[LLVMdev] Intrinsic instruction to switch core

[Silky Arora]

Since the steps on how to create a new instruction in
http://llvm.org/docs/ExtendingLLVM.html point to files which are not
present in LLVM 3.2, I looked at the diffs for a couple of new instructions
(fence, resume etc) that were added some time back, to create my own
SwitchCodeInst.

The following command works fine
opt -load
/home/silkyar/Workspace/32b_llvm/llvm/Debug+Asserts/lib/LLVMTestSwitchCore.so
-testswitchcore test.bc > test_new.bc
but conversion to assembly crashes with the following error -

llc: test_new.bc: error: Invalid ALLOCA record
While deleting: i32 %
Use still stuck around after Def is destroyed:  switchcore i32 1
llc: Value.cpp:79: virtual llvm::Value::~Value(): Assertion `use_empty() &&
"Uses remain when a value is destroyed!"' failed.

The code to insert the new instruction is straight forward -
Value* coreType = ConstantInt::get(llvm::Type::getInt32Ty(F.getContext()),
1);
Instruction* fnp = bbIter->getFirstNonPHI();
SwitchCoreInst::Create(coreType, fnp);

Could someone help me out with this? Does llc require certain files to be
changed for the assembly which are not part of the diff for 'ResumeInst'
that I followed
https://github.com/clang-omp/llvm/commit/dccc03b2423fe65efb5963ae816b99c24fc53374

Thanks,
 Silky


On Sun, Mar 9, 2014 at 1:04 PM, Silky Arora <silkyar at umich.edu> wrote:

> Hi,
>
> I am working on a project that requires me to suggest to the hardware
> simulator (gem5) switch cores from one to another at the start of certain
> basic blocks. Could someone advice me if I should go with introducing a new
> Intrinsic instruction for this purpose. I will be following
> http://llvm.org/docs/ExtendingLLVM.html for this. Gem5 has certain
> reserved op-codes which I can use.
>
> I was thinking of adding the new instruction to Other Ops type but haven't
> quite figured out the whole procedure yet. The instruction requires to have
> one intty argument (that can take values from 0-2) specifying the core type.
> Any help or suggestions would be appreciated.
>
> Regards,
> Silky Arora
> Graduate Student Research Assistant
> University of Michigan
>
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