Denis Chertykov schrieb:
> 2011/6/9 Georg-Johann Lay <a...@gjlay.de>:
>> This is a tentative patch to fix PR46779 and hopefully also related
>> issues like PR45291.
>>
> - /* Disallow QImode in stack pointer regs. */
> - if ((regno == REG_SP || regno == (REG_SP + 1)) && mode == QImode)
> + /* Don't allocate data to non-GENERAL_REGS registers. */
> +
> + if (regno >= 32)
> return 0;
>
> I think that we not need in this code.
> GCC core must bother about this.
>
> +
> + if (GET_MODE_SIZE (mode) == 1)
> return 1;
>
> I'm agree with this.
>
> +
> + /* Disallow big registers that overlap the frame pointer.
> + This will hopefully reduce the number of spill failures. */
> +
> + if (GET_MODE_SIZE (mode) > 2
> + && regno <= REG_Y
> + && regno + GET_MODE_SIZE (mode) >= REG_Y + 1)
> + {
> + return 0;
> + }
>
> Fragment from GCC info:
> --------------------------------------
> HARD_REGNO_MODE_OK (regno, mode)A C expression that is nonzero if it
> is permissible to store a value of mode mode in hard register number
> regno (or in several registers starting with that one). For a machine
> where all registers are equivalent, a suitable definition is
>
> #define HARD_REGNO_MODE_OK(REGNO, MODE) 1
>
> You need not include code to check for the numbers of fixed registers,
> because the allocation mechanism considers them to be always occupied.
> -----------------------------------------
> Again, GCC core must bother about this.
>
> - /* Otherwise disallow all regno/mode combinations that span r28:r29. */
> - if (regno <= (REG_Y + 1) && (regno + GET_MODE_SIZE (mode)) >= (REG_Y + 1))
> - return 0;
> -
> - if (mode == QImode)
> - return 1;
> -
> - /* Modes larger than QImode occupy consecutive registers. */
> - if (regno + GET_MODE_SIZE (mode) > FIRST_PSEUDO_REGISTER)
> - return 0;
> -
>
> This is a right change.
>
> Denis.
So the patch turns avr_hard_regno_mode_ok into plain vanilla...
Johann
--
PR target/46779
* config/avr/avr.c (avr_hard_regno_mode_ok): Rewrite.
In particular, allow 8-bit values in r28 and r29.
(avr_hard_regno_scratch_ok): Disallow any register that might be
part of the frame pointer.
(avr_hard_regno_rename_ok): Same.
Index: config/avr/avr.c
===================================================================
--- config/avr/avr.c (Revision 174701)
+++ config/avr/avr.c (Arbeitskopie)
@@ -6276,26 +6276,20 @@ jump_over_one_insn_p (rtx insn, rtx dest
int
avr_hard_regno_mode_ok (int regno, enum machine_mode mode)
{
- /* Disallow QImode in stack pointer regs. */
- if ((regno == REG_SP || regno == (REG_SP + 1)) && mode == QImode)
- return 0;
-
- /* The only thing that can go into registers r28:r29 is a Pmode. */
- if (regno == REG_Y && mode == Pmode)
- return 1;
-
- /* Otherwise disallow all regno/mode combinations that span r28:r29. */
- if (regno <= (REG_Y + 1) && (regno + GET_MODE_SIZE (mode)) >= (REG_Y + 1))
- return 0;
-
- if (mode == QImode)
+ /* Any GENERAL_REGS register can hold 8-bit values. */
+ /* FIXME:
+ 8-bit values must not be disallowed for R28 or R29. Disallowing
+ QI et al. in these registers might lead to code like
+ (set (subreg:QI (reg:HI 28)) ...)
+ which will result in wrong code because reload does not handle
+ SUBREGs of hard regsisters like this. This could be fixed in reload.
+ However, it appears that fixing reload is not wanted by reload people. */
+
+ if (GET_MODE_SIZE (mode) == 1)
return 1;
-
- /* Modes larger than QImode occupy consecutive registers. */
- if (regno + GET_MODE_SIZE (mode) > FIRST_PSEUDO_REGISTER)
- return 0;
-
- /* All modes larger than QImode should start in an even register. */
+
+ /* All modes larger than 8 bits should start in an even register. */
+
return !(regno & 1);
}
@@ -6422,13 +6416,23 @@ avr_hard_regno_scratch_ok (unsigned int
&& !df_regs_ever_live_p (regno))
return false;
+ /* Don't allow hard registers that might be part of the frame pointer.
+ Some places in the compiler just test for [HARD_]FRAME_POINTER_REGNUM
+ and don't care for a frame pointer that spans more than one register. */
+
+ if ((!reload_completed || frame_pointer_needed)
+ && (regno == REG_Y || regno == REG_Y + 1))
+ {
+ return false;
+ }
+
return true;
}
/* Return nonzero if register OLD_REG can be renamed to register NEW_REG. */
int
-avr_hard_regno_rename_ok (unsigned int old_reg ATTRIBUTE_UNUSED,
+avr_hard_regno_rename_ok (unsigned int old_reg,
unsigned int new_reg)
{
/* Interrupt functions can only use registers that have already been
@@ -6439,6 +6443,17 @@ avr_hard_regno_rename_ok (unsigned int o
&& !df_regs_ever_live_p (new_reg))
return 0;
+ /* Don't allow hard registers that might be part of the frame pointer.
+ Some places in the compiler just test for [HARD_]FRAME_POINTER_REGNUM
+ and don't care for a frame pointer that spans more than one register. */
+
+ if ((!reload_completed || frame_pointer_needed)
+ && (old_reg == REG_Y || old_reg == REG_Y + 1
+ || new_reg == REG_Y || new_reg == REG_Y + 1))
+ {
+ return 0;
+ }
+
return 1;
}
