From 6b13fccda2f9444a1fa7596564ccc845130ad975 Mon Sep 17 00:00:00 2001 From: Luke Lau Date: Thu, 14 Aug 2025 13:41:35 +0800 Subject: [PATCH 1/2] [RISCV] Add a release note about tail folding being enabled. NFC It's probably useful for users to know how to get the old scalar epilogue back if they need it. --- llvm/docs/ReleaseNotes.md | 3 +++ 1 file changed, 3 insertions(+) diff --git a/llvm/docs/ReleaseNotes.md b/llvm/docs/ReleaseNotes.md index 88b7e6d6585f7..f3ef70a01375c 100644 --- a/llvm/docs/ReleaseNotes.md +++ b/llvm/docs/ReleaseNotes.md @@ -109,6 +109,9 @@ Changes to the PowerPC Backend Changes to the RISC-V Backend ----------------------------- +* The loop vectorizer now performs tail folding by default on RISC-V, which + removes the need for a scalar epilogue loop. To restore the previous behaviour + use `-mllvm -prefer-predicate-over-epilogue=scalar-epilogue`. * `llvm-objdump` now has basic support for switching between disassembling code and data using mapping symbols such as `$x` and `$d`. Switching architectures using `$x` with an architecture string suffix is not yet supported. From b2d5bce19d490514384d0622ad19d6c1a69678b9 Mon Sep 17 00:00:00 2001 From: Luke Lau Date: Fri, 15 Aug 2025 11:50:41 +0800 Subject: [PATCH 2/2] Drop -mllvm from the flag Hopefully users can figure out they need to pass -mllvm on Clang --- llvm/docs/ReleaseNotes.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/llvm/docs/ReleaseNotes.md b/llvm/docs/ReleaseNotes.md index f3ef70a01375c..01efeae63c499 100644 --- a/llvm/docs/ReleaseNotes.md +++ b/llvm/docs/ReleaseNotes.md @@ -111,7 +111,7 @@ Changes to the RISC-V Backend * The loop vectorizer now performs tail folding by default on RISC-V, which removes the need for a scalar epilogue loop. To restore the previous behaviour - use `-mllvm -prefer-predicate-over-epilogue=scalar-epilogue`. + use `-prefer-predicate-over-epilogue=scalar-epilogue`. * `llvm-objdump` now has basic support for switching between disassembling code and data using mapping symbols such as `$x` and `$d`. Switching architectures using `$x` with an architecture string suffix is not yet supported.