[llvm] [DAG] Combine `store + vselect` to `masked_store` (PR #145176)

[Simon Pilgrim via llvm-commits]

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+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc < %s -mtriple=x86_64-- -mattr=+avx     | FileCheck %s -check-prefix=AVX
+; RUN: llc < %s -mtriple=x86_64-- -mattr=+avx2    | FileCheck %s -check-prefix=AVX2
+; RUN: llc < %s -mtriple=x86_64-- -mattr=+avx512f | FileCheck %s -check-prefix=AVX512
+
+
+define void @test_masked_store_success(<8 x i32> %x, ptr %ptr, <8 x i1> %mask) {
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RKSimon wrote:

vXi16 or vXi8 test case would be useful tbh - its up to you whether to keep the -mattr=+avx512f test coverage but you need to add a -mcpu=x86-64-v4 RUN to have proper avx512bw/vl coverage

https://github.com/llvm/llvm-project/pull/145176