[PATCH] D88475: [InstCombine] visitTrunc - trunc (lshr (sext A), C) --> (ashr A, C) non-uniform support

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added a comment.

I think this should look closer to: (precommit that before this patch)



================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp:830-855
+  Constant *C;
+  if (match(Src, m_LShr(m_SExt(m_Value(A)), m_Constant(C)))) {
     unsigned AWidth = A->getType()->getScalarSizeInBits();
     unsigned MaxShiftAmt = SrcWidth - std::max(DestWidth, AWidth);
 
     // If the shift is small enough, all zero bits created by the shift are
     // removed by the trunc.
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https://reviews.llvm.org/D88475