[llvm-commits] PATCH: custom lowering of x86 dec instruction

[Peter Cooper]

Hi

Please review the attached patch to custom lower a load->dec->store sequence for 64-bit integers on x86.

This is required because tablegen currently doesn't have a way to specify that a store pattern (DEC64m in this case) sets the EFLAGS register with a value that is usable by anything reading EFLAGS from the add -1 in the pattern.  

I've also changed code in EmitTest to allow stores to read from the EFLAGS setting instruction as they won't clobber the flags but this then allows EmitTest to avoid generating an explicit compare instruction.

Thanks,
Pete

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