diff mbox

PING: PATCH [4/n]: Prepare x32: Permute the conversion and addition if one operand is a constant

Message ID CAMe9rOrhLsBDAjRWr7n+dzPLHA0hvJ=ZjF2Q3143z5-NtOGdjA@mail.gmail.com
State New
Headers show

Commit Message

H.J. Lu July 28, 2011, 5:59 p.m. UTC 
On Thu, Jul 28, 2011 at 2:31 AM, Paolo Bonzini <bonzini@gnu.org> wrote:
> On 07/28/2011 11:30 AM, Uros Bizjak wrote:
>>
>> >  convert_memory_address_addr_space has a special PLUS/MULT case for
>> >  POINTERS_EXTEND_UNSIGNED<  0. ?It turns out that it is also needed
>> >  for all Pmode != ptr_mode cases. ?OK for trunk?
>> >  2011-06-11 ?H.J. Lu ?<hongjiu.lu@intel.com>
>> >
>> >  ? ? ? ?PR middle-end/47727
>> >  ? ? ? ?* explow.c (convert_memory_address_addr_space): Permute the
>> >  ? ? ? ?conversion and addition if one operand is a constant.
>>
>> Do we still need this patch? With recent target changes the testcase
>> from PR can be compiled without problems with a gcc from an unpatched
>> trunk.
>
> Given the communication difficulties, I hope not...
>
> Paolo
>

Here is the updated patch.  OK for trunk?

Thanks.

Comments

H.J. Lu July 29, 2011, 10:32 p.m. UTC | #1 
On Thu, Jul 28, 2011 at 11:34 PM, Paolo Bonzini <bonzini@gnu.org> wrote:
> Ok, you removed ignore_address_wrap_around, so we're almost there.
>
> On 07/28/2011 07:59 PM, H.J. Lu wrote:
>>
>> @@ -712,7 +715,16 @@ convert_modes (enum machine_mode mode, enum
>> machine_mode oldmode, rtx x, int uns
>>    if (GET_CODE (x) == SUBREG&&  SUBREG_PROMOTED_VAR_P (x)
>>        &&  GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))>= GET_MODE_SIZE
>> (mode)
>>        &&  SUBREG_PROMOTED_UNSIGNED_P (x) == unsignedp)
>> -    x = gen_lowpart (mode, x);
>> +    {
>> +      temp = rtl_hooks.gen_lowpart_no_emit (mode, x);
>> +      if (temp)
>> +       x = temp;
>> +      else
>> +       {
>> +         gcc_assert (!no_emit);
>> +         x = gen_lowpart (mode, x);
>> +       }
>> +    }
>
> +    {
> +       /* gen_lowpart_no_emit should always succeed here.  */
> +       x = rtl_hooks.gen_lowpart_no_emit (mode, x);
> +    }
>
>>
>>    if (GET_MODE (x) != VOIDmode)
>>      oldmode = GET_MODE (x);
>> @@ -776,6 +788,10 @@ convert_modes (enum machine_mode mode, enum
>> machine_mode oldmode, rtx x, int uns
>>          return gen_int_mode (val, mode);
>>        }
>>
>> +      temp = rtl_hooks.gen_lowpart_no_emit (mode, x);
>> +      if (temp)
>> +       return temp;
>> +      gcc_assert (!no_emit);
>>        return gen_lowpart (mode, x);
>
> Right now, gen_lowpart_no_emit will never return NULL, so these tests in
> convert_modes are dead.  Instead, please include in your patch mine at
> http://permalink.gmane.org/gmane.comp.gcc.patches/242085 and adjust as
> follows.
>
> +      temp = rtl_hooks.gen_lowpart_no_emit (mode, x);
> +      if (no_emit)
> +        return rtl_hooks.gen_lowpart_no_emit (mode, x);
> +      else
> +        return gen_lowpart (mode, x);
>
>>      }
>
> If it does not work, PLEASE say why instead of posting another "updated
> patch".

The whole approach doesn't work. The testcase at

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49721#c1

shows GCC depends on transforming:

(zero_extend:DI (plus:SI (FOO:SI) (const_int Y)))

to

(plus:DI (zero_extend:DI (FOO:SI)) (const_int Y))

Otherwise we either get compiler crash or wrong codes.
Paolo Bonzini July 30, 2011, 1:17 p.m. UTC | #2 
On Sat, Jul 30, 2011 at 00:32, H.J. Lu <hjl.tools@gmail.com> wrote:
> The whole approach doesn't work. The testcase at
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49721#c1
>
> shows GCC depends on transforming:
>
> (zero_extend:DI (plus:SI (FOO:SI) (const_int Y)))
>
> to
>
> (plus:DI (zero_extend:DI (FOO:SI)) (const_int Y))
>
> Otherwise we either get compiler crash or wrong codes.

Please explain how/why here or in the BZ.  Compiler crashes can be
fixed, wrong code is often a symptom of latent bugs.

Paolo
diff mbox

Patch

2011-07-28  H.J. Lu  <hongjiu.lu@intel.com>

	PR middle-end/49721
	* explow.c (convert_memory_address_addr_space_1): New.
	(convert_memory_address_addr_space): Use it.

	* expr.c (convert_modes_1): New.
	(convert_modes): Use it.

	* expr.h (convert_modes_1): New.

	* rtl.h (convert_memory_address_addr_space_1): New.
	(convert_memory_address_1): Likewise.

	* simplify-rtx.c (simplify_unary_operation_1): Call
	convert_memory_address_1 instead of convert_memory_address.

diff --git a/gcc/explow.c b/gcc/explow.c
index 3c692f4..069a68a 100644
--- a/gcc/explow.c
+++ b/gcc/explow.c
@@ -320,8 +320,9 @@  break_out_memory_refs (rtx x)
    arithmetic insns can be used.  */
 
 rtx
-convert_memory_address_addr_space (enum machine_mode to_mode ATTRIBUTE_UNUSED,
-				   rtx x, addr_space_t as ATTRIBUTE_UNUSED)
+convert_memory_address_addr_space_1 (enum machine_mode to_mode ATTRIBUTE_UNUSED,
+				     rtx x, addr_space_t as ATTRIBUTE_UNUSED,
+				     bool no_emit ATTRIBUTE_UNUSED)
 {
 #ifndef POINTERS_EXTEND_UNSIGNED
   gcc_assert (GET_MODE (x) == to_mode || GET_MODE (x) == VOIDmode);
@@ -377,28 +378,27 @@  convert_memory_address_addr_space (enum machine_mode to_mode ATTRIBUTE_UNUSED,
       break;
 
     case CONST:
-      return gen_rtx_CONST (to_mode,
-			    convert_memory_address_addr_space
-			      (to_mode, XEXP (x, 0), as));
+      temp = convert_memory_address_addr_space_1 (to_mode, XEXP (x, 0),
+						  as, no_emit);
+      return temp ? gen_rtx_CONST (to_mode, temp) : temp;
       break;
 
     case PLUS:
     case MULT:
-      /* For addition we can safely permute the conversion and addition
-	 operation if one operand is a constant and converting the constant
-	 does not change it or if one operand is a constant and we are
-	 using a ptr_extend instruction  (POINTERS_EXTEND_UNSIGNED < 0).
+      /* FIXME: Is this really safe for POINTERS_EXTEND_UNSIGNED < 0?
+         For addition, we can safely permute the conversion and addition
+	 operation if one operand is a constant and we are using a
+	 ptr_extend instruction (POINTERS_EXTEND_UNSIGNED < 0).
+	 
 	 We can always safely permute them if we are making the address
 	 narrower.  */
       if (GET_MODE_SIZE (to_mode) < GET_MODE_SIZE (from_mode)
 	  || (GET_CODE (x) == PLUS
 	      && CONST_INT_P (XEXP (x, 1))
-	      && (XEXP (x, 1) == convert_memory_address_addr_space
-				   (to_mode, XEXP (x, 1), as)
-                 || POINTERS_EXTEND_UNSIGNED < 0)))
+	      && POINTERS_EXTEND_UNSIGNED < 0))
 	return gen_rtx_fmt_ee (GET_CODE (x), to_mode,
-			       convert_memory_address_addr_space
-				 (to_mode, XEXP (x, 0), as),
+			       convert_memory_address_addr_space_1
+				 (to_mode, XEXP (x, 0), as, no_emit),
 			       XEXP (x, 1));
       break;
 
@@ -406,10 +406,17 @@  convert_memory_address_addr_space (enum machine_mode to_mode ATTRIBUTE_UNUSED,
       break;
     }
 
-  return convert_modes (to_mode, from_mode,
-			x, POINTERS_EXTEND_UNSIGNED);
+  return convert_modes_1 (to_mode, from_mode, x,
+			  POINTERS_EXTEND_UNSIGNED, no_emit);
 #endif /* defined(POINTERS_EXTEND_UNSIGNED) */
 }
+
+rtx
+convert_memory_address_addr_space (enum machine_mode to_mode,
+				   rtx x, addr_space_t as)
+{
+  return convert_memory_address_addr_space_1 (to_mode, x, as, false);
+}
 
 /* Return something equivalent to X but valid as a memory address for something
    of mode MODE in the named address space AS.  When X is not itself valid,
diff --git a/gcc/expr.c b/gcc/expr.c
index 0988c51..8aec0a5 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -696,13 +696,16 @@  convert_to_mode (enum machine_mode mode, rtx x, int unsignedp)
    Both modes may be floating, or both integer.
    UNSIGNEDP is nonzero if X is an unsigned value.
 
+   If NO_EMIT is true, don't emit any instructions.
+
    This can be done by referring to a part of X in place
    or by copying to a new temporary with conversion.
 
    You can give VOIDmode for OLDMODE, if you are sure X has a nonvoid mode.  */
 
 rtx
-convert_modes (enum machine_mode mode, enum machine_mode oldmode, rtx x, int unsignedp)
+convert_modes_1 (enum machine_mode mode, enum machine_mode oldmode,
+		 rtx x, int unsignedp, bool no_emit)
 {
   rtx temp;
 
@@ -712,7 +715,16 @@  convert_modes (enum machine_mode mode, enum machine_mode oldmode, rtx x, int uns
   if (GET_CODE (x) == SUBREG && SUBREG_PROMOTED_VAR_P (x)
       && GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))) >= GET_MODE_SIZE (mode)
       && SUBREG_PROMOTED_UNSIGNED_P (x) == unsignedp)
-    x = gen_lowpart (mode, x);
+    {
+      temp = rtl_hooks.gen_lowpart_no_emit (mode, x);
+      if (temp)
+	x = temp;
+      else
+	{
+	  gcc_assert (!no_emit);
+	  x = gen_lowpart (mode, x);
+	}
+    }
 
   if (GET_MODE (x) != VOIDmode)
     oldmode = GET_MODE (x);
@@ -776,6 +788,10 @@  convert_modes (enum machine_mode mode, enum machine_mode oldmode, rtx x, int uns
 	  return gen_int_mode (val, mode);
 	}
 
+      temp = rtl_hooks.gen_lowpart_no_emit (mode, x);
+      if (temp)
+	return temp;
+      gcc_assert (!no_emit);
       return gen_lowpart (mode, x);
     }
 
@@ -787,10 +803,20 @@  convert_modes (enum machine_mode mode, enum machine_mode oldmode, rtx x, int uns
       return simplify_gen_subreg (mode, x, oldmode, 0);
     }
 
+  if (no_emit)
+    return NULL_RTX;
+
   temp = gen_reg_rtx (mode);
   convert_move (temp, x, unsignedp);
   return temp;
 }
+
+rtx
+convert_modes (enum machine_mode mode, enum machine_mode oldmode,
+	       rtx x, int unsignedp)
+{
+  return convert_modes_1 (mode, oldmode, x, unsignedp, false);
+}
 
 /* Return the largest alignment we can use for doing a move (or store)
    of MAX_PIECES.  ALIGN is the largest alignment we could use.  */
diff --git a/gcc/expr.h b/gcc/expr.h
index 74c608a..dc40196 100644
--- a/gcc/expr.h
+++ b/gcc/expr.h
@@ -267,6 +267,8 @@  extern rtx convert_to_mode (enum machine_mode, rtx, int);
 
 /* Convert an rtx to MODE from OLDMODE and return the result.  */
 extern rtx convert_modes (enum machine_mode, enum machine_mode, rtx, int);
+extern rtx convert_modes_1 (enum machine_mode, enum machine_mode, rtx,
+			    int, bool);
 
 /* Emit code to move a block Y to a block X.  */
 
diff --git a/gcc/rtl.h b/gcc/rtl.h
index 1490bfe..d471efa 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -1658,8 +1658,13 @@  extern int byte_lowpart_offset (enum machine_mode, enum machine_mode);
 extern rtx make_safe_from (rtx, rtx);
 extern rtx convert_memory_address_addr_space (enum machine_mode, rtx,
 					      addr_space_t);
+extern rtx convert_memory_address_addr_space_1 (enum machine_mode, rtx,
+						addr_space_t, bool);
 #define convert_memory_address(to_mode,x) \
 	convert_memory_address_addr_space ((to_mode), (x), ADDR_SPACE_GENERIC)
+#define convert_memory_address_1(to_mode,x,no_emit) \
+	convert_memory_address_addr_space_1 ((to_mode), (x), \
+					     ADDR_SPACE_GENERIC, (no_emit))
 extern const char *get_insn_name (int);
 extern rtx get_last_insn_anywhere (void);
 extern rtx get_first_nonnote_insn (void);
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index 2d7d8dd..6090268 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -1150,7 +1150,7 @@  simplify_unary_operation_1 (enum rtx_code code, enum machine_mode mode, rtx op)
 		  && REG_P (SUBREG_REG (op))
 		  && REG_POINTER (SUBREG_REG (op))
 		  && GET_MODE (SUBREG_REG (op)) == Pmode)))
-	return convert_memory_address (Pmode, op);
+	return convert_memory_address_1 (Pmode, op, true);
 #endif
       break;
 
@@ -1243,7 +1243,7 @@  simplify_unary_operation_1 (enum rtx_code code, enum machine_mode mode, rtx op)
 		  && REG_P (SUBREG_REG (op))
 		  && REG_POINTER (SUBREG_REG (op))
 		  && GET_MODE (SUBREG_REG (op)) == Pmode)))
-	return convert_memory_address (Pmode, op);
+	return convert_memory_address_1 (Pmode, op, true);
 #endif
       break;