[PATCH 1/3] find_a_program: First search with machine prefix

[John Ericson <git@JohnEricson.me>]

This matches the behavior of Clang, and makes it easier to work with
cross compilers without heeding to hard-code paths at build time.
---
 gcc/gcc.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 68 insertions(+), 10 deletions(-)

diff --git a/gcc/gcc.c b/gcc/gcc.c
index 1a74bf92f7a..710cbfe9a66 100644
--- a/gcc/gcc.c
+++ b/gcc/gcc.c
@@ -1582,6 +1582,11 @@ static const char *machine_suffix = 0;
 
 static const char *just_machine_suffix = 0;
 
+/* Prefix to attach to *basename* of commands being searched.
+   This is just `MACHINE-'.  */
+
+static const char *just_machine_prefix = 0;
+
 /* Adjusted value of GCC_EXEC_PREFIX envvar.  */
 
 static const char *gcc_exec_prefix;
@@ -3026,15 +3031,6 @@ file_at_path (char *path, void *data)
   memcpy (path + len, info->name, info->name_len);
   len += info->name_len;
 
-  /* Some systems have a suffix for executable files.
-     So try appending that first.  */
-  if (info->suffix_len)
-    {
-      memcpy (path + len, info->suffix, info->suffix_len + 1);
-      if (access_check (path, info->mode) == 0)
-	return path;
-    }
-
   path[len] = '\0';
   if (access_check (path, info->mode) == 0)
     return path;
@@ -3074,12 +3070,52 @@ find_a_file (const struct path_prefix *pprefix, const char *name, int mode,
 				file_at_path, &info);
 }
 
+/* Callback for find_a_program.  Appends the file name to the directory
+   path. Like file_at_path but tries machine prefix and exe suffix too. */
+
+static void *
+program_at_path (char *path, void *data)
+{
+  /* try first with machine-prefixed name */
+  struct file_at_path_info *info = (struct file_at_path_info *) data;
+  size_t path_len = strlen (path);
+
+  for (auto prefix : { just_machine_prefix, "" })
+    {
+      auto len = path_len;
+
+      auto prefix_len = strlen(prefix);
+      memcpy (path + len, prefix, prefix_len);
+      len += prefix_len;
+
+      memcpy (path + len, info->name, info->name_len);
+      len += info->name_len;
+
+      /* Some systems have a suffix for executable files.
+	 So try appending that first.  */
+      if (info->suffix_len)
+	{
+	  memcpy (path + len, info->suffix, info->suffix_len + 1);
+	  if (access_check (path, info->mode) == 0)
+	    return path;
+	}
+
+      path[len] = '\0';
+      if (access_check (path, info->mode) == 0)
+	return path;
+    }
+
+  return NULL;
+}
+
 /* Specialization of find_a_file for programs that also takes into account
    configure-specified default programs. */
 
 static char*
 find_a_program (const char *name)
 {
+  const int mode = X_OK;
+
   /* Do not search if default matches query. */
 
 #ifdef DEFAULT_ASSEMBLER
@@ -3097,7 +3133,28 @@ find_a_program (const char *name)
     return xstrdup (DEFAULT_DSYMUTIL);
 #endif
 
-  return find_a_file (&exec_prefixes, name, X_OK, false);
+  /* Find the filename in question (special case for absolute paths).  */
+
+  if (IS_ABSOLUTE_PATH (name))
+    {
+      if (access (name, mode) == 0)
+	return xstrdup (name);
+
+      return NULL;
+    }
+
+  struct file_at_path_info info;
+
+  info.name = name;
+  info.suffix = HOST_EXECUTABLE_SUFFIX;
+  info.name_len = strlen (info.name);
+  info.suffix_len = strlen (info.suffix);
+  info.mode = mode;
+
+  return (char*) for_each_path (
+    &exec_prefixes, false,
+    info.name_len + info.suffix_len + strlen(just_machine_prefix),
+    program_at_path, &info);
 }
 
 /* Ranking of prefixes in the sort list. -B prefixes are put before
@@ -8328,6 +8385,7 @@ driver::set_up_specs () const
   machine_suffix = concat (spec_host_machine, dir_separator_str, spec_version,
 			   accel_dir_suffix, dir_separator_str, NULL);
   just_machine_suffix = concat (spec_machine, dir_separator_str, NULL);
+  just_machine_prefix = concat (spec_machine, "-", NULL);
 
   specs_file = find_a_file (&startfile_prefixes, "specs", R_OK, true);
   /* Read the specs file unless it is a default one.  */
-- 
2.31.1