Ruby31: add support for Darwin ppc/ppc64 (#5927)

* add coroutines for ppc & ppc64

* fix universal coroutine to include ppc & ppc64

* add powerpc*-darwin to configure.ac

* fix thread_pthread for older systems

2 files changed, 130 insertions, 0 deletions

diff --git a/coroutine/ppc/Context.S b/coroutine/ppc/Context.S
new file mode 100644
index 0000000000..fe28390df0
--- /dev/null
+++ b/coroutine/ppc/Context.S
@@ -0,0 +1,73 @@
+#define TOKEN_PASTE(x,y) x##y
+#define PREFIXED_SYMBOL(prefix,name) TOKEN_PASTE(prefix,name)
+
+.text
+.align 2
+
+.globl PREFIXED_SYMBOL(SYMBOL_PREFIX,coroutine_transfer)
+PREFIXED_SYMBOL(SYMBOL_PREFIX,coroutine_transfer):
+	# Make space on the stack for caller registers
+	addi r1,r1,-80
+
+	# Save caller registers
+	stw r13,0(r1)
+	stw r14,4(r1)
+	stw r15,8(r1)
+	stw r16,12(r1)
+	stw r17,16(r1)
+	stw r18,20(r1)
+	stw r19,24(r1)
+	stw r20,28(r1)
+	stw r21,32(r1)
+	stw r22,36(r1)
+	stw r23,40(r1)
+	stw r24,44(r1)
+	stw r25,48(r1)
+	stw r26,52(r1)
+	stw r27,56(r1)
+	stw r28,60(r1)
+	stw r29,64(r1)
+	stw r30,68(r1)
+	stw r31,72(r1)
+
+	# Save return address
+	mflr r0
+	stw r0,76(r1)
+
+	# Save stack pointer to first argument
+	stw r1,0(r3)
+
+	# Load stack pointer from second argument
+	lwz r1,0(r4)
+
+	# Restore caller registers
+	lwz r13,0(r1)
+	lwz r14,4(r1)
+	lwz r15,8(r1)
+	lwz r16,12(r1)
+	lwz r17,16(r1)
+	lwz r18,20(r1)
+	lwz r19,24(r1)
+	lwz r20,28(r1)
+	lwz r21,32(r1)
+	lwz r22,36(r1)
+	lwz r23,40(r1)
+	lwz r24,44(r1)
+	lwz r25,48(r1)
+	lwz r26,52(r1)
+	lwz r27,56(r1)
+	lwz r28,60(r1)
+	lwz r29,64(r1)
+	lwz r30,68(r1)
+	lwz r31,72(r1)
+
+	# Load return address
+	lwz r0,76(r1)
+	mtlr r0
+
+	# Pop stack frame
+	addi r1,r1,80
+
+	# Jump to return address
+	blr
+
diff --git a/coroutine/ppc/Context.h b/coroutine/ppc/Context.h
new file mode 100644
index 0000000000..9f69390388
--- /dev/null
+++ b/coroutine/ppc/Context.h
@@ -0,0 +1,57 @@
+#ifndef COROUTINE_PPC_CONTEXT_H
+#define COROUTINE_PPC_CONTEXT_H 1
+
+#pragma once
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#define COROUTINE __attribute__((noreturn)) void
+
+enum {
+  COROUTINE_REGISTERS =
+  20  /* 19 general purpose registers (r13–r31) and 1 return address */
+  + 4  /* space for fiber_entry() to store the link register */
+};
+
+struct coroutine_context
+{
+    void **stack_pointer;
+    void *argument;
+};
+
+typedef COROUTINE(* coroutine_start)(struct coroutine_context *from, struct coroutine_context *self);
+
+static inline void coroutine_initialize_main(struct coroutine_context * context) {
+    context->stack_pointer = NULL;
+}
+
+static inline void coroutine_initialize(
+    struct coroutine_context *context,
+    coroutine_start start,
+    void *stack,
+    size_t size
+) {
+    assert(start && stack && size >= 1024);
+
+    // Stack grows down. Force 16-byte alignment.
+    char * top = (char*)stack + size;
+    context->stack_pointer = (void**)((uintptr_t)top & ~0xF);
+
+    context->stack_pointer -= COROUTINE_REGISTERS;
+    memset(context->stack_pointer, 0, sizeof(void*) * COROUTINE_REGISTERS);
+
+    /* Skip a global prologue that sets the TOC register */
+    context->stack_pointer[19] = ((char*)start) + 8;
+}
+
+struct coroutine_context * coroutine_transfer(struct coroutine_context * current, struct coroutine_context * target);
+
+static inline void coroutine_destroy(struct coroutine_context * context)
+{
+    context->stack_pointer = NULL;
+}
+
+#endif /* COROUTINE_PPC_CONTEXT_H */