From cbb589740133d53224fcd66c4c2decf43a7eca6e Mon Sep 17 00:00:00 2001
From: Peter Wu <lekensteyn@gmail.com>
Date: Sat, 3 Dec 2011 13:55:31 +0000
Subject: Support multiple declarations in the global scope

---
 README       |  3 ++-
 Variables.py | 21 ++++++++++++++++++++-
 pp2cc.py     | 16 +++++++++++++---
 3 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/README b/README
index 29b6dff..6adfb4a 100644
--- a/README
+++ b/README
@@ -100,7 +100,8 @@ A8.7 Initialization - Supported for an expression resulting in an int, arrays
             may be initialized with a list of expressions yielding a constant
             value, e.g. int a[2]={3,1+2};int b[]={2}; in If the number of
             initializers are larger than the dimension, the excess elements are
-            discarded.
+            discarded. Multi-dimensional arrays are not supported at
+            initialization.
 
 A8.8 Type names - not verified
 A8.9 Typedef - won't be supported as we have int only
diff --git a/Variables.py b/Variables.py
index 617113f..89c8501 100644
--- a/Variables.py
+++ b/Variables.py
@@ -84,7 +84,10 @@ class GlobalVariables(Variables):
         defined in assembly
         """
         self.defined_names = defined_names
+        # key: variable name, value: name as it appears in assembly
         self.global_vars = {}
+        # a list of variable names which are declared and defined
+        self.global_vars_defined = []
     def _uniqName(self, name):
         """Returns an unique global variable name for assembly"""
         uniq_name = name
@@ -93,6 +96,12 @@ class GlobalVariables(Variables):
             uniq_name = name + "_" + str(i)
             i += 1
         return uniq_name
+    def isDeclared(self, name):
+        """Returns True if the global variable is declared, False otherwise"""
+        return name in self.global_vars
+    def isDefined(self, name):
+        """Returns True if the global variable is defined, False otherwise"""
+        return name in self.global_vars_defined
     def getAddress(self, name):
         """Gets the address for a variable as a tuple containing a register and
         displacement
@@ -100,7 +109,7 @@ class GlobalVariables(Variables):
         To get the address of the variable, add the register value and
         displacement
         """
-        if name in self.global_vars:
+        if self.isDeclared(name):
             return ("GB", self.global_vars[name])
         raise RuntimeError("Use of undefined variable '{}'".format(name))
     def declName(self, name, size=1, is_param=False, is_static=False):
@@ -138,3 +147,13 @@ class GlobalVariables(Variables):
         else:
             # insert size items, initialized with 0
             self.defined_names[var_name] = ["0"] * size
+    def defName(self, name):
+        """Marks a variable name as defined
+
+        Variables may be declared multiple times in the globa scope, but not
+        defined multiple times
+        """
+        assert self.isDeclared(name), "Definition of undeclared '{}'".format(name)
+        if self.isDefined(name):
+            raise RuntimeError("Redefinition of '{}'".format(name))
+        self.global_vars_defined.append(name)
diff --git a/pp2cc.py b/pp2cc.py
index 03a57a1..190f10a 100755
--- a/pp2cc.py
+++ b/pp2cc.py
@@ -988,7 +988,7 @@ class Parse(object):
             if not linked_type.node.type.names[0] in ("int", "void"):
                 self.logger.warning("Only void and int types are supported", linked_node)
         elif linked_type.type == "FuncDecl":
-            # a function declaration does not accept an initializaer, but it's
+            # a function declaration does not accept an initializer, but it's
             # still special because it has params
             return self.parseStatement(linked_type.node, linked_node)
         else:
@@ -1000,8 +1000,11 @@ class Parse(object):
         size += 1
 
         try:
-            is_static = "static" in linked_node.node.storage
-            linked_node.variables.declName(name, size, is_static=is_static)
+            # global variables may be declared multiple times, local variables
+            # are not allowed for that
+            if in_function or not linked_node.variables.isDeclared(name):
+                is_static = "static" in linked_node.node.storage
+                linked_node.variables.declName(name, size, is_static=is_static)
             # address of variable split up in register and displacement
             var_reg, var_disp = linked_node.variables.getAddress(name)
         except RuntimeError as errmsg:
@@ -1020,6 +1023,13 @@ class Parse(object):
                                                       var_reg + "+" + var_disp + "]"))
         # if the declaration also has a definition
         if linked_node.node.init:
+            # global variables needs to be marked as defined
+            if not in_function:
+                try:
+                    linked_node.variables.defName(name)
+                except RuntimeError as errmsg:
+                    self.logger.error(errmsg, linked_node=linked_node)
+
             init_vals = []
             linked_init = LinkedNode(linked_node.node.init, linked_node)
             if (linked_type.type == "ArrayDecl" and
-- 
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