hipe_rtl: unify branch and alub

branch and alub overlap in their use cases, but the backends rely on
knowing that the result is unused in their lowering of branch. By
extending alub so that the destination is optional, it can fully replace
branch.

This simplifies rtl by reducing code duplication and the number of
instructions.

Also, in the x86 and arm backends, we can now use 'test' and
{'tst','mvn','teq'} to lower some alubs without destinations. This is
particularly good for x86, as sequences such as 'is_boxed' type tests
now get shorter (both from not needing a mov to copy the variable, but
also from the fact that 'testb' encodes shorter than 'andq').

1 files changed, 12 insertions, 70 deletions

diff --git a/lib/hipe/rtl/hipe_rtl_ssa_const_prop.erl b/lib/hipe/rtl/hipe_rtl_ssa_const_prop.erl
index 7158383010..f887eeab66 100644
--- a/lib/hipe/rtl/hipe_rtl_ssa_const_prop.erl
+++ b/lib/hipe/rtl/hipe_rtl_ssa_const_prop.erl
@@ -110,8 +110,6 @@ visit_expression(Instruction, Environment) ->
       visit_alu(Instruction, Environment);
     #alub{} ->
       visit_alub(Instruction, Environment);
-    #branch{} ->
-      visit_branch(Instruction, Environment);
     #call{} ->
       visit_call(Instruction, Environment);
 %%    #comment{} ->
@@ -184,42 +182,6 @@ set_to(Dst, Val, Env) ->
   {[], SSAWork, Env1}.
 
 %%-----------------------------------------------------------------------------
-%% Procedure : visit_branch/2
-%% Purpose   : do symbolic exection of branch instructions.
-%% Arguments : Inst - The instruction
-%%             Env  - The environment
-%% Returns   : { FlowWorkList, SSAWorkList, NewEnvironment}
-%%-----------------------------------------------------------------------------
-
-visit_branch(Inst, Env) -> %% Titta också på exekverbarflagga
-  Val1 = lookup_lattice_value(hipe_rtl:branch_src1(Inst), Env),
-  Val2 = lookup_lattice_value(hipe_rtl:branch_src2(Inst), Env),
-  CFGWL = case evaluate_relop(Val1, hipe_rtl:branch_cond(Inst), Val2) of
-            true   -> [hipe_rtl:branch_true_label(Inst)];
-            false  -> [hipe_rtl:branch_false_label(Inst)];
-            bottom -> [hipe_rtl:branch_true_label(Inst), 
-	               hipe_rtl:branch_false_label(Inst)];
-            top    -> []
-          end,
-  {CFGWL, [], Env}.
-
-%%-----------------------------------------------------------------------------
-%% Procedure : evaluate_relop/3
-%% Purpose   : evaluate the given relop. While taking care to handle top & 
-%%             bottom in some sane way.
-%% Arguments : Val1, Val2 - The operands Integers or top or bottom
-%%             RelOp  - some relop atom from rtl. 
-%% Returns   : bottom, top, true or false
-%%-----------------------------------------------------------------------------
-
-evaluate_relop(Val1, RelOp, Val2) ->
-  if 
-    (Val1==bottom) or (Val2==bottom) -> bottom ;
-    (Val1==top) or (Val2==top)       ->  top;
-    true ->  hipe_rtl_arch:eval_cond(RelOp, Val1, Val2)
-  end.
-
-%%-----------------------------------------------------------------------------
 %% Procedure : evaluate_fixnumop/2 
 %% Purpose   : try to evaluate a fixnumop.
 %% Arguments : Val1 - operand (an integer, 'top' or 'bottom')
@@ -408,6 +370,7 @@ partial_eval_branch(Cond, N0, Z0, V0, C0) ->
        Cond =:= 'ne'           -> {true, Z0,   true, true};
        Cond =:= 'gt';
        Cond =:= 'le'           -> {N0,   Z0,   V0,   true};
+       Cond =:= 'leu';
        Cond =:= 'gtu'          -> {true, Z0,   true, C0  };
        Cond =:= 'lt';
        Cond =:= 'ge'           -> {N0,   true, V0,   true};
@@ -450,7 +413,11 @@ visit_alub(Inst, Env) ->
           false  -> [hipe_rtl:alub_false_label(Inst)]
         end
      end,
-  {[], NewSSA, NewEnv} = set_to(hipe_rtl:alub_dst(Inst), NewVal,  Env),
+  {[], NewSSA, NewEnv} =
+    case hipe_rtl:alub_has_dst(Inst) of
+      false -> {[], [], Env};
+      true -> set_to(hipe_rtl:alub_dst(Inst), NewVal, Env)
+    end,
   {Labels, NewSSA, NewEnv}.
       
 %%-----------------------------------------------------------------------------
@@ -688,8 +655,6 @@ update_instruction(Inst, Env) ->
       update_alu(Inst, Env);
     #alub{} ->
       update_alub(Inst, Env);
-    #branch{} ->
-      update_branch(Inst, Env);
     #call{} ->
       subst_all_uses(Inst, Env);
 %%    #comment{} ->
@@ -902,33 +867,6 @@ update_alu(Inst, Env) ->
       {Val,_,_,_,_} = evaluate_alu(Val1, hipe_rtl:alu_op(Inst), Val2),
       [hipe_rtl:mk_move(hipe_rtl:alu_dst(Inst), hipe_rtl:mk_imm(Val))]
   end.
- 
-%%-----------------------------------------------------------------------------
-%% Procedure : update_branch/2
-%% Purpose   : update an branch-instruction
-%% Arguments : Inst - the instruction.
-%%             Env - in which everything happens.
-%% Returns   : list of new instruction
-%%-----------------------------------------------------------------------------
-
-update_branch(Inst, Env) ->
-  Src1 = hipe_rtl:branch_src1(Inst),
-  Src2 = hipe_rtl:branch_src2(Inst),
-  Val1 = lookup_lattice_value(Src1, Env),
-  Val2 = lookup_lattice_value(Src2, Env),
-  if
-    (Val1 =:= bottom) and (Val2 =:= bottom) ->
-      [Inst];
-    Val1 =:= bottom ->
-      [hipe_rtl:subst_uses([{Src2, hipe_rtl:mk_imm(Val2)}], Inst)];
-    Val2 =:= bottom -> 
-      [hipe_rtl:subst_uses([{Src1, hipe_rtl:mk_imm(Val1)}], Inst)];
-    true ->
-      case hipe_rtl_arch:eval_cond(hipe_rtl:branch_cond(Inst), Val1, Val2) of
-        true  -> [hipe_rtl:mk_goto(hipe_rtl:branch_true_label(Inst))];
-        false -> [hipe_rtl:mk_goto(hipe_rtl:branch_false_label(Inst))]
-      end
-  end.
 
 %%-----------------------------------------------------------------------------
 %% Procedure : update_alub/2
@@ -943,8 +881,12 @@ update_branch(Inst, Env) ->
 
 %% some small helpers.
 alub_to_move(Inst, Res, Lab) ->
-  [hipe_rtl:mk_move(hipe_rtl:alub_dst(Inst), Res),
-   hipe_rtl:mk_goto(Lab)].
+  Goto = [hipe_rtl:mk_goto(Lab)],
+  case hipe_rtl:alub_has_dst(Inst) of
+    false -> Goto;
+    true ->
+      [hipe_rtl:mk_move(hipe_rtl:alub_dst(Inst), Res) | Goto]
+  end.
 
 make_alub_subst_list(bottom, _, Tail) ->  Tail;
 make_alub_subst_list(top, Src, _) ->