[llvm-dev] Mips unconditionally uses fast-isel?

Daniel Sanders via llvm-dev
2015-11-17T15:22:00Z

> -----Original Message-----
> From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of
> Robinson, Paul via llvm-dev
> Sent: 16 November 2015 22:19
> To: llvm-dev at lists.llvm.org
> Subject: [llvm-dev] Mips unconditionally uses fast-isel?
>
> I was mucking around in FastISel, and was surprised to see the test
>   llvm/test/CodeGen/Mips/emergency-spill-slot-near-fp.ll
> failed.  This was surprising because it specifies -fast-isel=false.
>
> Does the Mips code generator use fast-isel even when you ask it not to?
> Thanks,
> --paulr
>
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This seems to be an all-targets bug. There's code in OptLevelChanger
(lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp) that forces Fast ISel to be
enabled for every -O0 function.