[PATCH] hppa64: Improve hppa_rtx_costs for DImode shifts by constants.

[Roger Sayle]

Hi Dave,
Here's another patch for you to try on hppa64.  I've no idea whether it
helps PR middle-end/87256 on hppa64 or makes things worse, but this
updates the DImode shift by constant costs on TARGET_64BIT, in the
same way that the previous rtx_costs patch improved the SImode costs.
Generating optimal code is a useful pre-requisite.  If nothing else, this
should reduce the number PA2.0 instructions generated for PR87256's
hog.c.

Please let me know what you think.


2020-09-07  Roger Sayle  <ro...@nextmovesoftware.com>

gcc/ChangeLog
        * config/pa/pa.c (hppa_rtx_costs) [ASHIFT, ASHIFTRT, LSHIFTRT]:
        Provide accurate costs for DImode shifts of integer constants.


Many thanks in advance,
Roger
--


diff --git a/gcc/config/pa/pa.c b/gcc/config/pa/pa.c
index a9223ab..210e44f 100644
--- a/gcc/config/pa/pa.c
+++ b/gcc/config/pa/pa.c
@@ -1630,13 +1630,16 @@ hppa_rtx_costs (rtx x, machine_mode mode, int 
outer_code,
     case ASHIFT:
       if (mode == DImode)
        {
-         if (TARGET_64BIT)
-           *total = COSTS_N_INSNS (3);
-         else if (REG_P (XEXP (x, 0)) && CONST_INT_P (XEXP (x, 1)))
+         if (REG_P (XEXP (x, 0)) && CONST_INT_P (XEXP (x, 1)))
            {
-             *total = COSTS_N_INSNS (2);
+             if (TARGET_64BIT)
+               *total = COSTS_N_INSNS (1);
+             else
+               *total = COSTS_N_INSNS (2);
              return true;
            }
+         else if (TARGET_64BIT)
+           *total = COSTS_N_INSNS (3);
          else if (speed)
            *total = COSTS_N_INSNS (13);
          else
@@ -1661,13 +1664,16 @@ hppa_rtx_costs (rtx x, machine_mode mode, int 
outer_code,
     case ASHIFTRT:
       if (mode == DImode)
        {
-         if (TARGET_64BIT)
-           *total = COSTS_N_INSNS (3);
-         else if (REG_P (XEXP (x, 0)) && CONST_INT_P (XEXP (x, 1)))
+         if (REG_P (XEXP (x, 0)) && CONST_INT_P (XEXP (x, 1)))
            {
-             *total = COSTS_N_INSNS (2);
+             if (TARGET_64BIT)
+               *total = COSTS_N_INSNS (1);
+             else
+               *total = COSTS_N_INSNS (2);
              return true;
            }
+         else if (TARGET_64BIT)
+           *total = COSTS_N_INSNS (3);
          else if (speed)
            *total = COSTS_N_INSNS (14);
          else
@@ -1692,13 +1698,16 @@ hppa_rtx_costs (rtx x, machine_mode mode, int 
outer_code,
     case LSHIFTRT:
       if (mode == DImode)
        {
-         if (TARGET_64BIT)
-           *total = COSTS_N_INSNS (2);
-         else if (REG_P (XEXP (x, 0)) && CONST_INT_P (XEXP (x, 1)))
+         if (REG_P (XEXP (x, 0)) && CONST_INT_P (XEXP (x, 1)))
            {
-             *total = COSTS_N_INSNS (2);
+             if (TARGET_64BIT)
+               *total = COSTS_N_INSNS (1);
+             else
+               *total = COSTS_N_INSNS (2);
              return true;
            }
+         else if (TARGET_64BIT)
+           *total = COSTS_N_INSNS (2);
          else if (speed)
            *total = COSTS_N_INSNS (12);
          else