[PATCH] D99509: [RISCV] Add legality check for vectoring reduction

[Fraser Cormack via Phabricator via llvm-commits]

frasercrmck added inline comments.


================
Comment at: llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h:135
+
+    if (!VF.isScalable())
+      return true;
----------------
I'm wondering if returning `true`  for fixed-length vectors, even if correct (i.e. not crashing), is likely to produce worse code. Will it trick the cost modeling into producing code which we'll then expand during legalization, and increase register pressure and the likelihood of spilling?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D99509/new/

https://reviews.llvm.org/D99509