sim: Make the page shift a member of the MemPool class.

Pass it in through the constructor, rather than have the MemPool call
into the System object every time it needs the page shift. This is
simpler, more efficient, and removes a dependency between the MemPool
class and the System class.

Change-Id: I059bcb0db249251b32bff1beba3eadfe306d9081
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/50339
Reviewed-by: Matthew Poremba <matthew.poremba@amd.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/sim/mem_pool.cc

@@ -33,14 +33,14 @@
 
 #include "sim/mem_pool.hh"
 
-#include "sim/system.hh"
+#include "base/logging.hh"
 
 namespace gem5
 {
 
-MemPool::MemPool(System *system, Addr ptr, Addr limit)
-        : sys(system), freePageNum(ptr >> sys->getPageShift()),
-        _totalPages(limit >> sys->getPageShift())
+MemPool::MemPool(Addr page_shift, Addr ptr, Addr limit)
+        : pageShift(page_shift), freePageNum(ptr >> page_shift),
+        _totalPages(limit >> page_shift)
 {
 }
 
@@ -59,7 +59,7 @@ MemPool::setFreePage(Counter value)
 Addr
 MemPool::freePageAddr() const
 {
-    return freePageNum << sys->getPageShift();
+    return freePageNum << pageShift;
 }
 
 Counter
@@ -83,19 +83,19 @@ MemPool::freePages() const
 Addr
 MemPool::allocatedBytes() const
 {
-    return allocatedPages() << sys->getPageShift();
+    return allocatedPages() << pageShift;
 }
 
 Addr
 MemPool::freeBytes() const
 {
-    return freePages() << sys->getPageShift();
+    return freePages() << pageShift;
 }
 
 Addr
 MemPool::totalBytes() const
 {
-    return totalPages() << sys->getPageShift();
+    return totalPages() << pageShift;
 }
 
 Addr

src/sim/mem_pool.hh

@@ -45,7 +45,7 @@ class System;
 class MemPool
 {
   private:
-    System *sys;
+    Addr pageShift;
 
     /** Page number to free memory. */
     Counter freePageNum;
@@ -54,7 +54,7 @@ class MemPool
     Counter _totalPages;
 
   public:
-    MemPool(System *system, Addr ptr, Addr limit);
+    MemPool(Addr page_shift, Addr ptr, Addr limit);
 
     Counter freePage() const;
     void setFreePage(Counter value);

src/sim/system.cc

@@ -236,9 +236,10 @@ System::System(const Params &p)
             if (_m5opRange.valid()) {
                 // Make sure the m5op range is not included.
                 for (const auto &range: mem.exclude({_m5opRange}))
-                    memPools.emplace_back(this, range.start(), range.end());
+                    memPools.emplace_back(getPageShift(),
+                            range.start(), range.end());
             } else {
-                memPools.emplace_back(this, mem.start(), mem.end());
+                memPools.emplace_back(getPageShift(), mem.start(), mem.end());
             }
         }
 
@@ -468,7 +469,7 @@ System::unserialize(CheckpointIn &cp)
 
     assert(ptrs.size() == limits.size());
     for (size_t i = 0; i < ptrs.size(); i++)
-        memPools.emplace_back(this, ptrs[i], limits[i]);
+        memPools.emplace_back(getPageShift(), ptrs[i], limits[i]);
 
     // also unserialize the memories in the system
     physmem.unserializeSection(cp, "physmem");