[llvm] [X86] Attempt to use VPMADD52L/VPMULUDQ instead of VPMULLQ on slow VPMULLQ targets (or when VPMULLQ is unavailable) (PR #171760)

[Simon Pilgrim via llvm-commits]

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@@ -0,0 +1,110 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu -mcpu=cannonlake | FileCheck %s --check-prefix=CNL
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RKSimon wrote:

Add a second nonVLX line:
```
; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu -mcpu=cannonlake -mattr=-avx512vl | FileCheck %s --check-prefix=NOVLX
```
and also a couple of  lines that just specify attributes (-mattr=+avx512dq,+slow-pmullq etc.)

https://github.com/llvm/llvm-project/pull/171760