[llvm] [RISCV] Optimize divide by constant for VP intrinsics (PR #125991)

[Craig Topper via llvm-commits]

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@@ -0,0 +1,113 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=riscv64 -mattr=+zve64x -verify-machineinstrs | FileCheck %s
+
+declare <vscale x 1 x i64> @llvm.vp.udiv.nxv1i64(<vscale x 1 x i64>, <vscale x 1 x i64>, <vscale x 1 x i1>, i32)
+declare <vscale x 1 x i64> @llvm.vp.sdiv.nxv1i64(<vscale x 1 x i64>, <vscale x 1 x i64>, <vscale x 1 x i1>, i32)
+declare <vscale x 1 x i64> @llvm.vp.urem.nxv1i64(<vscale x 1 x i64>, <vscale x 1 x i64>, <vscale x 1 x i1>, i32)
+declare <vscale x 1 x i64> @llvm.vp.srem.nxv1i64(<vscale x 1 x i64>, <vscale x 1 x i64>, <vscale x 1 x i1>, i32)
+declare <vscale x 1 x i64> @llvm.vp.shl.nxv1i64(<vscale x 1 x i64>, <vscale x 1 x i64>, <vscale x 1 x i1>, i32)
+
+
+define <vscale x 1 x i64> @vpudiv_by_const_no_add_nxv1i64(<vscale x 1 x i64> %va, <vscale x 1 x i1> %m, i32 zeroext %evl) {
+; CHECK-LABEL: vpudiv_by_const_no_add_nxv1i64:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    li a1, 5
+; CHECK-NEXT:    vsetvli zero, a0, e64, m1, ta, ma
+; CHECK-NEXT:    vdivu.vx v8, v8, a1, v0.t
+; CHECK-NEXT:    ret
+  %vec = insertelement <vscale x 1 x i64> undef, i64 5, i32 0
+  %splat = shufflevector <vscale x 1 x i64> %vec, <vscale x 1 x i64> poison, <vscale x 1 x i32> zeroinitializer
----------------
topperc wrote:

This wasn't a request to use vp.splat. It was a request to use a splat constant expression `<vscale x 1 x i64> splat (i64 5)` as the argument to `llvm.vp.udiv.nxv1i64`. This is a relatively new syntax that was added last year.

```
%v = call <vscale x 1 x i64> @llvm.vp.udiv.nxv1i64(<vscale x 1 x i64> %va, <vscale x 1 x i64> splat (i64 5), <vscale x 1 x i1> %m, i32 %evl)
```

https://github.com/llvm/llvm-project/pull/125991