From ca0fbe891d0f8278b4824d6b2c5db4cd01fcef5c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Magnus=20L=C3=A5ng?= <margnus1@telia.com>
Date: Wed, 9 Nov 2016 18:46:19 +0100
Subject: 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').
---
 lib/hipe/ppc/hipe_rtl_to_ppc.erl | 89 +++++++++++++++++++++-------------------
 1 file changed, 47 insertions(+), 42 deletions(-)

(limited to 'lib/hipe/ppc/hipe_rtl_to_ppc.erl')

diff --git a/lib/hipe/ppc/hipe_rtl_to_ppc.erl b/lib/hipe/ppc/hipe_rtl_to_ppc.erl
index a01e67a789..09f1ce5a49 100644
--- a/lib/hipe/ppc/hipe_rtl_to_ppc.erl
+++ b/lib/hipe/ppc/hipe_rtl_to_ppc.erl
@@ -80,7 +80,6 @@ conv_insn(I, Map, Data) ->
   case I of
     #alu{} -> conv_alu(I, Map, Data);
     #alub{} -> conv_alub(I, Map, Data);
-    #branch{} -> conv_branch(I, Map, Data);
     #call{} -> conv_call(I, Map, Data);
     #comment{} -> conv_comment(I, Map, Data);
     #enter{} -> conv_enter(I, Map, Data);
@@ -441,36 +440,53 @@ mk_alu_rr(Dst, Src1, RtlAluOp, Src2) ->
 
 conv_alub(I, Map, Data) ->
   %% dst = src1 aluop src2; if COND goto label
-  {Dst, Map0} = conv_dst(hipe_rtl:alub_dst(I), Map),
-  {Src1, Map1} = conv_src(hipe_rtl:alub_src1(I), Map0),
-  {Src2, Map2} = conv_src(hipe_rtl:alub_src2(I), Map1),
-  {AluOp, BCond} =
-    case {hipe_rtl:alub_op(I), hipe_rtl:alub_cond(I)} of
-      {'add', 'ltu'} ->
-	{'addc', 'eq'};
-      {RtlAlubOp, RtlAlubCond} ->
-	{conv_alub_op(RtlAlubOp), conv_alub_cond(RtlAlubCond)}
-    end,
-  BC = mk_pseudo_bc(BCond,
-		    hipe_rtl:alub_true_label(I),
-		    hipe_rtl:alub_false_label(I),
-		    hipe_rtl:alub_pred(I)),
-  I2 =
-    case {AluOp, BCond} of
-      {'addc', 'eq'} ->	% copy XER[CA] to CR0[EQ] before the BC
-	TmpR = new_untagged_temp(),
-	[hipe_ppc:mk_mfspr(TmpR, 'xer'),
-	 hipe_ppc:mk_mtcr(TmpR) |
-	 BC];
-      _ -> BC
-    end,
-  {NewSrc1, NewSrc2} =
-    case AluOp of
-      'subf' -> {Src2, Src1};
-      _ -> {Src1, Src2}
-    end,
-  I1 = mk_alub(Dst, NewSrc1, AluOp, NewSrc2, BCond),
-  {I1 ++ I2, Map2, Data}.
+  HasDst = hipe_rtl:alub_has_dst(I),
+  {Src1, Map0} = conv_src(hipe_rtl:alub_src1(I), Map),
+  {Src2, Map1} = conv_src(hipe_rtl:alub_src2(I), Map0),
+  RtlAlubOp = hipe_rtl:alub_op(I),
+  RtlAlubCond = hipe_rtl:alub_cond(I),
+  case {HasDst, RtlAlubOp} of
+    {false, sub} ->
+      {BCond,Sign} = conv_branch_cond(RtlAlubCond),
+      I2 = mk_branch(Src1, BCond, Sign, Src2,
+		     hipe_rtl:alub_true_label(I),
+		     hipe_rtl:alub_false_label(I),
+		     hipe_rtl:alub_pred(I)),
+      {I2, Map1, Data};
+    _ ->
+      {Dst, Map2} =
+	case HasDst of
+	  false -> {new_untagged_temp(), Map1};
+	  true -> conv_dst(hipe_rtl:alub_dst(I), Map1)
+	end,
+      {AluOp, BCond} =
+	case {RtlAlubOp, RtlAlubCond} of
+	  {'add', 'ltu'} ->
+	    {'addc', 'eq'};
+	  {_, _} ->
+	    {conv_alub_op(RtlAlubOp), conv_alub_cond(RtlAlubCond)}
+	end,
+      BC = mk_pseudo_bc(BCond,
+			hipe_rtl:alub_true_label(I),
+			hipe_rtl:alub_false_label(I),
+			hipe_rtl:alub_pred(I)),
+      I2 =
+	case {AluOp, BCond} of
+	  {'addc', 'eq'} ->	% copy XER[CA] to CR0[EQ] before the BC
+	    TmpR = new_untagged_temp(),
+	    [hipe_ppc:mk_mfspr(TmpR, 'xer'),
+	     hipe_ppc:mk_mtcr(TmpR) |
+	     BC];
+	  _ -> BC
+	end,
+      {NewSrc1, NewSrc2} =
+	case AluOp of
+	  'subf' -> {Src2, Src1};
+	  _ -> {Src1, Src2}
+	end,
+      I1 = mk_alub(Dst, NewSrc1, AluOp, NewSrc2, BCond),
+      {I1 ++ I2, Map2, Data}
+  end.
 
 conv_alub_op(RtlAluOp) ->
   case {get(hipe_target_arch), RtlAluOp} of
@@ -689,17 +705,6 @@ mk_alub_rr_Rc(Dst, Src1, AluOp, Src2) ->
     end,
   [hipe_ppc:mk_alu(AluOpDot, Dst, Src1, Src2)].
 
-conv_branch(I, Map, Data) ->
-  %% <unused> = src1 - src2; if COND goto label
-  {Src1, Map0} = conv_src(hipe_rtl:branch_src1(I), Map),
-  {Src2, Map1} = conv_src(hipe_rtl:branch_src2(I), Map0),
-  {BCond,Sign} = conv_branch_cond(hipe_rtl:branch_cond(I)),
-  I2 = mk_branch(Src1, BCond, Sign, Src2,
-		 hipe_rtl:branch_true_label(I),
-		 hipe_rtl:branch_false_label(I),
-		 hipe_rtl:branch_pred(I)),
-  {I2, Map1, Data}.
-
 conv_branch_cond(Cond) -> % may be unsigned
   case Cond of
     gtu -> {'gt', 'unsigned'};
-- 
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