cpu: cache software/hardware breakpoint enabled status for faster exe…

…cution
JaCzekanski · Apr 22, 2020 · 2296d8c · 2296d8c
1 parent ebe8889
commit 2296d8c
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Showing 6 changed files with 42 additions and 40 deletions.
diff --git a/src/cpu/cpu.cpp b/src/cpu/cpu.cpp
@@ -32,37 +32,26 @@ void CPU::saveStateForException() {
 }
 
 void CPU::handleHardwareBreakpoints() {
-    if (cop0.dcic.codeBreakpointEnabled()) {
-        if (((PC ^ cop0.bpcm) & cop0.bpc) == 0) {
-            cop0.dcic.codeBreakpointHit = 1;
-            cop0.dcic.breakpointHit = 1;
-            instructions::exception(this, COP0::CAUSE::Exception::breakpoint);
-        }
+    if (((PC ^ cop0.bpcm) & cop0.bpc) == 0) {
+        cop0.dcic.codeBreakpointHit = 1;
+        cop0.dcic.breakpointHit = 1;
+        instructions::exception(this, COP0::CAUSE::Exception::breakpoint);
     }
 }
 
-INLINE bool CPU::handleSoftwareBreakpoints() {
-    if (breakpoints.empty()) {
-        return false;
-    }
+bool CPU::handleSoftwareBreakpoints() {
+    if (breakpoints.empty()) return false;
 
     auto bp = breakpoints.find(PC);
-    if (bp != breakpoints.end() && bp->second.enabled) {
-        if (bp->second.singleTime) {
-            breakpoints.erase(bp);
-            sys->state = System::State::pause;
-            return true;
-        }
-        if (!bp->second.hit) {
-            bp->second.hitCount++;
-            bp->second.hit = true;
-            sys->state = System::State::pause;
+    if (bp == breakpoints.end()) return false;
+    if (!bp->second.enabled) return false;
 
-            return true;
-        }
-        bp->second.hit = false;
+    bp->second.hitCount++;
+    if (bp->second.singleTime) {
+        removeBreakpoint(PC);
     }
-    return false;
+    sys->state = System::State::pause;
+    return true;
 }
 
 INLINE uint32_t CPU::fetchInstruction(uint32_t address) {
@@ -95,9 +84,10 @@ bool CPU::executeInstructions(int count) {
 
         saveStateForException();
         checkForInterrupts();
-        handleHardwareBreakpoints();
-
-        if (unlikely(handleSoftwareBreakpoints())) return false;
+        if (unlikely(breakpointsEnabled)) {
+            handleHardwareBreakpoints();
+            if (handleSoftwareBreakpoints()) return false;
+        }
 
         _opcode = Opcode(fetchInstruction(PC));
         const auto& op = instructions::OpcodeTable[_opcode.op];

diff --git a/src/cpu/cpu.h b/src/cpu/cpu.h
@@ -87,6 +87,8 @@ struct CPU {
     bool icacheEnabled;
     CacheLine icache[1024];
 
+    bool breakpointsEnabled = false;
+
     CPU(System* sys);
     void checkForInterrupts();
     INLINE void moveLoadDelaySlots();
@@ -118,7 +120,7 @@ struct CPU {
 
     void saveStateForException();
     void handleHardwareBreakpoints();
-    INLINE bool handleSoftwareBreakpoints();
+    bool handleSoftwareBreakpoints();
     INLINE uint32_t fetchInstruction(uint32_t address);
     bool executeInstructions(int count);
 
@@ -127,14 +129,24 @@ struct CPU {
     struct Breakpoint {
         bool enabled = true;
         int hitCount = 0;
-        bool hit = false;
         bool singleTime = false;
 
         Breakpoint() = default;
         Breakpoint(bool singleTime) : singleTime(singleTime) {}
     };
     std::unordered_map<uint32_t, Breakpoint> breakpoints;
 
+    // Helper
+    void addBreakpoint(uint32_t address, Breakpoint bp = Breakpoint(true)) {
+        breakpoints[address] = bp;
+        updateBreakpointsFlag();
+    }
+    void removeBreakpoint(uint32_t address) {
+        breakpoints.erase(address);
+        updateBreakpointsFlag();
+    }
+    void updateBreakpointsFlag() { breakpointsEnabled = !breakpoints.empty() || cop0.dcic.codeBreakpointEnabled(); }
+
     template <class Archive>
     void serialize(Archive& ar) {
         ar(PC, nextPC, inBranchDelay, branchTaken);

diff --git a/src/cpu/instructions.cpp b/src/cpu/instructions.cpp
@@ -574,6 +574,7 @@ void op_cop0(CPU *cpu, Opcode i) {
             // Move to co-processor zero (from cpu reg)
             // MTC0 rt, cop0.rd
             cpu->cop0.write(i.rd, cpu->reg[i.rt]);
+            cpu->updateBreakpointsFlag();
             break;
 
         case 16:

diff --git a/src/platform/headless/main.cpp b/src/platform/headless/main.cpp
@@ -17,7 +17,7 @@ int main(int argc, char **argv) {
     }
 
     // Breakpoint on BIOS Shell execution
-    cpu->breakpoints.emplace(0x80030000, mips::CPU::Breakpoint(true));
+    cpu->addBreakpoint(0x80030000);
 
     cpu->biosLog = false;
     cpu->debugOutput = false;

diff --git a/src/platform/windows/gui/debug/cpu.cpp b/src/platform/windows/gui/debug/cpu.cpp
@@ -77,7 +77,7 @@ void CPU::debuggerWindow(System* sys) {
     }
     ImGui::SameLine();
     if (ImGui::Button("Step over")) {
-        sys->cpu->breakpoints.emplace(sys->cpu->PC + 4, mips::CPU::Breakpoint(true));
+        sys->cpu->addBreakpoint(sys->cpu->PC + 4);
         sys->state = System::State::run;
     }
     ImGui::SameLine();
@@ -229,9 +229,9 @@ void CPU::debuggerWindow(System* sys) {
                                       .c_str())) {
                 auto bp = sys->cpu->breakpoints.find(address);
                 if (bp == sys->cpu->breakpoints.end()) {
-                    sys->cpu->breakpoints.emplace(address, mips::CPU::Breakpoint());
+                    sys->cpu->addBreakpoint(address, {});
                 } else {
-                    sys->cpu->breakpoints.erase(bp);
+                    sys->cpu->removeBreakpoint(address);
                 }
             }
 
@@ -256,13 +256,12 @@ void CPU::debuggerWindow(System* sys) {
         auto breakpointExist = bp != sys->cpu->breakpoints.end();
 
         if (ImGui::Selectable("Run to line")) {
-            sys->cpu->breakpoints.emplace(contextMenuAddress, mips::CPU::Breakpoint(true));
+            sys->cpu->addBreakpoint(contextMenuAddress);
             sys->state = System::State::run;
         }
 
-        if (breakpointExist && ImGui::Selectable("Remove breakpoint")) sys->cpu->breakpoints.erase(bp);
-        if (!breakpointExist && ImGui::Selectable("Add breakpoint"))
-            sys->cpu->breakpoints.emplace(contextMenuAddress, mips::CPU::Breakpoint());
+        if (breakpointExist && ImGui::Selectable("Remove breakpoint")) sys->cpu->removeBreakpoint(contextMenuAddress);
+        if (!breakpointExist && ImGui::Selectable("Add breakpoint")) sys->cpu->addBreakpoint(contextMenuAddress, {});
 
         ImGui::EndPopup();
     }
@@ -335,7 +334,7 @@ void CPU::breakpointsWindow(System* sys) {
     if (ImGui::BeginPopupContextItem("breakpoint_menu")) {
         auto breakpointExist = sys->cpu->breakpoints.find(selectedBreakpoint) != sys->cpu->breakpoints.end();
 
-        if (breakpointExist && ImGui::Selectable("Remove")) sys->cpu->breakpoints.erase(selectedBreakpoint);
+        if (breakpointExist && ImGui::Selectable("Remove")) sys->cpu->removeBreakpoint(selectedBreakpoint);
         if (ImGui::Selectable("Add")) showPopup = true;
 
         ImGui::EndPopup();
@@ -351,7 +350,7 @@ void CPU::breakpointsWindow(System* sys) {
         ImGui::PushItemWidth(80);
         if (ImGui::InputText("", addressInput, 10, ImGuiInputTextFlags_CharsHexadecimal | ImGuiInputTextFlags_EnterReturnsTrue)
             && sscanf(addressInput, "%x", &address) == 1) {
-            sys->cpu->breakpoints.emplace(address, mips::CPU::Breakpoint());
+            sys->cpu->addBreakpoint(address, {});
             ImGui::CloseCurrentPopup();
         }
         ImGui::PopItemWidth();

diff --git a/src/system_tools.cpp b/src/system_tools.cpp
@@ -16,7 +16,7 @@ void bootstrap(std::unique_ptr<System>& sys) {
     sys->loadBios(config.bios);
 
     // Breakpoint on BIOS Shell execution
-    sys->cpu->breakpoints.emplace(0x80030000, mips::CPU::Breakpoint(true));
+    sys->cpu->addBreakpoint(0x80030000);
 
     // Execute BIOS till breakpoint hit (shell is about to be executed)
     while (sys->state == System::State::run) sys->emulateFrame();