[LLVMdev] State of 'llvm.pcmarker' Intrinsic

Andrew Lenharth andrewl at lenharth.org
Mon Feb 8 11:25:56 PST 2010

On Mon, Feb 8, 2010 at 1:13 PM, Nathan McCauley
<nathan.mccauley at gmail.com> wrote:
> Hi list,
> For a tool I'm working on I'd like to know where instructions end up in
> compiled executables by looking them up in the symbol table.  Therefore,
> I've been trying to use the  llvm.pcmarker Intrinsic, but I've had no luck.
> When I pass .bc files with this intrinsic into llc, I'm given this error:
> LLVM ERROR: Cannot yet select: 0x2026938: ch PCMarker 0x1f0c678, 0x20268b0
> I've attempted this with programs targeting both x86 and ppc, with the same
> results.

Neither architecture support the intrinsic.

> Is this intrinsic unimplemented at this time?  If so, what kind of effort
> would it take to implement this?

Not much.  Add a pseudo instruction to the backend which generates a
unique label when codegened, at least for linkers that don't reorder
regions delineated by global symbols (linux should be safe).


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