[llvm-dev] LLVM FunctionType cannot be returned as VectorType?
Cranmer, Joshua via llvm-dev
llvm-dev at lists.llvm.org
Mon Jul 23 06:48:42 PDT 2018
In x86 ABI terms, a result that is a vector is returned in %xmm0 (or %ymm0/%zmm0 if the size is >128 bits). All other scalar types are returned via %rax (or some subslice thereof).
The way you’re calling the function is expecting the value to be found in %rax, where the callee is trying to return it in %xmm0, which means you’re reading the results of some scratch register. What you’ll want to do is either use the gcc/clang vector intrinsics to get a vector type for the function call or modify the code to read/write the vectors via memory references rather than passing them as arguments/return values.
From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of Jia Yu via llvm-dev
Sent: Monday, July 23, 2018 6:02
To: stefan.graenitz at gmail.com
Cc: llvm-dev at lists.llvm.org
Subject: Re: [llvm-dev] LLVM FunctionType cannot be returned as VectorType?
Hi Stefan,
Thank you very much for answering my question!
I followed your suggestion but the function still cannot return the correct result. I also set target-feature attributes for my function. I am using LLVM 6.0.
It only prints out some random large numbers but the correct answer is supposed to be all 0.
Can you please help me figure out what's going on here? Any help will be greatly appreciated.
///////////////////////////////////////////////////////////////////////////////////////////
My function prototype definition:
auto vectorDataType = VectorType::get(IntegerType::getIntNTy(TheContext, 64), 4);
std::vector<Type *> vecArguments;
for (Uint64 nodeId = startOfLeaves; nodeId < numNodes; ++nodeId) {
vecArguments.push_back(vectorDataType);
}
proto = FunctionType::get(vectorDataType,//int64*4 = __m256i
vecArguments, false);
///////////////////////////////////////////////////////////////////////////////////////////
The generated IR:
define <4 x i64> @tpchq6(<4 x i64> %leaf7, <4 x i64> %leaf8, <4 x i64> %leaf9, <4 x i64> %leaf10, <4 x i64> %leaf11, <4 x i64> %leaf12, <4 x i64> %leaf13, <4 x i64> %leaf14) #0 {
entry:
%addtmp = add <4 x i64> %leaf8, %leaf7
%addtmp1 = add <4 x i64> %addtmp, %leaf9
%addtmp4 = add <4 x i64> %addtmp1, %leaf10
%addtmp2 = add <4 x i64> %addtmp4, %leaf11
%addtmp3 = add <4 x i64> %addtmp2, %leaf12
%addtmp5 = add <4 x i64> %addtmp3, %leaf13
%addtmp6 = add <4 x i64> %addtmp5, %leaf14
ret <4 x i64> %addtmp6
}
///////////////////////////////////////////////////////////////////////////////////////////
My JIT function call:
using VecInt = int64_t[4];
auto function = (int64_t *(*)(
VecInt
, VecInt
, VecInt
, VecInt
, VecInt
, VecInt
, VecInt
, VecInt
))(TheExecutionEngine->getFunctionAddress(TheFunction->getName().str()));
VecInt argsX = {0,0,0,0};
int64_t* result = function(argsX,argsX,argsX,argsX,argsX,argsX,argsX,argsX);
///////////////////////////////////////////////////////////////////////////////////////////
My output result:
422162285262848 562251371602737 843692813695832 422162285262848
It only prints out some random large numbers but the correct answer is supposed to be all 0.
///////////////////////////////////////////////////////////////////////////////////////////
Thanks,
Jia
------------------------------------
Jia Yu,
Ph.D. Student in Computer Science
Arizona State University<http://www.asu.edu/>
On Sun, Jul 22, 2018 at 8:51 AM Stefan Gränitz <stefan.graenitz at gmail.com<mailto:stefan.graenitz at gmail.com>> wrote:
Hi Jia
I don't think this is a problem with the ExecutionEngine. Your problem comes from the confusion of the "Vector Type" in LLVM IR [1] with the "std::vector" data structure in the C++ STL. While there is no direct relation between the two, you should be able to use a std::vector to provide the input for the <4 x i61> Vector Type by passing the std::vector's raw data [3].
However, it would be easier with something like this:
using VecInt = int64[4];
VecInt args0 { 0, 1, 2, 3 };
...
VecInt result = function(args0, ...);
Btw.: Note that you may need to set target-feature attributes for your function like so: [3]
Hope it helps.
Cheers,
Stefan
[1] https://llvm.org/docs/LangRef.html#vector-type
[2] https://en.cppreference.com/w/cpp/container/vector
[3] https://en.cppreference.com/w/cpp/container/vector/data
[4] https://github.com/weliveindetail/DecisionTreeCompiler/blob/master/compiler/DecisionTreeCompiler.cpp#L83
Am 20.07.18 um 02:02 schrieb Jia Yu via llvm-dev:
Dear all,
I am using LLVM C++ API to generate some code. In particular, I am dealing with AVX2 SIMD API which uses __m256i.
My function input types a set of vectors and return type is also a vector.
///////////////////////////////////////////////////////////////////////////////////////////
arguments.push_back(VectorType::get(IntegerType::getIntNTy(TheContext, 64), 4));//int64*4 = __m256i
FunctionType * proto = FunctionType::get(VectorType::get(IntegerType::getIntNTy(TheContext, 64), 4),//int64*4 = __m256i
arguments, false);
///////////////////////////////////////////////////////////////////////////////////////////
I can successfully use this way to produce the IR of my function properly like this:
///////////////////////////////////////////////////////////////////////////////////////////
define <4 x i64> @tpchq6(<4 x i64> %leaf7, <4 x i64> %leaf8, <4 x i64> %leaf9, <4 x i64> %leaf10, <4 x i64> %leaf11, <4 x i64> %leaf12, <4 x i64> %leaf13, <4 x i64> %leaf14) {
entry:
%addtmp = add <4 x i64> %leaf14, %leaf13
%leaf8.neg = sub <4 x i64> zeroinitializer, %leaf8
%xortmp = xor <4 x i64> %addtmp, %leaf11
%addtmp1 = add <4 x i64> %leaf8.neg, %leaf7
%subtmp = add <4 x i64> %addtmp1, %leaf9
%addtmp2 = add <4 x i64> %subtmp, %leaf10
%addtmp3 = add <4 x i64> %addtmp2, %xortmp
ret <4 x i64> %addtmp3
}
///////////////////////////////////////////////////////////////////////////////////////////
However, when I use JIT ExectionEngine to run it, it cannot return the Vector type properly. I tried the jit execution engine with non-vector return like int64, it works fine.
My code is as follows: It always tells me segment fault
///////////////////////////////////////////////////////////////////////////////////////////
// Define the input/output data type in LLVM function
typedef std::vector<int64_t> VecInt;
auto function = reinterpret_cast<VecInt (*)(VecInt , VecInt, VecInt, VecInt, VecInt, VecInt, VecInt, VecInt)>(TheExecutionEngine->getFunctionAddress(TheFunction->getName().str()));
VecInt result = function(functionCallArgs[0],functionCallArgs[1],functionCallArgs[2],functionCallArgs[3],
functionCallArgs[4],functionCallArgs[5],functionCallArgs[6],functionCallArgs[7]);
std::cout<<"result size "<< result.size()<<"\n";
///////////////////////////////////////////////////////////////////////////////////////////
Can someone tell me whether this is the correct way to retrieve the vector return type? Or is the vector type return supported?
Thanks,
Jia Yu
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