From 51e451404c3a8a78180977ab0709c39a624b1eeb Mon Sep 17 00:00:00 2001
From: inglorion <voodoo@inglorion.net>
Date: Thu, 1 Oct 2009 10:23:17 +0200
Subject: [PATCH] More work on AMD64 code generator.

---
 lib/ruby/voodoo/generators/amd64_nasm_generator.rb | 148 +++++++++++++++++++++
 1 file changed, 148 insertions(+)

diff --git a/lib/ruby/voodoo/generators/amd64_nasm_generator.rb b/lib/ruby/voodoo/generators/amd64_nasm_generator.rb
index 97d6f54..7b32e79 100644
--- a/lib/ruby/voodoo/generators/amd64_nasm_generator.rb
+++ b/lib/ruby/voodoo/generators/amd64_nasm_generator.rb
@@ -40,6 +40,8 @@ module Voodoo
     def initialize params
       # Number of bytes in a word
       @WORDSIZE = 8
+      # Word name in NASM lingo
+      @WORD_NAME = 'qword'
       # Default alignment for code
       @CODE_ALIGNMENT = 0
       # Default alignment for data
@@ -52,6 +54,10 @@ module Voodoo
       @SCRATCH_REG = 'r11'
       # Registers used for argument passing
       @ARG_REGS = ['rdi', 'rsi', 'rdx', 'rcx', 'r8', 'r9']
+      # Base index
+      @BASE_INDEX = 'rbx'
+      # Count index
+      @COUNT_INDEX = 'rcx'
       super params
     end
 
@@ -127,6 +133,53 @@ module Voodoo
     # == Loading Values
     #
 
+    # Create a value reference to an address.
+    # Invoking this code may clobber @BASE_INDEX and/or @COUNT_INDEX
+    def load_address base, offset, scale
+      base_ref = load_value base, @BASE_INDEX
+      offset_ref = load_value offset, @COUNT_INDEX
+
+      if offset_ref == 0
+        if integer? base_ref
+          # Only an integer base
+          "[#{base_ref}]"
+        else
+          # Some complex base; load in @BASE_INDEX
+          emit "mov #{@BASE_INDEX}, #{base_ref}\n"
+          "[#{@BASE_INDEX}]"
+        end
+      elsif base_ref == 0
+        if integer? offset_ref
+          # Only a scaled offset
+          "[#{offset_ref.to_i * scale}]"
+        else
+          # Some complex offset; load in @COUNT_INDEX
+          emit "mov #{@COUNT_INDEX}, #{offset_ref}\n"
+          "[#{@COUNT_INDEX} * #{scale}]"
+        end
+      elsif integer? base_ref
+        if integer? offset_ref
+          # All integers, combine them together
+          "[#{base_ref.to_i + (offset_ref.to_i * scale)}]"
+        else
+          # Complex offset; use @COUNT_INDEX
+          emit "mov #{@COUNT_INDEX}, #{offset_ref}\n"
+          "[#{base_ref} + #{@COUNT_INDEX} * #{scale}]"
+        end
+      elsif integer? offset_ref
+        # Complex base, integer offset; use @BASE_INDEX
+        emit "mov #{@BASE_INDEX}, #{base_ref}\n"
+        "[#{@BASE_INDEX} + #{offset_ref.to_i * scale}]"
+      else
+        # Both base and offset are complex
+        # Use both @BASE_INDEX and @COUNT_INDEX
+        emit "mov #{@BASE_INDEX}, #{base_ref}\n"
+        emit "mov #{@COUNT_INDEX}, #{offset_ref}\n"
+        "[#{@BASE_INDEX} + #{@COUNT_INDEX} * #{scale}]"
+      end
+    end
+
+
     # Load the value of the nth argument
     def load_arg n, reg = @SCRATCH_REG
       if register_argument?(n)
@@ -150,6 +203,88 @@ module Voodoo
       "[rbp - #{offset + n * wordsize}]"
     end
 
+    # Load a value into a register
+    def load_value_into_register value, register
+      value_ref = load_value x, register
+      set_register register, value_ref
+    end
+
+    #
+    # == Expressions
+    #
+
+    # Perform division.
+    # The quotient is stored in @ACC_INDEX, the remainder in @DATA_INDEX.
+    def eval_div x, y
+      x_ref = load_value_into_register x, @ACC_INDEX
+      y_ref = load_value y, @SCRATCH_REG
+      set_register @DATA_INDEX, 0
+      emit "idiv #{@WORD_NAME} #{y_ref}\n"
+    end
+
+    # Evaluate an expression.
+    # The result is stored in _register_ (@RETURN_REG by default).
+    def eval_expr words, register = @RETURN_REG
+      if words.length == 1
+        if words[0] == 0
+          emit "xor #{register}, #{register}\n"
+        else
+          load_value words[0], register
+        end
+      else
+        op = words[0]
+        case op
+        when :call
+          call *words[1..-1]
+        when :div
+          eval_div words[1], words[2]
+          set_register register, @ACC_INDEX
+        when :'get-byte'
+          # Clear register
+          set_register register, 0
+          # Get address reference
+          address_ref = load_address words[1], words[2], 1
+          # Load byte from address
+          case register
+          when 'eax', 'rax'
+            set_register 'al', address_ref
+          when 'ebx', 'rbx'
+            set_register 'bl', address_ref
+          when 'ecx', 'rcx'
+            set_register 'cl', address_ref
+          when 'edx', 'rdx'
+            set_register 'dl', address_ref
+          else
+            set_register @BASE_INDEX, 0
+            set_register 'bl', address_ref
+            set_register register, @BASE_INDEX
+          end
+        when :'get-word'
+          address_ref = load_address words[1], words[2], @WORDSIZE
+          set_register register, address_ref
+        when :mod
+          eval_div words[1], words[2]
+          set_register register, @DATA_INDEX
+        when :mul
+          raise 'TODO'
+          eval_mul target_ref, words[1], words[2]
+        when :not
+          load_value_into_register words[1], register
+          emit "not #{register}\n"
+        else
+          raise 'TODO'
+          if binop?(op)
+            x_ref = load_value words[1], "edx"
+            y_ref = load_value words[2], "ebx"
+            emit "mov #{target_ref}, #{x_ref}\n"
+            emit "#{op} #{target_ref}, #{y_ref}\n"
+          else
+            raise "Not a magic word: #{words[0]}"
+          end
+        end
+      end
+    end
+
     #
     # == Miscellaneous
     #
@@ -182,6 +317,19 @@ module Voodoo
     def register_argument? n
       n < number_of_register_arguments
     end
+
+    # Set a register to a value.
+    # The value must be a valid operand to the mov instruction.
+    def set_register register, value_ref
+      case value_ref
+      when register
+        # Nothing to do
+      when 0
+        emit "xor #{register}, #{register}\n"
+      else
+        emit "mov #{register}, #{value_ref}\n"
+      end
+    end
   end
 
   # Register class
-- 
2.11.4.GIT