cpu,mem: Add support for partial loads/stores and wide mem. accesses

This changeset adds support for partial (or masked) loads/stores, i.e.
loads/stores that can disable accesses to individual bytes within the
target address range.  In addition, this changeset extends the code to
crack memory accesses across most CPU models (TimingSimpleCPU still
TBD), so that arbitrarily wide memory accesses are supported.  These
changes are required for supporting ISAs with wide vectors.

Additional authors:
- Gabor Dozsa <gabor.dozsa@arm.com>
- Tiago Muck <tiago.muck@arm.com>

Change-Id: Ibad33541c258ad72925c0b1d5abc3e5e8bf92d92
Signed-off-by: Giacomo Gabrielli <giacomo.gabrielli@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/13518
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

1 files changed, 96 insertions, 0 deletions

diff --git a/src/cpu/utils.hh b/src/cpu/utils.hh
new file mode 100644
index 000000000..4c1318174
--- /dev/null
+++ b/src/cpu/utils.hh
@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2017-2018 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Andrew Bardsley
+ */
+
+#ifndef __CPU_UTILS_HH__
+#define __CPU_UTILS_HH__
+
+#include "base/types.hh"
+
+/**
+ * Calculates the offset of a given address wrt aligned fixed-size blocks.
+ * @param addr Input address.
+ * @param block_size Block size in bytes.
+ * @return Offset of the given address in bytes.
+ */
+inline Addr
+addrBlockOffset(Addr addr, Addr block_size)
+{
+    return addr & (block_size - 1);
+}
+
+/**
+ * Returns the address of the closest aligned fixed-size block to the given
+ * address.
+ * @param addr Input address.
+ * @param block_size Block size in bytes.
+ * @return Address of the closest aligned block.
+ */
+inline Addr
+addrBlockAlign(Addr addr, Addr block_size)
+{
+    return addr & ~(block_size - 1);
+}
+
+/**
+ * Returns true if the given memory access (address, size) needs to be
+ * fragmented across aligned fixed-size blocks.
+ * @param addr Address of the memory access.
+ * @param size Size of the memory access.
+ * @param block_size Block size in bytes.
+ * @return True if the memory access needs to be fragmented.
+ */
+inline bool
+transferNeedsBurst(Addr addr, unsigned int size, unsigned int block_size)
+{
+    return (addrBlockOffset(addr, block_size) + size) > block_size;
+}
+
+/**
+ * Test if there is any active element in an enablement range.
+ */
+inline bool
+isAnyActiveElement(const std::vector<bool>::const_iterator& it_start,
+                   const std::vector<bool>::const_iterator& it_end)
+{
+    auto it_tmp = it_start;
+    for (;it_tmp != it_end && !(*it_tmp); ++it_tmp);
+    return (it_tmp != it_end);
+}
+
+#endif // __CPU_UTILS_HH__