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cpu-simple: Use a local temporary for the PC in preExecute.

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This avoids having to dynamically allocate and then free a temporary
when working with the pc in preExecute.

Change-Id: Ic86e23d0f0c7e786122a6024a154bb2907a6afcb
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/52071
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
This commit is contained in:
Gabe Black
2021-10-24 23:50:05 -07:00
parent 848746b094
commit 7216fc8e29
2 changed files with 15 additions and 9 deletions
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19
src/cpu/simple/base.cc
View File

@@ -313,14 +313,15 @@ BaseSimpleCPU::preExecute()
t_info.setMemAccPredicate(true);
// decode the instruction
std::unique_ptr<PCStateBase> pc_state(thread->pcState().clone());
set(preExecuteTempPC, thread->pcState());
auto &pc_state = *preExecuteTempPC;
auto &decoder = thread->decoder;
if (isRomMicroPC(pc_state->microPC())) {
if (isRomMicroPC(pc_state.microPC())) {
t_info.stayAtPC = false;
curStaticInst = decoder.fetchRomMicroop(
pc_state->microPC(), curMacroStaticInst);
pc_state.microPC(), curMacroStaticInst);
} else if (!curMacroStaticInst) {
//We're not in the middle of a macro instruction
StaticInstPtr instPtr = NULL;
@@ -328,16 +329,16 @@ BaseSimpleCPU::preExecute()
//Predecode, ie bundle up an ExtMachInst
//If more fetch data is needed, pass it in.
Addr fetch_pc =
(pc_state->instAddr() & decoder.pcMask()) + t_info.fetchOffset;
(pc_state.instAddr() & decoder.pcMask()) + t_info.fetchOffset;
decoder.moreBytes(*pc_state, fetch_pc);
decoder.moreBytes(pc_state, fetch_pc);
//Decode an instruction if one is ready. Otherwise, we'll have to
//fetch beyond the MachInst at the current pc.
instPtr = decoder.decode(*pc_state);
instPtr = decoder.decode(pc_state);
if (instPtr) {
t_info.stayAtPC = false;
thread->pcState(*pc_state);
thread->pcState(pc_state);
} else {
t_info.stayAtPC = true;
t_info.fetchOffset += decoder.moreBytesSize();
@@ -348,13 +349,13 @@ BaseSimpleCPU::preExecute()
if (instPtr && instPtr->isMacroop()) {
curMacroStaticInst = instPtr;
curStaticInst =
curMacroStaticInst->fetchMicroop(pc_state->microPC());
curMacroStaticInst->fetchMicroop(pc_state.microPC());
} else {
curStaticInst = instPtr;
}
} else {
//Read the next micro op from the macro op
curStaticInst = curMacroStaticInst->fetchMicroop(pc_state->microPC());
curStaticInst = curMacroStaticInst->fetchMicroop(pc_state.microPC());
}
//If we decoded an instruction this "tick", record information about it.

5
src/cpu/simple/base.hh
View File

@@ -42,6 +42,9 @@
#ifndef __CPU_SIMPLE_BASE_HH__
#define __CPU_SIMPLE_BASE_HH__
#include <memory>
#include "arch/generic/pcstate.hh"
#include "base/statistics.hh"
#include "cpu/base.hh"
#include "cpu/checker/cpu.hh"
@@ -129,6 +132,8 @@ class BaseSimpleCPU : public BaseCPU
*/
void traceFault();
std::unique_ptr<PCStateBase> preExecuteTempPC;
public:
void checkForInterrupts();
void setupFetchRequest(const RequestPtr &req);