mds-kbdc: prepare for dead code elimination

Signed-off-by: Mattias Andrée <maandree@operamail.com>

3 files changed, 262 insertions, 1 deletions

diff --git a/src/mds-kbdc/eliminate-dead-code.c b/src/mds-kbdc/eliminate-dead-code.c
new file mode 100644
index 0000000..495cbb5
--- /dev/null
+++ b/src/mds-kbdc/eliminate-dead-code.c
@@ -0,0 +1,224 @@
+/**
+ * mds — A micro-display server
+ * Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "eliminate-dead-code.h"
+
+#include <stdlib.h>
+#include <errno.h>
+
+
+
+/**
+ * Tree type constant shortener
+ */
+#define C(TYPE)  MDS_KBDC_TREE_TYPE_##TYPE
+
+/**
+ * Add an error to the error list
+ * 
+ * @param  NODE:const mds_kbdc_tree_t*    The node the triggered the error
+ * @param  SEVERITY:identifier            * in `MDS_KBDC_PARSE_ERROR_*` to indicate severity
+ * @param  ...:const char*, ...           Error description format string and arguments
+ * @scope  error:mds_kbdc_parse_error_t*  Variable where the new error will be stored
+ */
+#define NEW_ERROR(NODE, SEVERITY, ...)					\
+  NEW_ERROR_(result, SEVERITY, 1, (NODE)->loc_line,			\
+	     (NODE)->loc_start, (NODE)->loc_end, 1, __VA_ARGS__)
+
+/**
+ * Add “included from here”-notes
+ * 
+ * @param  PTR:size_t  The number of “included from here”-notes
+ */
+#define DUMP_INCLUDE_STACK(PTR)		\
+  fail_if (dump_include_stack(PTR))
+
+/**
+ * Add an error with “included from here”-notes to the error list
+ * 
+ * @param  NODE:const mds_kbdc_tree_t*    The node the triggered the error
+ * @param  PTR:size_t                     The number of “included from here”-notes
+ * @param  SEVERITY:identifier            * in `MDS_KBDC_PARSE_ERROR_*` to indicate severity
+ * @param  ...:const char*, ...           Error description format string and arguments
+ * @scope  error:mds_kbdc_parse_error_t*  Variable where the new error will be stored
+ */
+#define NEW_ERROR_WITH_INCLUDES(NODE, PTR, SEVERITY, ...)	\
+  do								\
+    {								\
+      NEW_ERROR(NODE, SEVERITY, __VA_ARGS__);			\
+      DUMP_INCLUDE_STACK(PTR);					\
+    }								\
+  while (0)
+
+
+
+/**
+ * Variable whether the latest created error is stored
+ */
+static mds_kbdc_parse_error_t* error;
+
+/**
+ * The parameter of `eliminate_dead_code`
+ */
+static mds_kbdc_parsed_t* restrict result;
+
+/**
+ * The original value of `result->pathname`
+ */
+static char* original_pathname;
+
+/**
+ * The original value of `result->source_code`
+ */
+static mds_kbdc_source_code_t* original_source_code;
+
+/**
+ * Stack of visited include-statements
+ */
+static mds_kbdc_tree_include_t** restrict includes = NULL;
+
+/**
+ * The number elements allocated for `includes`
+ */
+static size_t includes_size = 0;
+
+/**
+ * The number elements stored in `includes`
+ */
+static size_t includes_ptr = 0;
+
+
+
+/**
+ * Validate that a part of the structure of the compilation unit
+ * 
+ * @param   tree  The tree to validate
+ * @return        Zero on success, -1 on error
+ */
+static int eliminate_subtree(mds_kbdc_tree_t* restrict tree);
+
+
+
+/**
+ * Add “included from here”-notes
+ * 
+ * @param   ptr  The number of “included from here”-notes
+ * @return       Zero on success, -1 on error
+ */
+static int dump_include_stack(size_t ptr)
+{
+  char* old_pathname = result->pathname;
+  mds_kbdc_source_code_t* old_source_code = result->source_code;
+  while (ptr--)
+    {
+      result->pathname = ptr ? includes[ptr - 1]->filename : original_pathname;
+      result->source_code = ptr ? includes[ptr - 1]->source_code : original_source_code;
+      NEW_ERROR(includes[ptr], NOTE, "included from here");
+    }
+  result->pathname = old_pathname;
+  result->source_code = old_source_code;
+  return 0;
+ pfail:
+  result->pathname = old_pathname;
+  result->source_code = old_source_code;
+  return -1;
+} 
+
+  
+/**
+ * Eliminate dead code in an include-statement
+ * 
+ * @param   tree  The tree to reduce
+ * @return        Zero on success, -1 on error
+ */
+static int eliminate_include(mds_kbdc_tree_include_t* restrict tree)
+{
+  mds_kbdc_tree_include_t** old;
+  char* pathname = result->pathname;
+  mds_kbdc_source_code_t* source_code = result->source_code;
+  int r, saved_errno;
+  if (includes_ptr == includes_size)
+    if (xxrealloc(old, includes, includes_size += 4, mds_kbdc_tree_include_t*))
+      return saved_errno = errno, free(old), errno = saved_errno, -1;
+  includes[includes_ptr++] = tree;
+  result->pathname = tree->filename;
+  result->source_code = tree->source_code;
+  r = eliminate_subtree(tree->inner);
+  result->pathname = pathname;
+  result->source_code = source_code;
+  return includes_ptr--, r;
+}
+
+
+/**
+ * Eliminate dead code in a subtree
+ * 
+ * @param   tree  The tree to reduce
+ * @return        Zero on success, -1 on error
+ */
+static int eliminate_subtree(mds_kbdc_tree_t* restrict tree)
+{
+#define e(type)  if ((r = eliminate_##type(&(tree->type))))     return r
+#define E(type)  if ((r = eliminate_##type(&(tree->type##_))))  return r
+  int r;
+ again:
+  if (tree == NULL)
+    return 0;
+  
+  switch (tree->type)
+    {
+    case C(INCLUDE):  e(include);  break;
+    default:
+      break;
+    }
+  
+  tree = tree->next;
+  goto again;
+#undef E
+#undef e
+}
+
+
+/**
+ * Eliminate and warn about dead code
+ * 
+ * @param   result_  `result` from `validate_tree`, will be updated
+ * @return            -1 if an error occursed that cannot be stored in `result`, zero otherwise
+ */
+int eliminate_dead_code(mds_kbdc_parsed_t* restrict result_)
+{
+  int r, saved_errno;
+  result = result_;
+  original_pathname = result_->pathname;
+  original_source_code = result_->source_code;
+  r = eliminate_subtree(result_->tree);
+  saved_errno = errno;
+  result_->pathname = original_pathname;
+  result_->source_code = original_source_code;
+  free(includes), includes = NULL;
+  includes_size = includes_ptr = 0;
+  return errno = saved_errno, r;
+}
+
+
+
+#undef NEW_ERROR_WITH_INCLUDES
+#undef DUMP_INCLUDE_STACK
+#undef NEW_ERROR
+#undef C
+
+ 
diff --git a/src/mds-kbdc/eliminate-dead-code.h b/src/mds-kbdc/eliminate-dead-code.h
new file mode 100644
index 0000000..55c351a
--- /dev/null
+++ b/src/mds-kbdc/eliminate-dead-code.h
@@ -0,0 +1,35 @@
+/**
+ * mds — A micro-display server
+ * Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef MDS_MDS_KBDC_ELIMINATE_DEAD_CODE_H
+#define MDS_MDS_KBDC_ELIMINATE_DEAD_CODE_H
+
+
+#include "parsed.h"
+
+
+/**
+ * Eliminate and warn about dead code
+ * 
+ * @param   result  `result` from `validate_tree`, will be updated
+ * @return          -1 if an error occursed that cannot be stored in `result`, zero otherwise
+ */
+int eliminate_dead_code(mds_kbdc_parsed_t* restrict result);
+
+
+#endif
+
diff --git a/src/mds-kbdc/mds-kbdc.c b/src/mds-kbdc/mds-kbdc.c
index 9c668c8..6f4be18 100644
--- a/src/mds-kbdc/mds-kbdc.c
+++ b/src/mds-kbdc/mds-kbdc.c
@@ -21,6 +21,8 @@
 #include "make-tree.h"
 #include "simplify-tree.h"
 #include "process-includes.h"
+#include "validate-tree.h"
+#include "eliminate-dead-code.h"
 
 #include <libmdsserver/macros.h>
 
@@ -56,7 +58,7 @@ int main(int argc_, char** argv_)
   process (simplify_tree(&result));
   process (process_includes(&result));
   process (validate_tree(&result));
-  /* TODO process (eliminate_dead_code(&result)); */
+  process (eliminate_dead_code(&result));
   /* TODO process (compile_layout(&result)); */
   /* TODO process (assemble_layout(&result)); */
  stop: