[llvm] [DAGCombiner] Port custom DAG combine for `rem` from NVPTX (PR #210344)

via llvm-commits llvm-commits at lists.llvm.org
Sun Aug 2 12:03:58 PDT 2026


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def3r wrote:

I tried adding the condition to skip this when both div and rem are legal, and seems like Mips and NVPTX are also skipped in that situation.

Moreover I'm not sure how helpful would that be for this case in PowerPC as well, here's the [llvm mca analysis](https://godbolt.org/#z:OYLghAFBqd5TKALEBjA9gEwKYFFMCWALugE4A0BIEAZgQDbYB2AhgLbYgDkAjF%2BTXRMiAZVQtGIHgBYBQogFUAztgAKAD24AGfgCsp5eiyahjEgJ5KCS8isaoiBIdWaYAwunoBXNkwOuAGQImbAA5HwAjbFIQWQAHdCtHIQ9vXwMEpKcmIJDwtiiY2TtsB2yRIhZSIlSfPx5bbHtkpgqqolywyOjY20rq2vSGpX6O4K6CnukASlt0L1JUTi4ANzYsL0wAalktgCZyLYBmAFItAEEVwhXN/cOD47PLlkxMTbY7nfunrln6bgArPw/FwdOR0Nxzqx6JZrFslPNFtgtic9kc%2BOQiNpfrMANYgAFaQzcaT8NgEokgsEQrj8JQgIlY0G/chwWAoDA4fDEMiUah0RisDjcDGCYRiCScGRyYTKNSaZnkfQHIwmEBmGFWGwlMrOCCuQb1ImBcb5QoZRLEbKGqREzJWoSdM09YZNUotNoDTx1W2NZrlUZO7oxYajG08IkjdpByYh2YIhZLbhXAg3ba7B6nC5rLz0ejbI6HXZZy5KLwRd6fTNPFYvN6YD4PB7SH5/QHA7HgyHQ2FKeGIpYotF7fhMnTTWZIbAvHoQNtcUnkcmE8hU/g0ukMzHYifkfFHABsADo9gAOHgA0%2Bn6TSADsB4BR2khf%2BXCOHcVG%2B3zNmbIQ8AgDl0DYOIGGiPkIAwECwJiPM1gAWjYcQiFILwmFxAQGCIaJ6QgCJOwiYIqnMEV%2BEI1hSHMAB5CJdHdUjyCgjhhCopgYU7HAK2ANwJHoeleH4HA2GMYBJEVQhSHdVNsH4sFsHUUovGwhjgmw18wXoAgIlIYiPBwTsUIIckBPIFZogiRJsAAEWwYSTE0tUfwEIxgCUAA1AhsAAdyouJmAYsVRHESRpUCuUNE7fQGlVUwey1QwtPpSBZnQOIWn4rZEMMuJGBOI4rISLzojiVAD2kRh4LQ3EmHQLymHghyvHUeDgCYLxMqQuIvDygqvNICMtnXMzSFIAgcCSuc/SkvUDW9IYAXIE08mDWIFvtFpwzWy0Whjc1pAWnUPTDOb6gOt1dVaQNTRW/a%2BnaTa7uqXapgBeMBylecgVXTsaS2OC2EQ8QtggFCqumYHuRIUgh3RaZRx3SdpxwGJJvxFdX0XZdKR%2B7hN0ZHdWUQQC0GA0DGAoKhINJmCQH%2BwGWFB9DMPobDSFw/DFXI4iGK5yiaLohwGKY5giFY9jxOwLieLzfiMSEkSxLBCSpLM2T%2BHkxTlJM1Smk7TTtN0rBljBQzjIxYaLJUGy7NE4JQCcmgXPczyfL8kFRXkCUQtkMKVAixVlUMET1Ti6wEoiCaUrS7IMqy0acuwHrCuK0ryuwSr0JquqGuCJqWrajrUC6pO%2BoGobolG8b4Hjc6WhcJh3BOqQFqWiY9q2rIUibi9yHW7JnqKM7/SET0am7ofpsu6NrtjVbHrHtJTvngfVrexNOD2T6P2pbg/voBCkJYYHGdxcGIEhsgYc3%2BGf0RmcUfnTGKW%2Bz9cdsLcxxxPcQAPI4j1vHg14eAXgBGiaQD4DwHmJG%2Bbe6436f13K%2BEcL8d60m/OOWYw0rDOGkEAA%3D%3D%3D).

https://github.com/llvm/llvm-project/pull/210344


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