[PATCH] D124118: [Peephole-Opt] For one kind of test-after-add pattern, eliminates test if it's correct to do so.

[David Li via Phabricator via llvm-commits]

davidxl added inline comments.


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Comment at: llvm/test/CodeGen/X86/peephole-test-after-add.mir:23
+    %5 = load i64, ptr %0, align 8
+    %6 = and i64 %5, 3
+    %7 = icmp slt i64 %6, 0
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The and instruction clears SF and upper  bits of the value which means the test instruction later will also produce SF == 0. In other words, in this case,  not only the test instruction, but also the CMOVErr can be optimized into a copy.  

(this can be looked at in a follow up patch if it is the case).


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D124118/new/

https://reviews.llvm.org/D124118