Remove PC argument from ujit instructions

gen_ujit_examples.rb

@@ -1,5 +1,5 @@
 def get_example_instruction_id
-  # TODO we could get this from the script that generates vm.inc instead of dothings this song and dance
+  # TODO we could get this from the script that generates vm.inc instead of doing this song and dance
   `dwarfdump --name='YARVINSN_ujit_call_example' vm.o`.each_line do |line|
     if (id = line[/DW_AT_const_value\s\((\d+\))/, 1])
       p [__method__, line] if $DEBUG
@@ -108,4 +108,3 @@ p offset_to_insn_in_tc_table if $DEBUG
 offset_to_handler_code_from_vm_exec_core = readint8b(offset_to_insn_in_tc_table)
 p offset_to_handler_code_from_vm_exec_core if $DEBUG
 disassemble(vm_exec_core_offset + offset_to_handler_code_from_vm_exec_core)
-

iseq.c

@@ -3465,7 +3465,7 @@ trace_set_i(void *vstart, void *vend, size_t stride, void *data)
 }
 
 VALUE *
-rb_ujit_empty_func(rb_control_frame_t *cfp, const VALUE *pc)
+rb_ujit_empty_func(rb_control_frame_t *cfp)
 {
     // okay, not really empty, so maybe think of another name.
     // it's put in this file instead of say, compile.c to dodge long C compile time.

iseq.h

@@ -313,7 +313,7 @@ VALUE rb_iseq_defined_string(enum defined_type type);
 /* vm.c */
 VALUE rb_iseq_local_variables(const rb_iseq_t *iseq);
 
-NOINLINE(VALUE *rb_ujit_empty_func(rb_control_frame_t *cfp, const VALUE *pc));
+NOINLINE(VALUE *rb_ujit_empty_func(rb_control_frame_t *cfp));
 
 
 RUBY_SYMBOL_EXPORT_END

tool/ruby_vm/views/vm.inc.erb

@@ -34,7 +34,7 @@ INSN_ENTRY(<%= insn.name %>)
     START_OF_ORIGINAL_INSN(<%= insn.name %>);
     // assumes USE_MACHINE_REGS, aka reg_pc setup,
     // aka #define SET_PC(x) (reg_cfp->pc = reg_pc = (x))
-    reg_pc = rb_ujit_empty_func(GET_CFP(), reg_pc);
+    reg_pc = rb_ujit_empty_func(GET_CFP());
     END_INSN(<%= insn.name %>);
 }
 % end

ujit_asm.c

@@ -97,6 +97,17 @@ x86opnd_t imm_opnd(int64_t imm)
     return opnd;
 }
 
+x86opnd_t const_ptr_opnd(void* ptr)
+{
+    x86opnd_t opnd = {
+        OPND_IMM,
+        64,
+        .unsig_imm = (uint64_t)ptr
+    };
+
+    return opnd;
+}
+
 void cb_init(codeblock_t* cb, size_t mem_size)
 {
     // Map the memory as executable

ujit_asm.h

@@ -127,7 +127,7 @@ typedef struct X86Opnd
         int64_t imm;
 
         // Unsigned immediate value
-        uint64_t unsigImm;
+        uint64_t unsig_imm;
     };
 
 } x86opnd_t;
@@ -177,6 +177,9 @@ x86opnd_t mem_opnd(size_t num_bits, x86opnd_t base_reg, int32_t disp);
 // Immediate number operand
 x86opnd_t imm_opnd(int64_t val);
 
+// Constant pointer operand
+x86opnd_t const_ptr_opnd(void* ptr);
+
 void cb_init(codeblock_t* cb, size_t mem_size);
 void cb_set_pos(codeblock_t* cb, size_t pos);
 uint8_t* cb_get_ptr(codeblock_t* cb, size_t index);

ujit_compile.c

@@ -63,9 +63,13 @@ ujit_compile_insn(rb_iseq_t *iseq, size_t insn_idx)
     }
 
     int insn = (int)iseq->body->iseq_encoded[insn_idx];
+	int len = insn_len(insn);
     //const char* name = insn_name(insn);
     //printf("%s\n", name);
 
+    // Compute the address of the next instruction
+    void* next_pc = &iseq->body->iseq_encoded[insn_idx + len];
+
     // Get a pointer to the current write position in the code block
     uint8_t* code_ptr = &cb->mem_block[cb->write_pos];
     //printf("write pos: %ld\n", cb->write_pos);
@@ -80,9 +84,12 @@ ujit_compile_insn(rb_iseq_t *iseq, size_t insn_idx)
         // Write the pre call bytes
         ujit_instr_entry(cb);
 
-        add(cb, RSI, imm_opnd(8));                  // increment PC
+        //add(cb, RSI, imm_opnd(8));                  // increment PC
-        mov(cb, mem_opnd(64, RDI, 0), RSI);         // write new PC to EC object, not necessary for nop bytecode?
+        //mov(cb, mem_opnd(64, RDI, 0), RSI);         // write new PC to EC object, not necessary for nop bytecode?
-        mov(cb, RAX, RSI);                          // return new PC
+        //mov(cb, RAX, RSI);                          // return new PC
+
+        // Directly return the next PC, which is a constant
+        mov(cb, RAX, const_ptr_opnd(next_pc));
 
         // Write the post call bytes
         ujit_instr_exit(cb);
@@ -98,9 +105,9 @@ ujit_compile_insn(rb_iseq_t *iseq, size_t insn_idx)
         ujit_instr_entry(cb);
 
         sub(cb, mem_opnd(64, RDI, 8), imm_opnd(8)); // decrement SP
-        add(cb, RSI, imm_opnd(8));                  // increment PC
+
-        mov(cb, mem_opnd(64, RDI, 0), RSI);         // write new PC to EC object, not necessary for pop bytecode?
+        // Directly return the next PC, which is a constant
-        mov(cb, RAX, RSI);                          // return new PC
+        mov(cb, RAX, const_ptr_opnd(next_pc));
 
         // Write the post call bytes
         ujit_instr_exit(cb);