Add new cond-rw pass to have forward propagation track cond branches

Add a new pass to rewrite conditional branches.  This is introducing
and placing a new LIMPLE operator 'assume' in use by fwprop to
propagate conditional branch test informations on target basic blocks.

	* lisp/emacs-lisp/comp.el (comp-passes): Add `comp-cond-rw'.
	(comp-limple-assignments): Add `assume' operator.
	(comp-emit-assume, comp-cond-rw-target-slot, comp-cond-rw-func)
	(comp-cond-rw): Add new functions.
	(comp-fwprop-insn): Update to pattern match `assume' insns.
	* src/comp.c (emit_limple_insn): Add for `assume'.
	(syms_of_comp): Define 'Qassume' symbol.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/comp.c b/src/comp.c
index 0c555578f81..48e4f1c8cde 100644
--- a/src/comp.c
+++ b/src/comp.c
@@ -2131,9 +2131,9 @@ emit_limple_insn (Lisp_Object insn)
                                n);
       emit_cond_jump (test, target2, target1);
     }
-  else if (EQ (op, Qphi))
+  else if (EQ (op, Qphi) || EQ (op, Qassume))
     {
-      /* Nothing to do for phis into the backend.  */
+      /* Nothing to do for phis or assumes in the backend.  */
     }
   else if (EQ (op, Qpush_handler))
     {
@@ -5134,6 +5134,7 @@ native compiled one.  */);
   DEFSYM (Qcallref, "callref");
   DEFSYM (Qdirect_call, "direct-call");
   DEFSYM (Qdirect_callref, "direct-callref");
+  DEFSYM (Qassume, "assume");
   DEFSYM (Qsetimm, "setimm");
   DEFSYM (Qreturn, "return");
   DEFSYM (Qcomp_mvar, "comp-mvar");