tree 33264a8a364eee279dae8b61bcb7b02a3ce54f1b
parent 8bcc9b475c6cedb690a80eb93b19a3b57e455512
author Craig Topper <craig.topper@intel.com> 1547185496 +0000
committer Craig Topper <craig.topper@intel.com> 1547185496 +0000

[X86] Change vXi1 extract_vector_elt lowering to be legal if the index is 0. Add DAG combine to turn scalar_to_vector+extract_vector_elt into extract_subvector.

We were lowering the last step extract_vector_elt to a bitcast+truncate. Change it to use an extract_vector_elt of index 0 instead. Add isel patterns to do the equivalent of what the bitcast would have done. Plus an isel pattern for an any_extend+extract to prevent some regressions.

Finally add a DAG combine to turn v1i1 scalar_to_vector+extract_vector_elt of 0 into an extract_subvector.

This fixes some of the regressions from D350800.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350918 91177308-0d34-0410-b5e6-96231b3b80d8