Optimize determine_rpath_dirs

When generating targets in ninja backend for my project,
`determine_rpath_dirs` is the second most expensive function
call. Here are some optimizations, mostly replacing expensive
regex with string manipulation.

mesonbuild/backend/backends.py

@@ -724,47 +724,56 @@ def get_external_rpath_dirs(self, target: build.BuildTarget) -> T.Set[str]:
         args: T.List[str] = []
         for lang in LANGUAGES_USING_LDFLAGS:
             try:
-                e = self.environment.coredata.get_external_link_args(target.for_machine, lang)
-                if isinstance(e, str):
-                    args.append(e)
-                else:
-                    args.extend(e)
-            except Exception:
+                args += self.environment.coredata.get_external_link_args(target.for_machine, lang)
+            except KeyError:
                 pass
         return self.get_rpath_dirs_from_link_args(args)
 
     @staticmethod
     def get_rpath_dirs_from_link_args(args: T.List[str]) -> T.Set[str]:
         dirs: T.Set[str] = set()
+
         # Match rpath formats:
         # -Wl,-rpath=
         # -Wl,-rpath,
-        rpath_regex = re.compile(r'-Wl,-rpath[=,]([^,]+)')
+
         # Match solaris style compat runpath formats:
         # -Wl,-R
         # -Wl,-R,
-        runpath_regex = re.compile(r'-Wl,-R[,]?([^,]+)')
+
         # Match symbols formats:
         # -Wl,--just-symbols=
         # -Wl,--just-symbols,
-        symbols_regex = re.compile(r'-Wl,--just-symbols[=,]([^,]+)')
+
         for arg in args:
-            rpath_match = rpath_regex.match(arg)
-            if rpath_match:
-                for dir in rpath_match.group(1).split(':'):
-                    dirs.add(dir)
-            runpath_match = runpath_regex.match(arg)
-            if runpath_match:
-                for dir in runpath_match.group(1).split(':'):
+            if not arg.startswith('-Wl,'):
+                continue
+
+            _wl, argname, *argparts = arg.split(',')
+            if argname.startswith('-R'):
+                if len(argname) > 2:
+                    argopt = argname[2:]
+                else:
+                    argopt = argparts[0]
+            elif '=' in argname:
+                argname, argopt = argname.split('=', maxsplit=1)
+            else:
+                argopt = argparts[0]
+
+            argopts = argopt.split(':')
+            if argname == '-rpath':
+                dirs.update(argopts)
+            elif argname == '-R':
+                for dir in argopts:
                     # The symbols arg is an rpath if the path is a directory
-                    if Path(dir).is_dir():
+                    if os.path.isdir(dir):
                         dirs.add(dir)
-            symbols_match = symbols_regex.match(arg)
-            if symbols_match:
-                for dir in symbols_match.group(1).split(':'):
+            elif argname == '--just-symbols':
+                for dir in argopts:
                     # Prevent usage of --just-symbols to specify rpath
-                    if Path(dir).is_dir():
+                    if os.path.isdir(dir):
                         raise MesonException(f'Invalid arg for --just-symbols, {dir} is a directory.')
+
         return dirs
 
     @lru_cache(maxsize=None)
@@ -779,7 +788,7 @@ def rpaths_for_non_system_absolute_shared_libraries(self, target: build.BuildTar
                 # For all link args that are absolute paths to a library file, add RPATH args
                 if not os.path.isabs(libpath):
                     continue
-                libdir = os.path.dirname(libpath)
+                libdir, libname = os.path.split(libpath)
                 if exclude_system and self._libdir_is_system(libdir, target.compilers, self.environment):
                     # No point in adding system paths.
                     continue
@@ -791,8 +800,8 @@ def rpaths_for_non_system_absolute_shared_libraries(self, target: build.BuildTar
                 # .dll is there for mingw gcc
                 # .so's may be extended with version information, e.g. libxyz.so.1.2.3
                 if not (
-                    os.path.splitext(libpath)[1] in {'.dll', '.lib', '.so', '.dylib'}
-                    or re.match(r'.+\.so(\.|$)', os.path.basename(libpath))
+                    libname.endswith(('.dll', '.lib', '.so', '.dylib'))
+                    or '.so.' in libname
                 ):
                     continue