Adding upstream version 1.16.10.upstream/1.16.10upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 107 insertions, 0 deletions

diff --git a/src/runtime/rt0_js_wasm.s b/src/runtime/rt0_js_wasm.s
new file mode 100644
index 0000000..714582a
--- /dev/null
+++ b/src/runtime/rt0_js_wasm.s
@@ -0,0 +1,107 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "go_asm.h"
+#include "textflag.h"
+
+// _rt0_wasm_js is not used itself. It only exists to mark the exported functions as alive.
+TEXT _rt0_wasm_js(SB),NOSPLIT,$0
+	I32Const $wasm_export_run(SB)
+	Drop
+	I32Const $wasm_export_resume(SB)
+	Drop
+	I32Const $wasm_export_getsp(SB)
+	Drop
+
+// wasm_export_run gets called from JavaScript. It initializes the Go runtime and executes Go code until it needs
+// to wait for an event. It does NOT follow the Go ABI. It has two WebAssembly parameters:
+// R0: argc (i32)
+// R1: argv (i32)
+TEXT wasm_export_run(SB),NOSPLIT,$0
+	MOVD $runtime·wasmStack+(m0Stack__size-16)(SB), SP
+
+	Get SP
+	Get R0 // argc
+	I64ExtendI32U
+	I64Store $0
+
+	Get SP
+	Get R1 // argv
+	I64ExtendI32U
+	I64Store $8
+
+	I32Const $0 // entry PC_B
+	Call runtime·rt0_go(SB)
+	Drop
+	Call wasm_pc_f_loop(SB)
+
+	Return
+
+// wasm_export_resume gets called from JavaScript. It resumes the execution of Go code until it needs to wait for
+// an event.
+TEXT wasm_export_resume(SB),NOSPLIT,$0
+	I32Const $0
+	Call runtime·handleEvent(SB)
+	Drop
+	Call wasm_pc_f_loop(SB)
+
+	Return
+
+TEXT wasm_pc_f_loop(SB),NOSPLIT,$0
+// Call the function for the current PC_F. Repeat until PAUSE != 0 indicates pause or exit.
+// The WebAssembly stack may unwind, e.g. when switching goroutines.
+// The Go stack on the linear memory is then used to jump to the correct functions
+// with this loop, without having to restore the full WebAssembly stack.
+// It is expected to have a pending call before entering the loop, so check PAUSE first.
+	Get PAUSE
+	I32Eqz
+	If
+	loop:
+		Loop
+			// Get PC_B & PC_F from -8(SP)
+			Get SP
+			I32Const $8
+			I32Sub
+			I32Load16U $0 // PC_B
+
+			Get SP
+			I32Const $8
+			I32Sub
+			I32Load16U $2 // PC_F
+
+			CallIndirect $0
+			Drop
+
+			Get PAUSE
+			I32Eqz
+			BrIf loop
+		End
+	End
+
+	I32Const $0
+	Set PAUSE
+
+	Return
+
+// wasm_export_getsp gets called from JavaScript to retrieve the SP.
+TEXT wasm_export_getsp(SB),NOSPLIT,$0
+	Get SP
+	Return
+
+TEXT runtime·pause(SB), NOSPLIT, $0-8
+	MOVD newsp+0(FP), SP
+	I32Const $1
+	Set PAUSE
+	RETUNWIND
+
+TEXT runtime·exit(SB), NOSPLIT, $0-4
+	I32Const $0
+	Call runtime·wasmExit(SB)
+	Drop
+	I32Const $1
+	Set PAUSE
+	RETUNWIND
+
+TEXT wasm_export_lib(SB),NOSPLIT,$0
+	UNDEF