[PATCH] D61918: [DAGCombiner] visitShiftByConstant(): drop bogus(?) signbit check

Wed May 15 10:02:41 PDT 2019

spatel added inline comments.

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Comment at: test/CodeGen/X86/xor.ll:496-498
   %neg = shl i64 %intval, 32
   %sext = xor i64 %neg, -4294967296
   %idx.ext = ashr exact i64 %sext, 32
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This test (and the 1 below here) wasn't resulting in 'not' asm before rL347478, so I was trying to make that happen.

This diff seems like a (slight) regression because we're turning a 32-bit 'not' into a 64-bit 'not' (extra prefix byte?), but I'm not sure if anyone cares.

Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D61918/new/

https://reviews.llvm.org/D61918