[PATCH] D103874: [IR] Rename the shufflevector's undef mask to poison

[Simon Pilgrim via Phabricator via cfe-commits]

RKSimon added inline comments.


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Comment at: clang/test/CodeGen/X86/avx-builtins.c:182
   // CHECK-LABEL: test_mm256_castsi128_si256
-  // CHECK: shufflevector <2 x i64> %{{.*}}, <2 x i64> %{{.*}}, <4 x i32> <i32 0, i32 1, i32 undef, i32 undef>
+  // CHECK: shufflevector <2 x i64> %{{.*}}, <2 x i64> %{{.*}}, <4 x i32> <i32 0, i32 1, i32 poison, i32 poison>
   return _mm256_castsi128_si256(A);
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efriedma wrote:
> This change might be visible to user code.
Yes the length changing casts are worrying me as well - we could update the header to insert zero into the upper elements I suppose, in many cases these would be folded away by AVX ops implicitly zeroing the 128-bits. But we'd definitely have the potential for regressions.


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Comment at: clang/test/CodeGen/X86/avx-builtins.c:1239
   // CHECK: shufflevector <4 x float> %{{.*}}, <4 x float> poison, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
   // CHECK: shufflevector <8 x float> %{{.*}}, <8 x float> %{{.*}}, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 8, i32 9, i32 10, i32 11>
   return _mm256_loadu2_m128(A, B);
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These look out of date - D109497 changes the loadu2 codegen to be a single 'concat' shuffle.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D103874/new/

https://reviews.llvm.org/D103874