[PATCH] D19803: [AVX512] lowerV4X128VectorShuffle doesn't correctly select input operands .

[Simon Pilgrim via llvm-commits]

RKSimon added inline comments.

================
Comment at: lib/Target/X86/X86ISelLowering.cpp:11562
@@ +11561,3 @@
+
+  // Set Op in case all related indexes are undef.
+  Ops[0] = !Ops[0] ? (!Ops[1] ? V1 : Ops[1]) : Ops[0];
----------------
Why not just set the Ops[] element to UNDEF?

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Comment at: test/CodeGen/X86/vector-shuffle-512-v8.ll:2283
@@ +2282,3 @@
+
+define <8 x double> @shuffle_v8f64_2301undef67(<8 x double> %a0, <8 x double> %a1) {
+; ALL-LABEL: shuffle_v8f64_2301undef67:
----------------
Typically we just use a single 'u' to indicate that the shuffle mask element is undefined. In this case the test would be called: shuffle_v8f64_2301uu67. Similar for the other tests.


Repository:
  rL LLVM

http://reviews.llvm.org/D19803