[PATCH] D86395: InstCombine transform pattern "(~A & B) ^ A -> (A | B)" added

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

The tests should be pre-committed with current CHECK lines (ie, without this patch), so we just see the diffs - and can confirm that the tests actually represent the patterns shown in the test comments.



================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp:3357
+  // (~A & B) ^ A  -->   (A | B)
+  if (match(Op0, m_c_And(m_Not(m_Value(A)), m_Value(B))) &&
+      match(Op1, m_Specific(A)))
----------------
What about the case where the `and` is Op1?


================
Comment at: llvm/test/Transforms/InstCombine/xor-or.ll:21
+  %4 = and i32 %3, %1
+  %5 = xor i32 %4, %0
+  ret i32 %5
----------------
This test doesn't match the comment.

You need something like this:

```
define i32 @test2(i32 %p, i32 %y) {
  %x = add i32 %p, 42 ; thwart complexity-based canonicalization
  %n = xor i32 %x, -1
  %a = and i32 %n, %y
  %r = xor i32 %x, %a
  ret i32 %r
}

```


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D86395/new/

https://reviews.llvm.org/D86395