[llvm] [CodeGenPrepare] Folding `urem` with loop invariant value as remainder (PR #96625)

[Yingwei Zheng via llvm-commits]

================
@@ -0,0 +1,884 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s
----------------
dtcxzyw wrote:

llc runs `LoopSimplify` before `CodeGenPrepare`, which introduces pre-headers for loops in `InsertPreheaderForLoop`.

See also https://github.com/llvm/llvm-project/blob/f0eb5587ceeb641445b64cb264c822b4751de04a/llvm/test/CodeGen/RISCV/O3-pipeline.ll#L42-L73

`Canonicalize natural loops` stands for `LoopSimplify`.



https://github.com/llvm/llvm-project/pull/96625