On Sat, 22 Apr 2023, Ajit Agarwal via Gcc-patches wrote:
> Hello All:
>
> This new version of patch 4 use improve ree pass for rs6000 target using
> defined ABI interfaces.
> Bootstrapped and regtested on power64-linux-gnu.
>
> Thanks & Regards
> Ajit
>
>
> ree: Improve ree pass for rs6000 target using defined abi interfaces
>
> For rs6000 target we see redundant zero and sign
> extension and done to improve ree pass to eliminate
> such redundant zero and sign extension using defines
> ABI interfaces.
>
> 2023-04-22 Ajit Kumar Agarwal <aagar...@linux.ibm.com>
>
> gcc/ChangeLog:
>
> * ree.cc (combline_reaching_defs): Add zero_extend
> using defined abi interfaces.
> (add_removable_extension): use of defined abi interfaces
> for no reaching defs.
> (abi_extension_candidate_return_reg_p): New defined ABI function.
> (abi_extension_candidate_p): New defined ABI function.
> (abi_extension_candidate_argno_p): New defined ABI function.
> (abi_handle_regs_without_defs_p): New defined ABI function.
>
> gcc/testsuite/ChangeLog:
>
> * g++.target/powerpc/zext-elim-3.C
> ---
> gcc/ree.cc | 176 +++++++++++++++---
> .../g++.target/powerpc/zext-elim-3.C | 16 ++
> 2 files changed, 162 insertions(+), 30 deletions(-)
> create mode 100644 gcc/testsuite/g++.target/powerpc/zext-elim-3.C
>
> diff --git a/gcc/ree.cc b/gcc/ree.cc
> index 413aec7c8eb..0de96b1ece1 100644
> --- a/gcc/ree.cc
> +++ b/gcc/ree.cc
> @@ -473,7 +473,8 @@ get_defs (rtx_insn *insn, rtx reg, vec<rtx_insn *> *dest)
> break;
> }
>
> - gcc_assert (use != NULL);
> + if (use == NULL)
> + return NULL;
>
> ref_chain = DF_REF_CHAIN (use);
>
> @@ -514,7 +515,8 @@ get_uses (rtx_insn *insn, rtx reg)
> if (REGNO (DF_REF_REG (def)) == REGNO (reg))
> break;
>
> - gcc_assert (def != NULL);
> + if (def == NULL)
> + return NULL;
>
> ref_chain = DF_REF_CHAIN (def);
>
> @@ -750,6 +752,103 @@ get_extended_src_reg (rtx src)
> return src;
> }
>
> +/* Return TRUE if the candidate insn is zero extend and regno is
> + an return registers. */
> +
> +static bool
> +abi_extension_candidate_return_reg_p (rtx_insn *insn, int regno)
> +{
> + rtx set = single_set (insn);
> +
> + if (GET_CODE (SET_SRC (set)) != ZERO_EXTEND)
> + return false;
> +
> + if (FUNCTION_VALUE_REGNO_P (regno))
> + return true;
> +
> + return false;
> +}
> +
> +/* Return TRUE if reg source operand of zero_extend is argument registers
> + and not return registers and source and destination operand are same
> + and mode of source and destination operand are not same. */
> +
> +static bool
> +abi_extension_candidate_p (rtx_insn *insn)
> +{
> + rtx set = single_set (insn);
> +
> + if (GET_CODE (SET_SRC (set)) != ZERO_EXTEND)
> + return false;
> +
> + machine_mode ext_dst_mode = GET_MODE (SET_DEST (set));
> + rtx orig_src = XEXP (SET_SRC (set),0);
> +
> + bool copy_needed
> + = (REGNO (SET_DEST (set)) != REGNO (XEXP (SET_SRC (set), 0)));
> +
> + if (!copy_needed && ext_dst_mode != GET_MODE (orig_src)
> + && FUNCTION_ARG_REGNO_P (REGNO (orig_src))
> + && !abi_extension_candidate_return_reg_p (insn, REGNO (orig_src)))
> + return true;
> +
> + return false;
> +}
> +
> +/* Return TRUE if the candidate insn is zero extend and regno is
> + an argument registers. */
> +
> +static bool
> +abi_extension_candidate_argno_p (rtx_code code, int regno)
> +{
> + if (code != ZERO_EXTEND)
> + return false;
> +
> + if (FUNCTION_ARG_REGNO_P (regno))
> + return true;
> +
> + return false;
> +}
I don't see anything in those functions that checks if
ZERO_EXTEND is actually a feature of the ABI, e.g. as opposed to
no extension or SIGN_EXTEND. Do I miss something?
Also, "!= ZERO_EXTEND" has too many spaces, copy-pasted in
several (all?) places.
Also, s/an return registers/a return register/ (three errors).
brgds, H-P
