re PR target/19653 (x87 reg allocated for constants for -mfpmath=sse)

2005-08-08  Paolo Bonzini  <bonzini@gnu.org>
	    Dale Johannesen  <dalej@apple.com>

	PR target/19653
	* regclass.c (struct reg_pref): Update documentation.
	(regclass): Set prefclass to NO_REGS if memory is the best option.
	(record_reg_classes): Cope with a prefclass set to NO_REGS.
	* reload.c (find_reloads): Take PREFERRED_OUTPUT_RELOAD_CLASS
	into account.  For non-registers, equate an empty preferred
	reload class to a `!' in the constraint; move the if clause to
	do so after those that reject the insn.
	(push_reload): Allow PREFERRED_*_RELOAD_CLASS to liberally
	return NO_REGS.
	(find_dummy_reload): Likewise.
	* doc/tm.texi (Register Classes): Document what it means
	if PREFERRED_*_RELOAD_CLASS return NO_REGS.
	* config/i386/i386.c (ix86_preferred_reload_class): Force
	using SSE registers (and return NO_REGS for floating-point
	constants) if math is done with SSE.
	(ix86_preferred_output_reload_class): New.
	* config/i386/i386-protos.h (ix86_preferred_output_reload_class): New.
	* config/i386/i386.h (PREFERRED_OUTPUT_RELOAD_CLASS): New.
	* config/i386/i386.md: Remove # register preferences.


Co-Authored-By: Dale Johannesen <dalej@apple.com>

From-SVN: r112637

1 files changed, 41 insertions, 18 deletions

diff --git a/gcc/reload.c b/gcc/reload.c
index 9bfb748..f3023ae 100644
--- a/gcc/reload.c
+++ b/gcc/reload.c
@@ -1184,15 +1184,24 @@ push_reload (rtx in, rtx out, rtx *inloc, rtx *outloc,
 
   /* Narrow down the class of register wanted if that is
      desirable on this machine for efficiency.  */
-  if (in != 0)
-    class = PREFERRED_RELOAD_CLASS (in, class);
+  {
+    enum reg_class preferred_class = class;
+
+    if (in != 0)
+      preferred_class = PREFERRED_RELOAD_CLASS (in, class);
 
   /* Output reloads may need analogous treatment, different in detail.  */
 #ifdef PREFERRED_OUTPUT_RELOAD_CLASS
-  if (out != 0)
-    class = PREFERRED_OUTPUT_RELOAD_CLASS (out, class);
+    if (out != 0)
+      preferred_class = PREFERRED_OUTPUT_RELOAD_CLASS (out, preferred_class);
 #endif
 
+    /* Discard what the target said if we cannot do it.  */
+    if (preferred_class != NO_REGS
+	|| (optional && type == RELOAD_FOR_OUTPUT))
+      class = preferred_class;
+  }
+
   /* Make sure we use a class that can handle the actual pseudo
      inside any subreg.  For example, on the 386, QImode regs
      can appear within SImode subregs.  Although GENERAL_REGS
@@ -1885,7 +1894,11 @@ find_dummy_reload (rtx real_in, rtx real_out, rtx *inloc, rtx *outloc,
 
   /* Narrow down the reg class, the same way push_reload will;
      otherwise we might find a dummy now, but push_reload won't.  */
-  class = PREFERRED_RELOAD_CLASS (in, class);
+  {
+    enum reg_class preferred_class = PREFERRED_RELOAD_CLASS (in, class);
+    if (class != NO_REGS)
+      class = preferred_class;
+  }
 
   /* See if OUT will do.  */
   if (REG_P (out)
@@ -3401,22 +3414,10 @@ find_reloads (rtx insn, int replace, int ind_levels, int live_known,
 		    losers++;
 		}
 
-	      /* If we can't reload this value at all, reject this
-		 alternative.  Note that we could also lose due to
-		 LIMIT_RELOAD_RELOAD_CLASS, but we don't check that
-		 here.  */
-
-	      if (! CONSTANT_P (operand)
-		  && (enum reg_class) this_alternative[i] != NO_REGS
-		  && (PREFERRED_RELOAD_CLASS (operand,
-					      (enum reg_class) this_alternative[i])
-		      == NO_REGS))
-		bad = 1;
-
 	      /* Alternative loses if it requires a type of reload not
 		 permitted for this insn.  We can always reload SCRATCH
 		 and objects with a REG_UNUSED note.  */
-	      else if (GET_CODE (operand) != SCRATCH
+	      if (GET_CODE (operand) != SCRATCH
 		       && modified[i] != RELOAD_READ && no_output_reloads
 		       && ! find_reg_note (insn, REG_UNUSED, operand))
 		bad = 1;
@@ -3424,6 +3425,28 @@ find_reloads (rtx insn, int replace, int ind_levels, int live_known,
 		       && ! const_to_mem)
 		bad = 1;
 
+	      /* If we can't reload this value at all, reject this
+		 alternative.  Note that we could also lose due to
+		 LIMIT_RELOAD_CLASS, but we don't check that
+		 here.  */
+
+	      if (! CONSTANT_P (operand)
+		  && (enum reg_class) this_alternative[i] != NO_REGS)
+		{
+		  if (PREFERRED_RELOAD_CLASS
+			(operand, (enum reg_class) this_alternative[i])
+		      == NO_REGS)
+		    reject = 600;
+
+#ifdef PREFERRED_OUTPUT_RELOAD_CLASS
+		  if (operand_type[i] == RELOAD_FOR_OUTPUT
+		      && PREFERRED_OUTPUT_RELOAD_CLASS
+			   (operand, (enum reg_class) this_alternative[i])
+		         == NO_REGS)
+		    reject = 600;
+#endif
+		}
+
 	      /* We prefer to reload pseudos over reloading other things,
 		 since such reloads may be able to be eliminated later.
 		 If we are reloading a SCRATCH, we won't be generating any