On 9/25/19 9:57 AM, Richard Sandiford wrote:
> Richard Sandiford <richard.sandif...@arm.com> writes:
>> Like with the combine.c patch, this one keeps things simple by
>> invalidating values in partially-clobbered registers, rather than
>> trying to tell whether the value in a partially-clobbered register
>> is actually clobbered or not. Again, this is in principle a bug fix,
>> but probably never matters in practice.
>
> Similary to the combine patch, I've updated this to avoid the
> short "abi" name and use a temporary HARD_REG_SET instead.
>
> Richard
>
>
> 2019-09-25 Richard Sandiford <richard.sandif...@arm.com>
>
> gcc/
> * cse.c: Include regs.h and function-abi.h.
> (invalidate_for_call): Take the call insn as an argument.
> Use insn_callee_abi to get the ABI of the call and invalidate
> partially clobbered registers as well as fully clobbered ones.
> (cse_insn): Update call accordingly.
>
> Index: gcc/cse.c
> ===================================================================
> --- gcc/cse.c 2019-09-17 15:27:11.338066929 +0100
> +++ gcc/cse.c 2019-09-25 16:55:31.202641509 +0100
> @@ -42,6 +42,8 @@ Software Foundation; either version 3, o
> #include "tree-pass.h"
> #include "dbgcnt.h"
> #include "rtl-iter.h"
> +#include "regs.h"
> +#include "function-abi.h"
>
> /* The basic idea of common subexpression elimination is to go
> through the code, keeping a record of expressions that would
> @@ -566,7 +568,6 @@ static void remove_invalid_subreg_refs (
> machine_mode);
> static void rehash_using_reg (rtx);
> static void invalidate_memory (void);
> -static void invalidate_for_call (void);
> static rtx use_related_value (rtx, struct table_elt *);
>
> static inline unsigned canon_hash (rtx, machine_mode);
> @@ -2091,23 +2092,29 @@ rehash_using_reg (rtx x)
> }
>
> /* Remove from the hash table any expression that is a call-clobbered
> - register. Also update their TICK values. */
> + register in INSN. Also update their TICK values. */
>
> static void
> -invalidate_for_call (void)
> +invalidate_for_call (rtx_insn *insn)
> {
> - unsigned int regno, endregno;
> - unsigned int i;
> + unsigned int regno;
> unsigned hash;
> struct table_elt *p, *next;
> int in_table = 0;
> hard_reg_set_iterator hrsi;
>
> - /* Go through all the hard registers. For each that is clobbered in
> - a CALL_INSN, remove the register from quantity chains and update
> + /* Go through all the hard registers. For each that might be clobbered
> + in call insn INSN, remove the register from quantity chains and update
> reg_tick if defined. Also see if any of these registers is currently
> - in the table. */
> - EXECUTE_IF_SET_IN_HARD_REG_SET (regs_invalidated_by_call, 0, regno, hrsi)
> + in the table.
> +
> + ??? We could be more precise for partially-clobbered registers,
> + and only invalidate values that actually occupy the clobbered part
> + of the registers. It doesn't seem worth the effort though, since
> + we shouldn't see this situation much before RA. */
> + HARD_REG_SET callee_clobbers
> + = insn_callee_abi (insn).full_and_partial_reg_clobbers ();
> + EXECUTE_IF_SET_IN_HARD_REG_SET (callee_clobbers, 0, regno, hrsi)
> {
> delete_reg_equiv (regno);
> if (REG_TICK (regno) >= 0)
> @@ -2132,15 +2139,11 @@ invalidate_for_call (void)
> || REGNO (p->exp) >= FIRST_PSEUDO_REGISTER)
> continue;
>
> - regno = REGNO (p->exp);
> - endregno = END_REGNO (p->exp);
> -
> - for (i = regno; i < endregno; i++)
> - if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
> - {
> - remove_from_table (p, hash);
> - break;
> - }
> + /* This must use the same test as above rather than the
> + more accurate clobbers_reg_p. */
> + if (overlaps_hard_reg_set_p (callee_clobbers, GET_MODE (p->exp),
> + REGNO (p->exp)))
Is it worth putting a forward comment to the earlier test to the later
one to help ensure they're kept in sync?
OK with or without that comment update.
