On 5/16/23 06:35, Ajit Agarwal wrote:
On 29/04/23 5:03 am, Jeff Law wrote:
On 4/28/23 16:42, Hans-Peter Nilsson wrote:
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?
I don't think you missed anything. That was one of the points I was making
last week. Somewhere, somehow we need to describe what the ABI mandates and
guarantees.
So while what Ajit has done is a step forward, at some point the actual details
of the ABI need to be described in a way that can be checked and consumed by
REE.
The ABI we need for ree pass are the argument registers and return registers.
Based on that I have described interfaces that we need. Other than that we dont
any other ABI hooks. I have used FUNCTION_VALUE_REGNO_P and
FuNCTION_ARG_REGNO_P abi hooks.
You're working with one of many ABIs, some of which have useful
properties, some of which do not.
Simply testing FUNCTION_VALUE_REGNO_P/FUNCTION_ARG_REGNO_P is not
sufficient. You need to be able to query the ABI properties.
jeff
