[PATCH] D36395: [InstCombine] narrow rotate left/right patterns to eliminate zext/trunc (PR34046)

[Sanjay Patel via Phabricator via llvm-commits]

spatel added inline comments.


================
Comment at: lib/Transforms/InstCombine/InstCombineCasts.cpp:484
+  Type *DestTy = Trunc.getType();
+  unsigned NarrowWidth = DestTy->getScalarSizeInBits();
+  if (NarrowWidth != *BitWidthC)
----------------
craig.topper wrote:
> Since we don't support vectors here. Should this be getIntegerBitWidth()?
But we do support vectors - see the 2nd regression test.


================
Comment at: lib/Transforms/InstCombine/InstCombineCasts.cpp:485
+  unsigned NarrowWidth = DestTy->getScalarSizeInBits();
+  if (NarrowWidth != *BitWidthC)
+    return nullptr;
----------------
craig.topper wrote:
> Could you have used m_SpecificInt in the matchers above? to avoid this separate check?
Because we do support vectors, we can't do that?


https://reviews.llvm.org/D36395