adds tracing functionality

src/iss/arch/riscv_hart_m_p.h

@@ -304,9 +304,9 @@ protected:
          */
         const std::string core_type_name() const override { return traits<BASE>::core_type; }
 
-        uint64_t get_pc() override { return arch.reg.PC; };
+        uint64_t get_pc() override { return arch.reg.PC; }
 
-        uint64_t get_next_pc() override { return arch.reg.NEXT_PC; };
+        uint64_t get_next_pc() override { return arch.reg.NEXT_PC; }
 
         uint64_t get_instr_word() override { return arch.reg.instruction; }
 
@@ -316,9 +316,11 @@ protected:
 
         uint64_t get_total_cycles() override { return arch.reg.icount + arch.cycle_offset; }
 
-        void update_last_instr_cycles(unsigned cycles) override { arch.cycle_offset += cycles - 1; };
+        void update_last_instr_cycles(unsigned cycles) override { arch.cycle_offset += cycles - 1; }
 
-        bool is_branch_taken() override { return arch.reg.last_branch; };
+        bool is_branch_taken() override { return arch.reg.last_branch; }
+
+        unsigned get_reg_num() override {return traits<BASE>::NUM_REGS;}
 
         riscv_hart_m_p<BASE, FEAT> &arch;
     };

src/iss/arch/riscv_hart_msu_vp.h

@@ -331,9 +331,9 @@ protected:
          */
         const std::string core_type_name() const override { return traits<BASE>::core_type; }
 
-        uint64_t get_pc() override { return arch.reg.PC; };
+        uint64_t get_pc() override { return arch.reg.PC; }
 
-        uint64_t get_next_pc() override { return arch.reg.NEXT_PC; };
+        uint64_t get_next_pc() override { return arch.reg.NEXT_PC; }
 
         uint64_t get_instr_word() override { return arch.reg.instruction; }
 
@@ -343,9 +343,11 @@ protected:
 
         uint64_t get_total_cycles() override { return arch.reg.icount + arch.cycle_offset; }
 
-        void update_last_instr_cycles(unsigned cycles) override { arch.cycle_offset += cycles - 1; };
+        void update_last_instr_cycles(unsigned cycles) override { arch.cycle_offset += cycles - 1; }
 
-        bool is_branch_taken() override { return arch.reg.last_branch; };
+        bool is_branch_taken() override { return arch.reg.last_branch; }
+
+        unsigned get_reg_num() override {return traits<BASE>::NUM_REGS; }
 
         riscv_hart_msu_vp<BASE> &arch;
     };

src/iss/arch/riscv_hart_mu_p.h

@@ -329,9 +329,9 @@ protected:
          */
         const std::string core_type_name() const override { return traits<BASE>::core_type; }
 
-        uint64_t get_pc() override { return arch.reg.PC; };
+        uint64_t get_pc() override { return arch.reg.PC; }
 
-        uint64_t get_next_pc() override { return arch.reg.NEXT_PC; };
+        uint64_t get_next_pc() override { return arch.reg.NEXT_PC; }
 
         uint64_t get_instr_word() override { return arch.reg.instruction; }
 
@@ -341,9 +341,11 @@ protected:
 
         uint64_t get_total_cycles() override { return arch.reg.icount + arch.cycle_offset; }
 
-        void update_last_instr_cycles(unsigned cycles) override { arch.cycle_offset += cycles - 1; };
+        void update_last_instr_cycles(unsigned cycles) override { arch.cycle_offset += cycles - 1; }
 
-        bool is_branch_taken() override { return arch.reg.last_branch; };
+        bool is_branch_taken() override { return arch.reg.last_branch; }
+
+        unsigned get_reg_num() override {return traits<BASE>::NUM_REGS; }
 
         riscv_hart_mu_p<BASE, FEAT> &arch;
     };

src/iss/plugin/README.md

@@ -0,0 +1,8 @@
+# pctrace
+
+Trace functionality to allow visualizing coverage in lcov and cachegrind tools. Use environment variables NOCOMPRES and REGDUMP to toggle functionality.
+- NOCOMPRES: any value turns off the LZ4 compression
+- REGDUMP: any value switches to tracing the registers instead. Also turns off compression.
+
+Known Bugs: 
+- currently does not work correctly with jit backends, the plugin cant tell if instructions are compressed. Additionaly the cost of instrs that raise a trap is not known. It takes the cost of the instrid -1 (0 at the moment).

src/iss/plugin/pctrace.cpp

@@ -29,7 +29,7 @@
  * POSSIBILITY OF SUCH DAMAGE.
  *
  * Contributors:
- *       alex.com - initial implementation
+ *       alex@minres.com - initial implementation
  ******************************************************************************/
 
 #include <iss/arch_if.h>
@@ -55,11 +55,11 @@ using namespace rapidjson;
 using namespace std;
 
 #ifdef WITH_LZ4
-class lz4compress_steambuf: public std::streambuf {
+class lz4compress_streambuf: public std::streambuf {
 public:
-    lz4compress_steambuf(const lz4compress_steambuf&) = delete;
-    lz4compress_steambuf& operator=(const lz4compress_steambuf&) = delete;
-    lz4compress_steambuf(std::ostream &sink, size_t buf_size)
+    lz4compress_streambuf(const lz4compress_streambuf&) = delete;
+    lz4compress_streambuf& operator=(const lz4compress_streambuf&) = delete;
+    lz4compress_streambuf(std::ostream &sink, size_t buf_size)
     : sink(sink)
     , src_buf(buf_size)
     , dest_buf(LZ4F_compressBound(buf_size, nullptr))
@@ -74,7 +74,7 @@ public:
         sink.write(dest_buf.data(), ret);
     }
 
-    ~lz4compress_steambuf() {
+    ~lz4compress_streambuf() {
         close();
     }
 
@@ -126,17 +126,21 @@ private:
 pctrace::pctrace(std::string const &filename)
 : instr_if(nullptr)
 , filename(filename)
+, reg_dump(getenv("REGDUMP"))
+, no_compres(getenv("NOCOMPRES"))
 , output("output.trc")
 #ifdef WITH_LZ4
-, strbuf(new lz4compress_steambuf(output, 4096))
+, strbuf( (no_compres || reg_dump)? nullptr: new lz4compress_streambuf(output, 4096))
 , ostr(strbuf.get())
 #endif
-{ }
+{}
 
 pctrace::~pctrace() { }
 
 bool pctrace::registration(const char *const version, vm_if& vm) {
     instr_if = vm.get_arch()->get_instrumentation_if();
+    reg_base_ptr = reinterpret_cast<uint32_t*>(vm.get_arch()->get_regs_base_ptr());
+
     if(!instr_if) return false;
     const string  core_name = instr_if->core_type_name();
     if (filename.length() > 0) {
@@ -203,12 +207,22 @@ void pctrace::callback(instr_info_t iinfo) {
         if (entry.not_taken > 1)
             instr_if->update_last_instr_cycles(entry.not_taken);
     }
-#ifndef WITH_LZ4
-    output<<std::hex <<"0x" << instr_if->get_pc() <<"," << delay <<"," << call<<","<<(compressed?2:4) <<"\n";
-#else
-    auto rdbuf=ostr.rdbuf();
+    if(no_compres|| reg_dump){
+        if(reg_dump){
+            for(size_t i=0; i< instr_if->get_reg_num(); ++i){
+                uint32_t reg_val = *(reg_base_ptr+i);
+                output << "0x" << std::setfill('0') << std::setw(8) << std::hex << reg_val << " ";
+            }
+            output<<"\n" ;
+        }
+        else{
+             output<<std::hex <<"0x" << instr_if->get_pc() <<"," << delay <<"," << call<<","<<(compressed?2:4) <<std::endl;
+        }
+        
+    }else{
+        
         ostr<<std::hex <<"0x" << instr_if->get_pc() <<"," << delay <<"," << call<<","<<(compressed?2:4) <<"\n";
-#endif
-}
-}
+    }
 }
+}//namespace plugin
+}//namespace iss

src/iss/plugin/pctrace.h

@@ -39,11 +39,10 @@
 #include "iss/instrumentation_if.h"
 #include <string>
 #include <fstream>
-
-
+#include <cstdlib>
 namespace iss {
 namespace plugin {
-class lz4compress_steambuf;
+class lz4compress_streambuf;
 class pctrace : public iss::vm_plugin {
     struct instr_delay {
         std::string instr_name;
@@ -86,9 +85,13 @@ public:
 
 private:
     iss::instrumentation_if *instr_if  {nullptr};
+    uint32_t* reg_base_ptr {nullptr};
+    bool reg_dump {false};
+    bool no_compres {false};   
     std::ofstream output;
+
 #ifdef WITH_LZ4
-    std::unique_ptr<lz4compress_steambuf> strbuf;
+    std::unique_ptr<lz4compress_streambuf> strbuf;
     std::ostream ostr;
 #endif
     std::string filename;