[PATCH] D136319: [GISel] Rework trunc/shl combine in a generic trunc/shift combine

[Jay Foad via Phabricator via llvm-commits]

foad added inline comments.


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Comment at: llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h:415
+  ///    if K <= (MidVT.getScalarSizeInBits() - VT.getScalarSizeInBits())
+  /// MidVT is obtained from TLI using getPreferredShiftAmountTy, so the
+  /// trunc/right shift combine is only applied when that returns a type
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Interesting - this seems like an abuse of getPreferredShiftAmountTy, but I guess it works out OK in practice for the one case we care about (converting 64-bit shifts to 32-bit shifts).


Repository:
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  https://reviews.llvm.org/D136319/new/

https://reviews.llvm.org/D136319