[PATCH, i386]: Tighten inline_secondary_memory_needed to reject moves between (SSE,mask) and non-general regs

[Uros Bizjak]

2019-08-29  Uroš Bizjak  <ubiz...@gmail.com>

    * config/i386/i386.c (inline_secondary_memory_needed): Return true
    for moves between SSE and non-general registers and between
    mask and non-general registers.
    (ix86_register_move_cost): Remove stalled comment.

Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.

Committed to mainline SVN.

Uros.

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index d2d84eb11663..1c9c719f22a3 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -18306,32 +18306,36 @@ inline_secondary_memory_needed (machine_mode mode, 
reg_class_t class1,
   if (FLOAT_CLASS_P (class1) != FLOAT_CLASS_P (class2))
     return true;
 
-  /* Between mask and general, we have moves no larger than word size.  */
-  if ((MASK_CLASS_P (class1) != MASK_CLASS_P (class2))
-      && (GET_MODE_SIZE (mode) > UNITS_PER_WORD))
-  return true;
-
   /* ??? This is a lie.  We do have moves between mmx/general, and for
      mmx/sse2.  But by saying we need secondary memory we discourage the
      register allocator from using the mmx registers unless needed.  */
   if (MMX_CLASS_P (class1) != MMX_CLASS_P (class2))
     return true;
 
+  /* Between mask and general, we have moves no larger than word size.  */
+  if (MASK_CLASS_P (class1) != MASK_CLASS_P (class2))
+    {
+      if (!(INTEGER_CLASS_P (class1) || INTEGER_CLASS_P (class2))
+         || GET_MODE_SIZE (mode) > UNITS_PER_WORD)
+       return true;
+    }
+
   if (SSE_CLASS_P (class1) != SSE_CLASS_P (class2))
     {
       /* SSE1 doesn't have any direct moves from other classes.  */
       if (!TARGET_SSE2)
        return true;
 
+      /* Between SSE and general, we have moves no larger than word size.  */
+      if (!(INTEGER_CLASS_P (class1) || INTEGER_CLASS_P (class2))
+         || GET_MODE_SIZE (mode) > UNITS_PER_WORD)
+       return true;
+
       /* If the target says that inter-unit moves are more expensive
         than moving through memory, then don't generate them.  */
       if ((SSE_CLASS_P (class1) && !TARGET_INTER_UNIT_MOVES_FROM_VEC)
          || (SSE_CLASS_P (class2) && !TARGET_INTER_UNIT_MOVES_TO_VEC))
        return true;
-
-      /* Between SSE and general, we have moves no larger than word size.  */
-      if (GET_MODE_SIZE (mode) > UNITS_PER_WORD)
-       return true;
     }
 
   return false;
@@ -18608,15 +18612,7 @@ ix86_register_move_cost (machine_mode mode, 
reg_class_t class1_i,
   if (MMX_CLASS_P (class1) != MMX_CLASS_P (class2))
     gcc_unreachable ();
 
-  /* Moves between SSE and integer units are expensive.  */
   if (SSE_CLASS_P (class1) != SSE_CLASS_P (class2))
-
-    /* ??? By keeping returned value relatively high, we limit the number
-       of moves between integer and SSE registers for all targets.
-       Additionally, high value prevents problem with x86_modes_tieable_p(),
-       where integer modes in SSE registers are not tieable
-       because of missing QImode and HImode moves to, from or between
-       MMX/SSE registers.  */
     return (SSE_CLASS_P (class1)
            ? ix86_cost->hard_register.sse_to_integer
            : ix86_cost->hard_register.integer_to_sse);