class TimingSimpleCPU;
class InorderCPU;
class SymbolTable;
+class AddrDecodePage;
namespace Trace {
class InstRecord;
: StaticInstBase(__opClass),
machInst(_machInst), mnemonic(_mnemonic), cachedDisassembly(0)
{
+ memset(&recentDecodes, 0, 2 * sizeof(cacheElement));
}
public:
/// Decode a machine instruction.
/// @param mach_inst The binary instruction to decode.
/// @retval A pointer to the corresponding StaticInst object.
- //This is defined as inline below.
- static StaticInstPtr decode(ExtMachInst mach_inst);
+ //This is defined as inlined below.
+ static StaticInstPtr decode(ExtMachInst mach_inst, Addr addr);
/// Return name of machine instruction
std::string getName() { return mnemonic; }
+
+ /// Decoded instruction cache type, for address decoding.
+ /// A generic hash_map is used.
+ typedef m5::hash_map<Addr, AddrDecodePage *> AddrDecodeCache;
+
+ /// A cache of decoded instruction objects from addresses.
+ static AddrDecodeCache addrDecodeCache;
+
+ struct cacheElement {
+ Addr page_addr;
+ AddrDecodePage *decodePage;
+ } ;
+
+ /// An array of recently decoded instructions.
+ // might not use an array if there is only two elements
+ static struct cacheElement recentDecodes[2];
+
+ /// Updates the recently decoded instructions entries
+ /// @param page_addr The page address recently used.
+ /// @param decodePage Pointer to decoding page containing the decoded
+ /// instruction.
+ static inline void
+ updateCache(Addr page_addr, AddrDecodePage *decodePage)
+ {
+ recentDecodes[1].page_addr = recentDecodes[0].page_addr;
+ recentDecodes[1].decodePage = recentDecodes[0].decodePage;
+ recentDecodes[0].page_addr = page_addr;
+ recentDecodes[0].decodePage = decodePage;
+ }
+
+ /// Searches the decoded instruction cache for instruction decoding.
+ /// If it is not found, then we decode the instruction.
+ /// Otherwise, we get the instruction from the cache and move it into
+ /// the address-to-instruction decoding page.
+ /// @param mach_inst The binary instruction to decode.
+ /// @param addr The address that contained the binary instruction.
+ /// @param decodePage Pointer to decoding page containing the instruction.
+ /// @retval A pointer to the corresponding StaticInst object.
+ //This is defined as inlined below.
+ static StaticInstPtr searchCache(ExtMachInst mach_inst, Addr addr,
+ AddrDecodePage * decodePage);
};
typedef RefCountingPtr<StaticInstBase> StaticInstBasePtr;
/// Construct directly from machine instruction.
/// Calls StaticInst::decode().
- explicit StaticInstPtr(TheISA::ExtMachInst mach_inst)
- : RefCountingPtr<StaticInst>(StaticInst::decode(mach_inst))
+ explicit StaticInstPtr(TheISA::ExtMachInst mach_inst, Addr addr)
+ : RefCountingPtr<StaticInst>(StaticInst::decode(mach_inst, addr))
{
}
}
};
+/// A page of a list of decoded instructions from an address.
+class AddrDecodePage
+{
+ typedef TheISA::ExtMachInst ExtMachInst;
+ protected:
+ StaticInstPtr instructions[TheISA::PageBytes];
+ bool valid[TheISA::PageBytes];
+ Addr lowerMask;
+
+ public:
+ /// Constructor
+ AddrDecodePage() {
+ lowerMask = TheISA::PageBytes - 1;
+ memset(valid, 0, TheISA::PageBytes);
+ }
+
+ /// Checks if the instruction is already decoded and the machine
+ /// instruction in the cache matches the current machine instruction
+ /// related to the address
+ /// @param mach_inst The binary instruction to check
+ /// @param addr The address containing the instruction
+ inline bool decoded(ExtMachInst mach_inst, Addr addr)
+ {
+ return (valid[addr & lowerMask] &&
+ (instructions[addr & lowerMask]->machInst == mach_inst));
+ }
+
+ /// Returns the instruction object. decoded should be called first
+ /// to check if the instruction is valid.
+ /// @param addr The address of the instruction.
+ /// @retval A pointer to the corresponding StaticInst object.
+ inline StaticInstPtr getInst(Addr addr)
+ { return instructions[addr & lowerMask]; }
+
+ /// Inserts a pointer to a StaticInst object into the list of decoded
+ /// instructions on the page.
+ /// @param addr The address of the instruction.
+ /// @param si A pointer to the corresponding StaticInst object.
+ inline void insert(Addr addr, StaticInstPtr &si)
+ {
+ instructions[addr & lowerMask] = si;
+ valid[addr & lowerMask] = true;
+ }
+
+};
+
+
inline StaticInstPtr
-StaticInst::decode(StaticInst::ExtMachInst mach_inst)
+StaticInst::decode(StaticInst::ExtMachInst mach_inst, Addr addr)
{
#ifdef DECODE_CACHE_HASH_STATS
// Simple stats on decode hash_map. Turns out the default
}
#endif
+ Addr page_addr = addr & ~(TheISA::PageBytes - 1);
+
+ // checks recently decoded addresses
+ if (recentDecodes[0].decodePage &&
+ page_addr == recentDecodes[0].page_addr) {
+ if (recentDecodes[0].decodePage->decoded(mach_inst, addr))
+ return recentDecodes[0].decodePage->getInst(addr);
+
+ return searchCache(mach_inst, addr, recentDecodes[0].decodePage);
+ }
+
+ if (recentDecodes[1].decodePage &&
+ page_addr == recentDecodes[1].page_addr) {
+ if (recentDecodes[1].decodePage->decoded(mach_inst, addr))
+ return recentDecodes[1].decodePage->getInst(addr);
+
+ return searchCache(mach_inst, addr, recentDecodes[1].decodePage);
+ }
+
+ // searches the page containing the address to decode
+ AddrDecodeCache::iterator iter = addrDecodeCache.find(page_addr);
+ if (iter != addrDecodeCache.end()) {
+ updateCache(page_addr, iter->second);
+ if (iter->second->decoded(mach_inst, addr))
+ return iter->second->getInst(addr);
+
+ return searchCache(mach_inst, addr, iter->second);
+ }
+
+ // creates a new object for a page of decoded instructions
+ AddrDecodePage * decodePage = new AddrDecodePage;
+ addrDecodeCache[page_addr] = decodePage;
+ updateCache(page_addr, decodePage);
+ return searchCache(mach_inst, addr, decodePage);
+}
+
+inline StaticInstPtr
+StaticInst::searchCache(ExtMachInst mach_inst, Addr addr,
+ AddrDecodePage * decodePage)
+{
DecodeCache::iterator iter = decodeCache.find(mach_inst);
if (iter != decodeCache.end()) {
+ decodePage->insert(addr, iter->second);
return iter->second;
}
StaticInstPtr si = TheISA::decodeInst(mach_inst);
+ decodePage->insert(addr, si);
decodeCache[mach_inst] = si;
return si;
}
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