ircd::simt: Add preliminary memory characteristics tool.

include/ircd/simt/mem.h

@@ -0,0 +1,76 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2022 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_SIMT_MEM_H
+
+#if defined(__OPENCL_VERSION__)
+__constant
+struct ircd_simt_mem
+{
+	const uint
+	local_bank_width,      ///< Bytes per bank
+	local_banks;           ///< Banks per unit
+
+	const uint
+	global_bank_width,     ///< Bytes per bank
+	global_chan_banks,     ///< Banks per channel
+	global_chans;          ///< Channels per device
+}
+ircd_simt_mem = //TODO: XXX get values better
+{
+	.local_bank_width = 4,
+	.local_banks = 32,
+
+	.global_bank_width = 256,
+
+	#if defined(__AMDDNA__)
+		.global_chan_banks = 4,
+	#else
+		.global_chan_banks = 1,
+	#endif
+
+	#if defined(__AMDDNA__)
+		.global_chans = 64,
+	#elif defined(__AMDGCN__)
+		.global_chans = 12,
+	#elif defined(__R600__)
+		.global_chans = 8,
+	#else
+		.global_chans = 1,
+	#endif
+};
+#endif
+
+#if defined(__OPENCL_VERSION__)
+/// Given a global pointer, determines the memory channel and bank within that
+/// channel returned as a ushort2: [0] = channel, [1] = bank.
+static ushort2
+ircd_simt_mem_chan_bank(__global const void *const ptr)
+{
+	const uint
+	global_chan_width = ircd_simt_mem.global_chan_banks * ircd_simt_mem.global_bank_width,
+	global_cache_width = ircd_simt_mem.global_chans * global_chan_width;
+
+	const uintptr_t
+	uptr = (uintptr_t)ptr,
+	cb = uptr % global_cache_width;
+
+	const ushort
+	chan = cb / global_chan_width,
+	coff = cb % global_chan_width,
+	bank = coff / ircd_simt_mem.global_bank_width;
+
+	return (ushort2)
+	{
+		chan, bank
+	};
+}
+#endif

include/ircd/simt/simt.h

@@ -14,6 +14,7 @@
 #include "portable.h"
 #include "assert.h"
 #include "cycles.h"
+#include "mem.h"
 #include "math.h"
 #include "hadd.h"
 #include "broadcast.h"