[llvm-commits] [PATCH 2/2] FIx PR12312

[Michael Liao]

Hi

This patch is to fix http://llvm.org/bugs/show_bug.cgi?id=12312, where a
special use of i128 needs efficient code generation with PTEST from
SSE4.1.

To fix this issue, 2 patches are developed. The second part is to
recognize that special use, casting from <4 x i32> to i128 followed by a
zero (or non-zero) checking. That sequence is lowered into OR
(X86ISD::OR at the root) tree with all leaves extracted from that vector
because i128 is mapped onto GPR pair. The attached patch adds a
X86-specific DAG optimization to recognize this OR'd tree and convert it
a PTEST if only the flag value is used from that X86ISD::OR root node.

Yours
- Michael
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