From 96a67450887314cedbd9e8634ad92b76a0443779 Mon Sep 17 00:00:00 2001
From: Cherry Zhang <cherryyz@google.com>
Date: Thu, 8 Apr 2021 12:13:58 -0400
Subject: [PATCH] runtime: use register ABI in panicIndex/Slice functions

runtime.panicIndex*/panicSlice* functions move the arguments in
the right place then tail calls goPanicIndex*/Slice* using
internal ABI. (It uses internal ABI to avoid wrappers, because
the callee needs to get the caller's PC, to know whether it panics
in the runtime.) This CL makes it to use the register ABI if it
is enabled.

Change-Id: Id2ebb51b4bfb3e9aa7cb66d0a9aee63fccee5ecd
Reviewed-on: https://go-review.googlesource.com/c/go/+/308649
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
---
 src/runtime/asm_amd64.s | 70 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/src/runtime/asm_amd64.s b/src/runtime/asm_amd64.s
index cc31e5c657..77f4939b30 100644
--- a/src/runtime/asm_amd64.s
+++ b/src/runtime/asm_amd64.s
@@ -1874,68 +1874,138 @@ 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)
 
 #ifdef GOOS_android