Remove unused config option flexible_lifetime_start

slothy-optimizer · Jul 29, 2024 · 5b4c09a · 5b4c09a
1 parent d254f45
commit 5b4c09a
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Showing 2 changed files with 8 additions and 23 deletions.
diff --git a/slothy/core/config.py b/slothy/core/config.py
@@ -598,14 +598,6 @@ def split_heuristic_estimate_performance(self):
                 "read config.split_heuristic_estimate_performance otherwise.")
         return self._split_heuristic_estimate_performance
 
-    @property
-    def flexible_lifetime_start(self):
-        """Internal property indicating whether the lifetime interval of a register
-        should be allowed to extend _before_ the instructions which uses it."""
-        return \
-            self.constraints.maximize_register_lifetimes or \
-            (self.sw_pipelining.enabled and self.sw_pipelining.allow_post)
-
     @property
     def split_heuristic_repeat(self):
         """If split_heuristic is enabled, the number of times the splitting heuristic

diff --git a/slothy/core/core.py b/slothy/core/core.py
@@ -2210,16 +2210,12 @@ def make_start_var(name=""):
         for t in self._get_nodes(allnodes=True):
             # When we optimize for longest register lifetimes, we allow the starting time of the
             # usage interval to be smaller than the program order position of the instruction.
-            if self.config.flexible_lifetime_start:
-                t.out_lifetime_start = [
-                    make_start_var(f"{t.varname()}_out_{i}_lifetime_start")
-                        for i in range(t.inst.num_out) ]
-                t.inout_lifetime_start = [
-                    make_start_var(f"{t.varname()}_inout_{i}_lifetime_start")
-                        for i in range(t.inst.num_in_out) ]
-            else:
-                t.out_lifetime_start = [ t.program_start_var for _ in range(t.inst.num_out) ]
-                t.inout_lifetime_start = [ t.program_start_var for _ in range(t.inst.num_in_out) ]
+            t.out_lifetime_start = [
+                make_start_var(f"{t.varname()}_out_{i}_lifetime_start")
+                    for i in range(t.inst.num_out) ]
+            t.inout_lifetime_start = [
+                make_start_var(f"{t.varname()}_inout_{i}_lifetime_start")
+                    for i in range(t.inst.num_in_out) ]
 
             t.out_lifetime_end        = [ make_var(f"{t.varname()}_out_{i}_lifetime_end")
                                           for i in range(t.inst.num_out) ]
@@ -2474,11 +2470,8 @@ def _add_basic_constraints(start_list, end_list):
                 # Make sure the output argument is considered 'used' for at least
                 # one instruction. Otherwise, instructions producing outputs that
                 # are never used would be able to overwrite life registers.
-                self._Add( end_var > t.program_start_var )
-
-                # cf add_variables_dependencies()
-                if self.config.flexible_lifetime_start:
-                    self._Add(start_var <= t.program_start_var)
+                self._Add(end_var > t.program_start_var)
+                self._Add(start_var == t.program_start_var)
 
         _add_basic_constraints(t.out_lifetime_start, t.out_lifetime_end)
         _add_basic_constraints(t.inout_lifetime_start, t.inout_lifetime_end)