[LLVMdev] RegisterCoalescing pass crashes with ImplicitDef registers

Jakob Stoklund Olesen stoklund at 2pi.dk
Sat Oct 20 15:05:11 PDT 2012

On Oct 20, 2012, at 1:23 PM, Vincent Lejeune <vljn at ovi.com> wrote:

> below is an output of "llc -march=r600 -mcpu=cayman -print-before-all -debug-only=regalloc file.shader" command from llvm3.2svn.
> The register coalescing pass crashes when joining vreg12:sel_z with vreg13 registers, because it tries to access the interval liveness of vreg13... which is undefined.
> I don't know if it's a bug of the pass, or if my backend should do something specific before calling the pass.
> It worked with llvm 3.1, I don't know if there was a requirement introduced between 3.1 and current trunk related to register coalescing.

It's probably a simple bug in the new coalescing algorithm. Could you get me a better stack trace from a debug build?


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