cpu: o3 register renaming request handling improved

Now, prior to the renaming, the instruction requests the exact amount of
registers it will need, and the rename_map decides whether the instruction is
allowed to proceed or not.

2 files changed, 27 insertions, 2 deletions

diff --git a/src/cpu/o3/rename_impl.hh b/src/cpu/o3/rename_impl.hh
index 04a9020d7..7bf33d3ff 100644
--- a/src/cpu/o3/rename_impl.hh
+++ b/src/cpu/o3/rename_impl.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010-2012, 2014 ARM Limited
+ * Copyright (c) 2010-2012, 2014-2015 ARM Limited
  * Copyright (c) 2013 Advanced Micro Devices, Inc.
  * All rights reserved.
  *
@@ -633,7 +633,9 @@ DefaultRename<Impl>::renameInsts(ThreadID tid)
 
         // Check here to make sure there are enough destination registers
         // to rename to.  Otherwise block.
-        if (renameMap[tid]->numFreeEntries() < inst->numDestRegs()) {
+        if (!renameMap[tid]->canRename(inst->numIntDestRegs(),
+                                       inst->numFPDestRegs(),
+                                       inst->numCCDestRegs())) {
             DPRINTF(Rename, "Blocking due to lack of free "
                     "physical registers to rename to.\n");
             blockThisCycle = true;
diff --git a/src/cpu/o3/rename_map.hh b/src/cpu/o3/rename_map.hh
index 1aa3bc702..9d91f232e 100644
--- a/src/cpu/o3/rename_map.hh
+++ b/src/cpu/o3/rename_map.hh
@@ -1,4 +1,16 @@
 /*
+ * Copyright (c) 2015 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.
+ *
  * Copyright (c) 2004-2005 The Regents of The University of Michigan
  * Copyright (c) 2013 Advanced Micro Devices, Inc.
  * All rights reserved.
@@ -346,6 +358,17 @@ class UnifiedRenameMap
     {
         return std::min(intMap.numFreeEntries(), floatMap.numFreeEntries());
     }
+
+    /**
+     * Return whether there are enough registers to serve the request.
+     */
+    bool canRename(uint32_t intRegs, uint32_t floatRegs, uint32_t ccRegs) const
+    {
+        return intRegs <= intMap.numFreeEntries() &&
+            floatRegs <= floatMap.numFreeEntries() &&
+            ccRegs <= ccMap.numFreeEntries();
+    }
+
 };
 
 #endif //__CPU_O3_RENAME_MAP_HH__