From b0053072fa93f2e8738150ad69c61c89bfad8f53 Mon Sep 17 00:00:00 2001
From: inglorion <voodoo@inglorion.net>
Date: Sat, 3 Nov 2012 20:24:49 -0700
Subject: [PATCH] Implement auto-bytes and auto-words for ARM

---
 lib/voodoo/generators/arm_gas_generator.rb | 57 ++++++++++++++++++++++++++----
 1 file changed, 50 insertions(+), 7 deletions(-)

diff --git a/lib/voodoo/generators/arm_gas_generator.rb b/lib/voodoo/generators/arm_gas_generator.rb
index bdbceab..2ff7537 100644
--- a/lib/voodoo/generators/arm_gas_generator.rb
+++ b/lib/voodoo/generators/arm_gas_generator.rb
@@ -60,11 +60,14 @@ module Voodoo
   #
   class ARMGasGenerator < CommonCodeGenerator
     def initialize params
-      @WORDSIZE = 4
+      @WORDSIZE_BITS = 2
+      @WORDSIZE = 1 << @WORDSIZE_BITS
       @CODE_ALIGNMENT = 4
       @DATA_ALIGNMENT = @WORDSIZE
       @FUNCTION_ALIGNMENT = @WORDSIZE
-
+      @STACK_ALIGNMENT_BITS = 3
+      @STACK_ALIGNMENT = 1 << @STACK_ALIGNMENT_BITS
+      
       @INITIAL_FRAME_SIZE = 2 * @WORDSIZE
       @NREGISTER_ARGS = 4
       @NREGISTER_LOCALS = 6
@@ -145,6 +148,39 @@ module Voodoo
       value.respond_to?(:[]) && value[0] == :'@'
     end
 
+    def auto_bytes value, register
+      if value.kind_of? Integer
+	grow_frame value
+      else
+	temporary = register == :sp ? @TEMPORARY : register
+        load_value_into_register value, temporary
+	auto_bytes_register temporary
+      end
+      emit "cpy #{register}, sp\n" unless register == :sp
+    end
+    
+    # auto-bytes where the value is supplied in a register and the return
+    # value will be in sp. register must not be sp.
+    def auto_bytes_register register
+      temporary = register == @TEMPORARY ? :r3 : @TEMPORARY
+      emit "add #{register}, #{register}, \##{@STACK_ALIGNMENT - 1}\n"
+      emit "mvn #{temporary}, \##{@STACK_ALIGNMENT - 1}\n"
+      emit "and #{register}, #{register}, #{temporary}\n"
+      emit "sub sp, #{temp1}\n"
+    end
+    
+    def auto_words value, register
+      if value.kind_of? Integer
+	auto_bytes(value * @WORDSIZE, register)
+      else
+	temporary = register == :sp ? @TEMPORARY : register
+	load_value_into_register value, temporary
+	emit "lsl #{temporary}, #{temporary}, \##{@WORDSIZE_BITS}\n"
+	auto_bytes_register temporary
+	emit "cpy #{register}, sp\n" unless register == :sp
+      end
+    end
+    
     # Begins a new block.
     def begin_block *code
       emit "# begin block\n"
@@ -247,10 +283,7 @@ module Voodoo
 
       # Calculate frame size so that the stack pointer will
       # be properly aligned at the end of emit_function_prologue.
-      @frame_size = (clobbered.length + nstack_vars) * @WORDSIZE
-      if @frame_size % 8 != 0
-        @frame_size = (@frame_size + 7) / 8 * 8
-      end
+      @frame_size = stack_align((clobbered.length + nstack_vars) * @WORDSIZE)
       extra_space = @frame_size - clobbered.length * @WORDSIZE
       if extra_space > 0
         emit "sub sp, sp, \##{extra_space}\n"
@@ -437,6 +470,10 @@ module Voodoo
         # Evaluate expression
         op = expr[0]
         case op
+	when :'auto-bytes'
+	  auto_bytes expr[1], register
+	when :'auto-words'
+	  auto_words expr[1], register
         when :call
           call *expr[1..-1]
           emit "cpy #{register}, #{@RETURN}\n" if register != @RETURN
@@ -524,7 +561,7 @@ module Voodoo
     # Grows the current frame by n words, plus padding to
     # respect alignment rules.
     def grow_frame nwords
-      increment = (nwords * @WORDSIZE + 7) / 8 * 8
+      increment = stack_align(nwords * @WORDSIZE)
       emit "sub sp, sp, \##{increment}\n"
       @frame_size = @frame_size + increment
       @frame_offset = @frame_offset + increment
@@ -787,6 +824,12 @@ module Voodoo
       end
     end
 
+    # Given n, returns the nearest multiple of @STACK_ALIGNMENT
+    # that is >= n.
+    def stack_align n
+      (n + @STACK_ALIGNMENT - 1) / @STACK_ALIGNMENT * @STACK_ALIGNMENT
+    end
+    
     # Define a string with the given value
     def string value
       code = ''
-- 
2.11.4.GIT