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Content-Language: en-US To: Jeff Law , Ajit Agarwal , gcc-patches Cc: Segher Boessenkool , Richard Biener References: <4c0b6b4f-bbc1-8dd0-a91c-ffed028b4873@linux.ibm.com> <365cfb50-4313-d44e-6ffc-77473b20c670@linux.ibm.com> <5834b0cb-dd25-c55f-2cf6-9aa6b8372724@linux.ibm.com> <29ab8ff7-20d5-183f-a0ce-c82758488b64@linux.ibm.com> <1a482ac5-404b-0787-c682-b10d13dc76ee@gmail.com> From: Peter Bergner In-Reply-To: <1a482ac5-404b-0787-c682-b10d13dc76ee@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: Oz9TSdJcvBEr-oveEhfHFr0yMTkg8zxw X-Proofpoint-ORIG-GUID: rlPo8HlV62udRSVCutRVfTv21MkyW1gm X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-03-22_21,2023-03-23_02,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 lowpriorityscore=0 mlxlogscore=999 adultscore=0 spamscore=0 clxscore=1015 suspectscore=0 impostorscore=0 malwarescore=0 priorityscore=1501 phishscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2303150002 definitions=main-2303230120 X-Spam-Status: No, score=-3.7 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_EF,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On 3/23/23 11:32 AM, Jeff Law via Gcc-patches wrote: > On 3/23/23 10:29, Peter Bergner wrote: >> I'm sorry that I don't know how REE works. Why can't it optimize this? >> I see in the REE dump: >> >> (insn 20 18 22 3 (set (reg:DI 4 4) >> (zero_extend:DI (reg:QI 4 4 [orig:120 cD.3556+3 ] [120]))) "pr41742.c":6:41 8 {zero_extendqidi2} (nil)) >> (call_insn 22 20 41 3 (parallel [ >> (set (reg:DI 3 3) >> (call (mem:SI (symbol_ref:DI ("memset") [flags 0x41] ) [0 memsetD.1196 S4 A8]) >> (const_int 64 [0x40]))) >> (use (const_int 0 [0])) >> (clobber (reg:DI 96 lr)) ... >> >> Is there a reason why REE cannot see that our (reg:QI 4) is a param register >> and thus due to our ABI, already correctly sign/zero extended? > > I don't think REE has ever considered exploiting ABI constraints. Handling > that might be a notable improvement on various targets. It'd be a great > place to do some experimentation. Ok, so sounds like a good follow-on project after this patch is reviewed and committed (stage1). Thanks for your input! Peter