glsl: Generate readable unique names at print time.

Since GLSL IR allows multiple ir_variables to share the same name, we
need to generate unique names when printing the IR.  Previously, we
always used %s@%p, appending the ir_variable's memory address.

While this worked, it had two drawbacks:
- When there aren't duplicates, the extra "@0x669a3e88" is useless
  and makes the code harder to read.
- Real duplicates were hard to tell apart:
  channel_expressions@0x6699e3c8 vs. channel_expressions@0x6699ddd8

We now append @2, @3, @4, and so on, but only where necessary to
distinguish duplicates.  Since we only do this at print time, any
performance impact is irrelevant.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Ian Romanick <idr@freedesktop.org>

src/glsl/ir_print_visitor.cpp

@@ -25,6 +25,10 @@
 #include "glsl_types.h"
 #include "glsl_parser_extras.h"
 
+extern "C" {
+#include "program/hash_table.h"
+}
+
 static void print_type(const glsl_type *t);
 
 void
@@ -67,6 +71,21 @@ _mesa_print_ir(exec_list *instructions,
    printf("\n)");
 }
 
+ir_print_visitor::ir_print_visitor()
+{
+   indentation = 0;
+   printable_names =
+      hash_table_ctor(32, hash_table_pointer_hash, hash_table_pointer_compare);
+   symbols = _mesa_symbol_table_ctor();
+   mem_ctx = ralloc_context(NULL);
+}
+
+ir_print_visitor::~ir_print_visitor()
+{
+   hash_table_dtor(printable_names);
+   _mesa_symbol_table_dtor(symbols);
+   ralloc_free(mem_ctx);
+}
 
 void ir_print_visitor::indent(void)
 {
@@ -74,6 +93,26 @@ void ir_print_visitor::indent(void)
       printf("  ");
 }
 
+const char *
+ir_print_visitor::unique_name(ir_variable *var)
+{
+   /* Do we already have a name for this variable? */
+   const char *name = (const char *) hash_table_find(this->printable_names, var);
+   if (name != NULL)
+      return name;
+
+   /* If there's no conflict, just use the original name */
+   if (_mesa_symbol_table_find_symbol(this->symbols, -1, var->name) == NULL) {
+      name = var->name;
+   } else {
+      static unsigned i = 1;
+      name = ralloc_asprintf(this->mem_ctx, "%s@%u", var->name, ++i);
+   }
+   hash_table_insert(this->printable_names, (void *) name, var);
+   _mesa_symbol_table_add_symbol(this->symbols, -1, name, var);
+   return name;
+}
+
 static void
 print_type(const glsl_type *t)
 {
@@ -104,12 +143,13 @@ void ir_print_visitor::visit(ir_variable *ir)
 	  cent, inv, mode[ir->mode], interp[ir->interpolation]);
 
    print_type(ir->type);
-   printf(" %s@%p)", ir->name, (void *) ir);
+   printf(" %s)", unique_name(ir));
 }
 
 
 void ir_print_visitor::visit(ir_function_signature *ir)
 {
+   _mesa_symbol_table_push_scope(symbols);
    printf("(signature ");
    indentation++;
 
@@ -148,6 +188,7 @@ void ir_print_visitor::visit(ir_function_signature *ir)
    indent();
    printf("))\n");
    indentation--;
+   _mesa_symbol_table_pop_scope(symbols);
 }
 
 
@@ -265,7 +306,7 @@ void ir_print_visitor::visit(ir_swizzle *ir)
 void ir_print_visitor::visit(ir_dereference_variable *ir)
 {
    ir_variable *var = ir->variable_referenced();
-   printf("(var_ref %s@%p) ", var->name, (void *) var);
+   printf("(var_ref %s) ", unique_name(var));
 }