mem: Make cache terminology easier to understand

This patch changes the name of a bunch of packet flags and MSHR member
functions and variables to make the coherency protocol easier to
understand. In addition the patch adds and updates lots of
descriptions, explicitly spelling out assumptions.

The following name changes are made:

* the packet memInhibit flag is renamed to cacheResponding

* the packet sharedAsserted flag is renamed to hasSharers

* the packet NeedsExclusive attribute is renamed to NeedsWritable

* the packet isSupplyExclusive is renamed responderHadWritable

* the MSHR pendingDirty is renamed to pendingModified

The cache states, Modified, Owned, Exclusive, Shared are also called
out in the cache and MSHR code to make it easier to understand.

1 files changed, 9 insertions, 9 deletions

diff --git a/src/mem/snoop_filter.cc b/src/mem/snoop_filter.cc
index 6e8621960..b1ccc12c9 100755
--- a/src/mem/snoop_filter.cc
+++ b/src/mem/snoop_filter.cc
@@ -108,7 +108,7 @@ SnoopFilter::lookupRequest(const Packet* cpkt, const SlavePort& slave_port)
                              lookupLatency);
 
     if (cpkt->needsResponse()) {
-        if (!cpkt->memInhibitAsserted()) {
+        if (!cpkt->cacheResponding()) {
             // Max one request per address per port
             panic_if(sf_item.requested & req_port, "double request :( " \
                      "SF value %x.%x\n", sf_item.requested, sf_item.holder);
@@ -208,7 +208,7 @@ SnoopFilter::lookupSnoop(const Packet* cpkt)
     // snoops so this was never an aissue. Now that Writebacks generate snoops
     // we need to special case for Writebacks.
     assert(cpkt->isWriteback() || cpkt->req->isUncacheable() ||
-           (cpkt->isInvalidate() == cpkt->needsExclusive()));
+           (cpkt->isInvalidate() == cpkt->needsWritable()));
     if (cpkt->isInvalidate() && !sf_item.requested) {
         // Early clear of the holder, if no other request is currently going on
         // @todo: This should possibly be updated even though we do not filter
@@ -233,7 +233,7 @@ SnoopFilter::updateSnoopResponse(const Packet* cpkt,
             cpkt->cmdString());
 
     assert(cpkt->isResponse());
-    assert(cpkt->memInhibitAsserted());
+    assert(cpkt->cacheResponding());
 
     // Ultimately we should check if the packet came from an
     // allocating source, not just if the port is snooping
@@ -258,10 +258,10 @@ SnoopFilter::updateSnoopResponse(const Packet* cpkt,
              "the original request\n",  sf_item.requested, sf_item.holder);
 
     // Update the residency of the cache line.
-    if (cpkt->needsExclusive() || !cpkt->sharedAsserted()) {
-        DPRINTF(SnoopFilter, "%s:  dropping %x because needs: %i shared: %i "\
+    if (cpkt->needsWritable() || !cpkt->hasSharers()) {
+        DPRINTF(SnoopFilter, "%s: dropping %x because needs: %i writable: %i "\
                 "SF val: %x.%x\n", __func__,  rsp_mask,
-                cpkt->needsExclusive(), cpkt->sharedAsserted(),
+                cpkt->needsWritable(), !cpkt->hasSharers(),
                 sf_item.requested, sf_item.holder);
 
         sf_item.holder &= ~rsp_mask;
@@ -287,7 +287,7 @@ SnoopFilter::updateSnoopForward(const Packet* cpkt,
             cpkt->cmdString());
 
     assert(cpkt->isResponse());
-    assert(cpkt->memInhibitAsserted());
+    assert(cpkt->cacheResponding());
 
     Addr line_addr = cpkt->getBlockAddr(linesize);
     auto sf_it = cachedLocations.find(line_addr);
@@ -305,7 +305,7 @@ SnoopFilter::updateSnoopForward(const Packet* cpkt,
     // Remote (to this snoop filter) snoops update the filter
     // already when they arrive from below, because we may not see
     // any response.
-    if (cpkt->needsExclusive()) {
+    if (cpkt->needsWritable()) {
         // If the request to this snoop response hit an in-flight
         // transaction,
         // the holder was not reset -> no assertion & do that here, now!
@@ -345,7 +345,7 @@ SnoopFilter::updateResponse(const Packet* cpkt, const SlavePort& slave_port)
 
     // Update the residency of the cache line. Here we assume that the
     // line has been zapped in all caches that are not the responder.
-     if (cpkt->needsExclusive() || !cpkt->sharedAsserted())
+     if (cpkt->needsWritable() || !cpkt->hasSharers())
         sf_item.holder = 0;
     sf_item.holder |=  slave_mask;
     sf_item.requested &= ~slave_mask;