UserspaceEmulator: Devirtualize read/write/execute region permissions

These are getting quite hot (~4% of general emulation profile combined)
so let's just devirtualize them and turn the function calls into simple
boolean checks.

DevTools/UserspaceEmulator/MmapRegion.cpp

@@ -50,8 +50,8 @@ NonnullOwnPtr<MmapRegion> MmapRegion::create_file_backed(u32 base, u32 size, u32
 
 MmapRegion::MmapRegion(u32 base, u32 size, int prot)
     : Region(base, size)
-    , m_prot(prot)
 {
+    set_prot(prot);
     m_shadow_data = (u8*)malloc(size);
     memset(m_shadow_data, 1, size);
 }

DevTools/UserspaceEmulator/MmapRegion.h

@@ -53,14 +53,15 @@ public:
     virtual u8* data() override { return m_data; }
     virtual u8* shadow_data() override { return m_shadow_data; }
 
-    virtual bool is_readable() const override { return m_prot & PROT_READ; }
-    virtual bool is_writable() const override { return m_prot & PROT_WRITE; }
-    virtual bool is_executable() const override { return m_prot & PROT_EXEC; }
-
     bool is_malloc_block() const { return m_malloc; }
     void set_malloc(bool b) { m_malloc = b; }
 
-    void set_prot(int prot) { m_prot = prot; }
+    void set_prot(int prot)
+    {
+        set_readable(prot & PROT_READ);
+        set_writable(prot & PROT_WRITE);
+        set_executable(prot & PROT_EXEC);
+    }
 
     MallocRegionMetadata* malloc_metadata() { return m_malloc_metadata; }
     void set_malloc_metadata(Badge<MallocTracer>, NonnullOwnPtr<MallocRegionMetadata> metadata) { m_malloc_metadata = move(metadata); }
@@ -71,7 +72,6 @@ private:
 
     u8* m_data { nullptr };
     u8* m_shadow_data { nullptr };
-    int m_prot { 0 };
     bool m_file_backed { false };
     bool m_malloc { false };
 

DevTools/UserspaceEmulator/SoftMMU.h

@@ -69,9 +69,13 @@ public:
         bool is_text() const { return m_text; }
         void set_text(bool b) { m_text = b; }
 
-        virtual bool is_readable() const { return true; }
-        virtual bool is_writable() const { return true; }
-        virtual bool is_executable() const { return true; }
+        bool is_readable() const { return m_readable; }
+        bool is_writable() const { return m_writable; }
+        bool is_executable() const { return m_executable; }
+
+        void set_readable(bool b) { m_readable = b; }
+        void set_writable(bool b) { m_writable = b; }
+        void set_executable(bool b) { m_executable = b; }
 
         virtual u8* data() = 0;
         virtual u8* shadow_data() = 0;
@@ -89,6 +93,9 @@ public:
 
         bool m_stack { false };
         bool m_text { false };
+        bool m_readable { true };
+        bool m_writable { true };
+        bool m_executable { true };
     };
 
     ValueWithShadow<u8> read8(X86::LogicalAddress);