RJIT: Optimize Kernel#block_given?

lib/ruby_vm/rjit/assembler.rb

@@ -243,6 +243,20 @@ module RubyVM::RJIT
       end
     end
 
+    def cmovne(dst, src)
+      case [dst, src]
+      # CMOVNE r64, r/m64 (Mod 11: reg)
+      in [R64 => dst_reg, R64 => src_reg]
+        # REX.W + 0F 45 /r
+        # RM: Operand 1: ModRM:reg (r, w), Operand 2: ModRM:r/m (r)
+        insn(
+          prefix: REX_W,
+          opcode: [0x0f, 0x45],
+          mod_rm: ModRM[mod: Mod11, reg: dst_reg, rm: src_reg],
+        )
+      end
+    end
+
     def cmovnz(dst, src)
       case [dst, src]
       # CMOVNZ r64, r/m64 (Mod 11: reg)

lib/ruby_vm/rjit/insn_compiler.rb

@@ -3033,6 +3033,29 @@ module RubyVM::RJIT
       true
     end
 
+    # @param jit [RubyVM::RJIT::JITState]
+    # @param ctx [RubyVM::RJIT::Context]
+    # @param asm [RubyVM::RJIT::Assembler]
+    def jit_rb_f_block_given_p(jit, ctx, asm, argc, _known_recv_class)
+      asm.comment('block_given?')
+
+      # Same as rb_vm_frame_block_handler
+      jit_get_lep(jit, asm, reg: :rax)
+      asm.mov(:rax, [:rax, C.VALUE.size * C::VM_ENV_DATA_INDEX_SPECVAL]) # block_handler
+
+      ctx.stack_pop(1)
+      out_opnd = ctx.stack_push
+
+      # Return `block_handler != VM_BLOCK_HANDLER_NONE`
+      asm.cmp(:rax, C::VM_BLOCK_HANDLER_NONE)
+      asm.mov(:rax, Qfalse)
+      asm.mov(:rcx, Qtrue)
+      asm.cmovne(:rax, :rcx) # block_given
+      asm.mov(out_opnd, :rax)
+
+      true
+    end
+
     # @param jit [RubyVM::RJIT::JITState]
     # @param ctx [RubyVM::RJIT::Context]
     # @param asm [RubyVM::RJIT::Assembler]
@@ -3089,7 +3112,7 @@ module RubyVM::RJIT
       register_cfunc_method(Array, :empty?, :jit_rb_ary_empty_p)
 
       register_cfunc_method(Kernel, :respond_to?, :jit_obj_respond_to)
-      #register_cfunc_method(Kernel, :block_given?, :jit_rb_f_block_given_p)
+      register_cfunc_method(Kernel, :block_given?, :jit_rb_f_block_given_p)
 
       # Thread.current
       register_cfunc_method(C.rb_singleton_class(Thread), :current, :jit_thread_s_current)

test/ruby/rjit/test_assembler.rb

@@ -93,6 +93,14 @@ module RubyVM::RJIT
       EOS
     end
 
+    def test_cmovne
+      asm = Assembler.new
+      asm.cmovne(:rax, :rbx) # CMOVNE r64, r/m64 (Mod 11: reg)
+      assert_compile(asm, <<~EOS) # cmovne == cmovnz
+        0x0: cmovne rax, rbx
+      EOS
+    end
+
     def test_cmovnz
       asm = Assembler.new
       asm.cmovnz(:rax, :rbx) # CMOVNZ r64, r/m64 (Mod 11: reg)