[PATCH 2/2] rs6000: Refine integer comparison handlings in rs6000_emit_vector_compare

["Kewen.Lin" <linkw@linux.ibm.com>]

Hi,

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.  This patch is
to refine the handlings for vector integer comparison operators,
it becomes not recursive, and we don't need the helper function
rs6000_emit_vector_compare_inner any more.

Bootstrapped and regtested on powerpc64-linux-gnu P7 and P8,
and powerpc64le-linux-gnu P9 and P10.

I'm going to push this later this week if no objections.

BR,
Kewen
-----
gcc/ChangeLog:

	* config/rs6000/rs6000.cc (rs6000_emit_vector_compare_inner): Remove.
	(rs6000_emit_vector_compare): Refine it by directly using the reversed
	or swapped code, to avoid the recursion.
---
 gcc/config/rs6000/rs6000.cc | 159 ++++++++----------------------------
 1 file changed, 34 insertions(+), 125 deletions(-)

diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 56db12f08a0..21f4cda7b80 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -15639,169 +15639,78 @@ output_cbranch (rtx op, const char *label, int reversed, rtx_insn *insn)
   return string;
 }

-/* Return insn for VSX or Altivec comparisons.  */
-
-static rtx
-rs6000_emit_vector_compare_inner (enum rtx_code code, rtx op0, rtx op1)
-{
-  rtx mask;
-  machine_mode mode = GET_MODE (op0);
-
-  switch (code)
-    {
-    default:
-      break;
-
-    case GE:
-      if (GET_MODE_CLASS (mode) == MODE_VECTOR_INT)
-	return NULL_RTX;
-      /* FALLTHRU */
-
-    case EQ:
-    case GT:
-    case GTU:
-      mask = gen_reg_rtx (mode);
-      emit_insn (gen_rtx_SET (mask, gen_rtx_fmt_ee (code, mode, op0, op1)));
-      return mask;
-    }
-
-  return NULL_RTX;
-}
-
 /* 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,
 			    rtx op0, rtx op1,
 			    machine_mode dmode)
 {
-  rtx mask;
   gcc_assert (VECTOR_UNIT_ALTIVEC_OR_VSX_P (dmode));
   gcc_assert (GET_MODE (op0) == GET_MODE (op1));
+  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
      just emit the comparison rtx insn directly here.  Besides,
      we should have a centralized place to handle the possibility
-     of raising invalid exception.  */
-  if (GET_MODE_CLASS (dmode) == MODE_VECTOR_FLOAT)
+     of raising invalid exception.  Also emit directly for vector
+     integer comparison operators EQ/GT/GTU.  */
+  if (GET_MODE_CLASS (dmode) == MODE_VECTOR_FLOAT
+      || 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;
     }

   bool swap_operands = false;
-  bool try_again = false;
-
-  /* See if the comparison works as is.  */
-  mask = rs6000_emit_vector_compare_inner (rcode, op0, op1);
-  if (mask)
-    return mask;
+  bool need_invert = false;
+  enum rtx_code code = UNKNOWN;

   switch (rcode)
     {
     case LT:
-      rcode = GT;
-      swap_operands = true;
-      try_again = true;
-      break;
     case LTU:
-      rcode = GTU;
+      code = swap_condition (rcode);
       swap_operands = true;
-      try_again = true;
       break;
     case NE:
-      /* Invert condition and try again.
-	 e.g., A != B becomes ~(A==B).  */
-      {
-	enum rtx_code rev_code;
-	enum insn_code nor_code;
-	rtx mask2;
-
-	rev_code = reverse_condition_maybe_unordered (rcode);
-	if (rev_code == UNKNOWN)
-	  return NULL_RTX;
-
-	nor_code = optab_handler (one_cmpl_optab, dmode);
-	if (nor_code == CODE_FOR_nothing)
-	  return NULL_RTX;
-
-	mask2 = rs6000_emit_vector_compare (rev_code, op0, op1, dmode);
-	if (!mask2)
-	  return NULL_RTX;
-
-	mask = gen_reg_rtx (dmode);
-	emit_insn (GEN_FCN (nor_code) (mask, mask2));
-	return mask;
-      }
+    case LE:
+    case LEU:
+      code = reverse_condition (rcode);
+      need_invert = true;
       break;
     case GE:
+      code = GT;
+      swap_operands = true;
+      need_invert = true;
+      break;
     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;
-      }
+      code = GTU;
+      swap_operands = true;
+      need_invert = true;
       break;
     default:
-      return NULL_RTX;
+      gcc_unreachable ();
+      break;
     }

-  if (try_again)
-    {
-      if (swap_operands)
-	std::swap (op0, op1);
+  if (swap_operands)
+    std::swap (op0, op1);
+
+  emit_insn (gen_rtx_SET (mask, gen_rtx_fmt_ee (code, dmode, op0, op1)));

-      mask = rs6000_emit_vector_compare_inner (rcode, op0, op1);
-      if (mask)
-	return mask;
+  if (need_invert)
+    {
+      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));
     }

-  /* You only get two chances.  */
-  return NULL_RTX;
+  return mask;
 }

 /* Emit vector conditional expression.  DEST is destination. OP_TRUE and
--
2.27.0