rs6000: Rework vector integer comparison in rs6000_emit_vector_compare - p4

The current handlings in rs6000_emit_vector_compare is a bit
complicated to me, especially after we emit vector float
comparison insn with the given code directly.  So it's better
to refactor the handlings of vector integer comparison here.

This is part 4, it's to rework the handlings on GE/GEU/LE/LEU,
also make the function not recursive any more.  This patch
doesn't introduce any functionality change.

gcc/ChangeLog:

	* config/rs6000/rs6000.cc (rs6000_emit_vector_compare): Refine the
	handlings for operators GE/GEU/LE/LEU.

gcc/config/rs6000/rs6000.cc

@@ -16010,7 +16010,7 @@ output_cbranch (rtx op, const char *label, int reversed, rtx_insn *insn)
 }
 /* Emit vector compare for operands OP0 and OP1 using code RCODE.
-   DMODE is expected destination mode. This is a recursive function.  */
+   DMODE is expected destination mode.  */
 static rtx
 rs6000_emit_vector_compare (enum rtx_code rcode,
@@ -16019,7 +16019,7 @@ rs6000_emit_vector_compare (enum rtx_code rcode,
 {
   gcc_assert (VECTOR_UNIT_ALTIVEC_OR_VSX_P (dmode));
   gcc_assert (GET_MODE (op0) == GET_MODE (op1));
-  rtx mask;
+  rtx mask = gen_reg_rtx (dmode);
   /* In vector.md, we support all kinds of vector float point
      comparison operators in a comparison rtl pattern, we can
@@ -16028,7 +16028,6 @@ rs6000_emit_vector_compare (enum rtx_code rcode,
      of raising invalid exception.  */
   if (GET_MODE_CLASS (dmode) == MODE_VECTOR_FLOAT)
     {
-      mask = gen_reg_rtx (dmode);
       emit_insn (gen_rtx_SET (mask, gen_rtx_fmt_ee (rcode, dmode, op0, op1)));
       return mask;
     }
@@ -16037,11 +16036,7 @@ rs6000_emit_vector_compare (enum rtx_code rcode,
      have direct hardware instructions, just emit it directly
      here.  */
   if (rcode == EQ || rcode == GT || rcode == GTU)
-    {
-      mask = gen_reg_rtx (dmode);
-      emit_insn (gen_rtx_SET (mask, gen_rtx_fmt_ee (rcode, dmode, op0, op1)));
-      return mask;
-    }
+    emit_insn (gen_rtx_SET (mask, gen_rtx_fmt_ee (rcode, dmode, op0, op1)));
   else if (rcode == LT || rcode == LTU)
     {
       /* lt{,u}(a,b) = gt{,u}(b,a)  */
@@ -16049,76 +16044,28 @@ rs6000_emit_vector_compare (enum rtx_code rcode,
       std::swap (op0, op1);
       mask = gen_reg_rtx (dmode);
       emit_insn (gen_rtx_SET (mask, gen_rtx_fmt_ee (code, dmode, op0, op1)));
-      return mask;
     }
-  else if (rcode == NE)
+  else if (rcode == NE || rcode == LE || rcode == LEU)
     {
-      /* ne(a,b) = ~eq(a,b)  */
+      /* ne(a,b) = ~eq(a,b); le{,u}(a,b) = ~gt{,u}(a,b)  */
+      enum rtx_code code = reverse_condition (rcode);
       mask = gen_reg_rtx (dmode);
-      emit_insn (gen_rtx_SET (mask, gen_rtx_fmt_ee (EQ, dmode, op0, op1)));
+      emit_insn (gen_rtx_SET (mask, gen_rtx_fmt_ee (code, dmode, op0, op1)));
+      enum insn_code nor_code = optab_handler (one_cmpl_optab, dmode);
+      gcc_assert (nor_code != CODE_FOR_nothing);
+      emit_insn (GEN_FCN (nor_code) (mask, mask));
+    } else {
+      /* ge{,u}(a,b) = ~gt{,u}(b,a)  */
+      gcc_assert (rcode == GE || rcode == GEU);
+      enum rtx_code code = rcode == GE ? GT : GTU;
+      mask = gen_reg_rtx (dmode);
+      emit_insn (gen_rtx_SET (mask, gen_rtx_fmt_ee (code, dmode, op0, op1)));
       enum insn_code nor_code = optab_handler (one_cmpl_optab, dmode);
       gcc_assert (nor_code != CODE_FOR_nothing);
       emit_insn (GEN_FCN (nor_code) (mask, mask));
-      return mask;
-    }
-
-  switch (rcode)
-    {
-    case GE:
-    case GEU:
-    case LE:
-    case LEU:
-      /* Try GT/GTU/LT/LTU OR EQ */
-      {
-	rtx c_rtx, eq_rtx;
-	enum insn_code ior_code;
-	enum rtx_code new_code;
-
-	switch (rcode)
-	  {
-	  case  GE:
-	    new_code = GT;
-	    break;
-
-	  case GEU:
-	    new_code = GTU;
-	    break;
-
-	  case LE:
-	    new_code = LT;
-	    break;
-
-	  case LEU:
-	    new_code = LTU;
-	    break;
-
-	  default:
-	    gcc_unreachable ();
-	  }
-
-	ior_code = optab_handler (ior_optab, dmode);
-	if (ior_code == CODE_FOR_nothing)
-	  return NULL_RTX;
-
-	c_rtx = rs6000_emit_vector_compare (new_code, op0, op1, dmode);
-	if (!c_rtx)
-	  return NULL_RTX;
-
-	eq_rtx = rs6000_emit_vector_compare (EQ, op0, op1, dmode);
-	if (!eq_rtx)
-	  return NULL_RTX;
-
-	mask = gen_reg_rtx (dmode);
-	emit_insn (GEN_FCN (ior_code) (mask, c_rtx, eq_rtx));
-	return mask;
-      }
-      break;
-    default:
-      return NULL_RTX;
     }
-  /* You only get two chances.  */
-  return NULL_RTX;
+  return mask;
 }
 /* Emit vector conditional expression.  DEST is destination. OP_TRUE and