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Blackfin patch: Correct set of registers valid for DImode


This is another old bug fix; we ran into a testcase where the compiler
came up with ALL_REGS as a valid class for holding a DImode value, and
tried to split it across registers M3 and A0.  While A0, being a 40 bit
accumulator, could possibly hold a 32 bit value, we don't really want to
support such a split.  This patch adds two tweaks to avoid situations
such as this.

Committed as 119055.


Bernd
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 119049)
+++ ChangeLog	(working copy)
@@ -9,6 +9,11 @@
 	(add_to_reg): Renamed from add_to_sp.  All callers changed.  Lose some
 	dead code.
 
+	* config/bfin/bfin.c (hard_regno_mode_ok): Only allow first 31
+	regs for DImode.
+	(bfin_register_move_cost): Bump costs if trying to move plain
+	integer values through accumulators.
+
 2006-11-21  Ben Elliston  <bje@au.ibm.com>
 
 	* config/spu/spu.c (spu_expand_vector_init): Initialise x.
Index: config/bfin/bfin.c
===================================================================
--- config/bfin/bfin.c	(revision 119049)
+++ config/bfin/bfin.c	(working copy)
@@ -1854,10 +1854,16 @@ hard_regno_mode_ok (int regno, enum mach
     return mode == BImode;
   if (mode == PDImode || mode == V2PDImode)
     return regno == REG_A0 || regno == REG_A1;
+
+  /* Allow all normal 32 bit regs, except REG_M3, in case regclass ever comes
+     up with a bad register class (such as ALL_REGS) for DImode.  */
+  if (mode == DImode)
+    return regno < REG_M3;
+
   if (mode == SImode
       && TEST_HARD_REG_BIT (reg_class_contents[PROLOGUE_REGS], regno))
     return 1;
-      
+
   return TEST_HARD_REG_BIT (reg_class_contents[MOST_REGS], regno);
 }
 
@@ -1873,7 +1879,7 @@ bfin_vector_mode_supported_p (enum machi
    one in class CLASS2.  A cost of 2 is the default.  */
 
 int
-bfin_register_move_cost (enum machine_mode mode ATTRIBUTE_UNUSED,
+bfin_register_move_cost (enum machine_mode mode,
 			 enum reg_class class1, enum reg_class class2)
 {
   /* These need secondary reloads, so they're more expensive.  */
@@ -1891,6 +1897,15 @@ bfin_register_move_cost (enum machine_mo
   if (class1 == DREGS && class2 != DREGS)
     return 2 * 2;
 
+  if (GET_MODE_CLASS (mode) == MODE_INT)
+    {
+      /* Discourage trying to use the accumulators.  */
+      if (TEST_HARD_REG_BIT (reg_class_contents[class1], REG_A0)
+	  || TEST_HARD_REG_BIT (reg_class_contents[class1], REG_A1)
+	  || TEST_HARD_REG_BIT (reg_class_contents[class2], REG_A0)
+	  || TEST_HARD_REG_BIT (reg_class_contents[class2], REG_A1))
+	return 20;
+    }
   return 2;
 }
 

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