skeleton of POWER interpeter trampoline

powerpc_interp_tramp.patch

diff --git a/mono/mini/mini-ppc.h b/mono/mini/mini-ppc.h
index 167f6ed..ff29d54 100644
--- a/mono/mini/mini-ppc.h
+++ b/mono/mini/mini-ppc.h
@@ -264,6 +264,8 @@ typedef struct MonoCompileArch {
 #endif
 #define MONO_ARCH_HAVE_OP_TAIL_CALL 1

+#define MONO_ARCH_HAVE_INTERP_PINVOKE_TRAMP
+
 #define PPC_NUM_REG_ARGS (PPC_LAST_ARG_REG-PPC_FIRST_ARG_REG+1)
 #define PPC_NUM_REG_FPARGS (PPC_LAST_FPARG_REG-PPC_FIRST_FPARG_REG+1)

@@ -330,6 +332,18 @@ typedef struct {
        int offset;
 } MonoPPCArgInfo;

+typedef struct {
+       mgreg_t gregs [MONO_SAVED_GREGS];
+       /*
+        * XXX: consistent with arm/amd64, but this might not work with AIX, so
+        * we'd need a 64-bit fp type that isn't sizeof 4 in structs for it
+        * (and I think we'd want the same for MonoLMF?)
+        */
+       gdouble fregs [MONO_SAVED_FREGS];
+       gsize stack_size;
+       gpointer stack;
+} CallContext;
+
 #ifdef PPC_USES_FUNCTION_DESCRIPTOR
 typedef struct {
        gpointer code;
diff --git a/mono/mini/tramp-ppc.c b/mono/mini/tramp-ppc.c
index 3376cc4..df622b5 100644
--- a/mono/mini/tramp-ppc.c
+++ b/mono/mini/tramp-ppc.c
@@ -25,6 +25,10 @@
 #include "mini-ppc.h"
 #include "mini-runtime.h"

+#ifndef DISABLE_INTERPRETER
+#include "interp/interp.h"
+#endif
+
 #if 0
 /* Same as mono_create_ftnptr, but doesn't require a domain */
 static gpointer
@@ -638,6 +642,26 @@ mono_arch_get_plt_info_offset (guint8 *plt_entry, mgreg_t *regs, guint8 *code)
 gpointer
 mono_arch_get_interp_to_native_trampoline (MonoTrampInfo **info)
 {
+#ifndef DISABLE_INTERPRETER
+       guint8 *start = NULL, *code;
+       guint8 *label_start_copy, *label_exit_copy;
+       MonoJumpInfo *ji = NULL;
+       GSList *unwind_ops = NULL;
+       int buf_len, i, off_methodargs, off_targetaddr;
+
+       buf_len = 512 + 1024;
+       start = code = (guint8 *) mono_global_codeman_reserve (buf_len);
+
+       /* TODO: the rest of the owl */
+
+       mono_arch_flush_icache (start, code - start);
+
+       if (info)
+               *info = mono_tramp_info_create ("interp_to_native_trampoline", start, code - start, ji, unwind_ops);
+
+       return start;
+#else
        g_assert_not_reached ();
        return NULL;
+#endif
 }