[llvm] [X86] Add vXi64 MULHU/MULHS lowering, keeping full-width products scalar (PR #206983)

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``````````bash
git-clang-format --diff origin/main HEAD --extensions cpp -- llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp llvm/lib/Target/X86/X86ISelLowering.cpp --diff_from_common_commit
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``````````diff
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 833033825..a51613b2a 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -1754,7 +1754,8 @@ X86TargetLowering::X86TargetLowering(const X86TargetMachine &TM,
       // on AVX512DQ+VL; without it the schoolbook loses to scalar (esp. AVX2).
       if (Subtarget.hasDQI() && Subtarget.hasVLX())
         setOperationAction(ISD::MULHS, MVT::v4i64, Custom);
-      // Custom so the combiner keeps full products as [SU]MUL_LOHI, not MULH[SU].
+      // Custom so the combiner keeps full products as [SU]MUL_LOHI, not
+      // MULH[SU].
       setOperationAction(ISD::UMUL_LOHI, MVT::v4i64, Custom);
       setOperationAction(ISD::SMUL_LOHI, MVT::v4i64, Custom);
       setOperationAction(ISD::VSELECT, MVT::v32i8, Legal);

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https://github.com/llvm/llvm-project/pull/206983