $0-0
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	// Check that addr is within [arenastart, arenaend) or within [racedatastart, racedataend).
 	CMPQ	RARG1, runtime·racearenastart(SB)
@@ -192,10 +188,6 @@ TEXT	runtime·racefuncenter(SB), NOSPLIT, $0-8
 // R11 = caller's return address
 TEXT	racefuncenter<>(SB), NOSPLIT, $0-0
 	MOVQ	DX, BX		// save function entry context (for closures)
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	MOVQ	R11, RARG1
 	// void __tsan_func_enter(ThreadState *thr, void *pc);
@@ -208,10 +200,6 @@ TEXT	racefuncenter<>(SB), NOSPLIT, $0-0
 // func runtime·racefuncexit()
 // Called from instrumented code.
 TEXT	runtime·racefuncexit(SB), NOSPLIT, $0-0
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	// void __tsan_func_exit(ThreadState *thr);
 	MOVQ	$__tsan_func_exit(SB), AX
@@ -370,10 +358,6 @@ racecallatomic_data:
 	JAE	racecallatomic_ignore
 racecallatomic_ok:
 	// Addr is within the good range, call the atomic function.
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	MOVQ	8(SP), RARG1	// caller pc
 	MOVQ	(SP), RARG2	// pc
@@ -385,10 +369,6 @@ racecallatomic_ignore:
 	// An attempt to synchronize on the address would cause crash.
 	MOVQ	AX, BX	// remember the original function
 	MOVQ	$__tsan_go_ignore_sync_begin(SB), AX
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	CALL	racecall<>(SB)
 	MOVQ	BX, AX	// restore the original function
@@ -416,10 +396,6 @@ TEXT	runtime·racecall(SB), NOSPLIT, $0-0
 
 // Switches SP to g0 stack and calls (AX). Arguments already set.
 TEXT	racecall<>(SB), NOSPLIT, $0-0
-#ifndef GOEXPERIMENT_regabig
-	get_tls(R12)
-	MOVQ	g(R12), R14
-#endif
 	MOVQ	g_m(R14), R13
 	// Switch to g0 stack.
 	MOVQ	SP, R12		// callee-saved, preserved across the CALL
diff --git a/src/runtime/sys_linux_amd64.s b/src/runtime/sys_linux_amd64.s
index f22b7ad928..64ddc2354e 100644
--- a/src/runtime/sys_linux_amd64.s
+++ b/src/runtime/sys_linux_amd64.s
@@ -215,13 +215,7 @@ TEXT runtime·nanotime1(SB),NOSPLIT,$16-8
 
 	MOVQ	SP, R12	// Save old SP; R12 unchanged by C code.
 
-#ifdef GOEXPERIMENT_regabig
 	MOVQ	g_m(R14), BX // BX unchanged by C code.
-#else
-	get_tls(CX)
-	MOVQ	g(CX), AX
-	MOVQ	g_m(AX), BX // BX unchanged by C code.
-#endif
 
 	// Set vdsoPC and vdsoSP for SIGPROF traceback.
 	// Save the old values on stack and restore them on exit,
@@ -236,11 +230,7 @@ TEXT runtime·nanotime1(SB),NOSPLIT,$16-8
 	MOVQ	CX, m_vdsoPC(BX)
 	MOVQ	DX, m_vdsoSP(BX)
 
-#ifdef GOEXPERIMENT_regabig
 	CMPQ	R14, m_curg(BX)	// Only switch if on curg.
-#else
-	CMPQ	AX, m_curg(BX)	// Only switch if on curg.
-#endif
 	JNE	noswitch
 
 	MOVQ	m_g0(BX), DX
diff --git a/src/runtime/time_linux_amd64.s b/src/runtime/time_linux_amd64.s
index 0dd7919896..c88e92bd0c 100644
--- a/src/runtime/time_linux_amd64.s
+++ b/src/runtime/time_linux_amd64.s
@@ -15,13 +15,7 @@
 TEXT time·now(SB),NOSPLIT,$16-24
 	MOVQ	SP, R12 // Save old SP; R12 unchanged by C code.
 
-#ifdef GOEXPERIMENT_regabig
 	MOVQ	g_m(R14), BX // BX unchanged by C code.
-#else
-	get_tls(CX)
-	MOVQ	g(CX), AX
-	MOVQ	g_m(AX), BX // BX unchanged by C code.
-#endif
 
 	// Store CLOCK_REALTIME results directly to return space.
 	LEAQ	sec+0(FP), SI
@@ -38,11 +32,7 @@ TEXT time·now(SB),NOSPLIT,$16-24
 	MOVQ	CX, m_vdsoPC(BX)
 	MOVQ	SI, m_vdsoSP(BX)
 
-#ifdef GOEXPERIMENT_regabig
 	CMPQ	R14, m_curg(BX)	// Only switch if on curg.
-#else
-	CMPQ	AX, m_curg(BX)	// Only switch if on curg.
-#endif
 	JNE	noswitch
 
 	MOVQ	m_g0(BX), DX