[PATCH] D118376: [x86] try harder to scalarize a vector load with extracted integer op uses

[Phoebe Wang via Phabricator via llvm-commits]

pengfei added inline comments.


================
Comment at: llvm/lib/Target/X86/X86ISelLowering.cpp:43086-43088
+  // Note: Unlike the related fold for this in DAGCombiner, this is not limited
+  //       to a single-use of the loaded vector. For the reasons above, we
+  //       expect this to be profitable even if it creates an extra load.
----------------
spatel wrote:
> pengfei wrote:
> > Add a regression test for it?
> There are examples of this in the existing tests diffs - we have both a scalar load and vector load from the same address.
> See:
> vec_cast.ll -> define <3 x i16> @h(<3 x i32> %a)
> vec_int_to_fp.ll -> define <2 x double> @sitofp_load_2i64_to_2f64(<2 x i64> *%a)
> 
> We might still be able to do better on those tests, but that demonstrates what I suggested in this comment. Does that make sense? I can try to come up with another case if the existing tests are not clear.
I see your point, it's fine. Thank you.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D118376/new/

https://reviews.llvm.org/D118376