Native implementation of coroutines to improve performance of fibers

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65834 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

coroutine/amd64/Context.h

@@ -0,0 +1,62 @@
+//
+//  amd64.h
+//  File file is part of the "Coroutine" project and released under the MIT License.
+//
+//  Created by Samuel Williams on 10/5/2018.
+//  Copyright, 2018, by Samuel Williams. All rights reserved.
+//
+
+#pragma once
+
+#include <assert.h>
+#include <string.h>
+
+#if __cplusplus
+extern "C" {
+#endif
+
+#define COROUTINE __attribute__((noreturn)) void
+
+const size_t COROUTINE_REGISTERS = 6;
+
+// The fiber context (stack pointer).
+typedef struct
+{
+	void **stack_pointer;
+} coroutine_context;
+
+// The initialization function.
+typedef void(* coroutine_start)(coroutine_context *from, coroutine_context *self);
+
+inline void coroutine_initialize(
+	coroutine_context *context,
+	coroutine_start start,
+	void *stack_pointer,
+	size_t stack_size
+) {
+	/* Force 16-byte alignment */
+	context->stack_pointer = (void**)((uintptr_t)stack_pointer & ~0xF);
+
+	if (!start) {
+		assert(!context->stack_pointer);
+		/* We are main coroutine for this thread */
+		return;
+	}
+
+	*--context->stack_pointer = NULL;
+	*--context->stack_pointer = (void*)start;
+
+	context->stack_pointer -= COROUTINE_REGISTERS;
+	memset(context->stack_pointer, 0, sizeof(void*) * COROUTINE_REGISTERS);
+}
+
+coroutine_context * coroutine_transfer(coroutine_context * current, coroutine_context * target);
+
+inline void coroutine_destroy(coroutine_context * context)
+{
+	context->stack_pointer = NULL;
+}
+
+#if __cplusplus
+}
+#endif

coroutine/amd64/Context.s

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+##
+##  amd64.c
+##  File file is part of the "Coroutine" project and released under the MIT License.
+##
+##  Created by Samuel Williams on 10/5/2018.
+##  Copyright, 2018, by Samuel Williams. All rights reserved.
+##
+
+.text
+
+.globl coroutine_transfer
+coroutine_transfer:
+
+# For older linkers
+.globl _coroutine_transfer
+_coroutine_transfer:
+
+	# Save caller state
+	pushq %rbp
+	pushq %rbx
+	pushq %r12
+	pushq %r13
+	pushq %r14
+	pushq %r15
+	
+	# Save caller stack pointer
+	movq %rsp, (%rdi)
+	
+	# Restore callee stack pointer
+	movq (%rsi), %rsp
+	
+	# Restore callee stack
+	popq %r15
+	popq %r14
+	popq %r13
+	popq %r12
+	popq %rbx
+	popq %rbp
+	
+	# Put the first argument into the return value
+	# movq %rdi, %rax
+	
+	# We pop the return address and jump to it
+	ret