forked from OSchip/llvm-project
GPGPU: create kernel function skeleton
Create for each kernel a separate LLVM-IR module containing a single function marked as kernel function and taking one pointer for each array referenced by this kernel. Add debugging output to verify the kernels are generated correctly. llvm-svn: 275952
This commit is contained in:
Tobias Grosser
parent
651777da8b
commit
32837fe313
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@ -51,6 +51,11 @@ static cl::opt<bool>
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cl::desc("Dump C code describing the GPU mapping"), cl::Hidden,
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cl::init(false), cl::ZeroOrMore, cl::cat(PollyCategory));
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static cl::opt<bool> DumpKernelIR("polly-acc-dump-kernel-ir",
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cl::desc("Dump the kernel LLVM-IR"),
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cl::Hidden, cl::init(false), cl::ZeroOrMore,
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cl::cat(PollyCategory));
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/// Create the ast expressions for a ScopStmt.
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///
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/// This function is a callback for to generate the ast expressions for each
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@ -80,10 +85,18 @@ class GPUNodeBuilder : public IslNodeBuilder {
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public:
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GPUNodeBuilder(PollyIRBuilder &Builder, ScopAnnotator &Annotator, Pass *P,
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const DataLayout &DL, LoopInfo &LI, ScalarEvolution &SE,
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DominatorTree &DT, Scop &S)
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: IslNodeBuilder(Builder, Annotator, P, DL, LI, SE, DT, S) {}
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DominatorTree &DT, Scop &S, gpu_prog *Prog)
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: IslNodeBuilder(Builder, Annotator, P, DL, LI, SE, DT, S), Prog(Prog) {}
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private:
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/// A module containing GPU code.
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///
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/// This pointer is only set in case we are currently generating GPU code.
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std::unique_ptr<Module> GPUModule;
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/// The GPU program we generate code for.
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gpu_prog *Prog;
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/// Create code for user-defined AST nodes.
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///
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/// These AST nodes can be of type:
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@ -94,13 +107,145 @@ private:
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///
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/// @param UserStmt The ast node to generate code for.
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virtual void createUser(__isl_take isl_ast_node *UserStmt);
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/// Create GPU kernel.
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///
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/// Code generate the kernel described by @p KernelStmt.
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///
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/// @param KernelStmt The ast node to generate kernel code for.
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void createKernel(__isl_take isl_ast_node *KernelStmt);
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/// Create kernel function.
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///
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/// Create a kernel function located in a newly created module that can serve
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/// as target for device code generation. Set the Builder to point to the
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/// start block of this newly created function.
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///
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/// @param Kernel The kernel to generate code for.
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void createKernelFunction(ppcg_kernel *Kernel);
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/// Create the declaration of a kernel function.
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///
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/// The kernel function takes as arguments:
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///
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/// - One i8 pointer for each external array reference used in the kernel.
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/// - Host iterators (TODO)
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/// - Parameters (TODO)
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/// - Other LLVM Value references (TODO)
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///
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/// @param Kernel The kernel to generate the function declaration for.
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/// @returns The newly declared function.
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Function *createKernelFunctionDecl(ppcg_kernel *Kernel);
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/// Finalize the generation of the kernel function.
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///
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/// Free the LLVM-IR module corresponding to the kernel and -- if requested --
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/// dump its IR to stderr.
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void finalizeKernelFunction();
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};
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void GPUNodeBuilder::createUser(__isl_take isl_ast_node *UserStmt) {
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isl_ast_expr *Expr = isl_ast_node_user_get_expr(UserStmt);
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isl_ast_expr *StmtExpr = isl_ast_expr_get_op_arg(Expr, 0);
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isl_id *Id = isl_ast_expr_get_id(StmtExpr);
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isl_id_free(Id);
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isl_ast_expr_free(StmtExpr);
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const char *Str = isl_id_get_name(Id);
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if (!strcmp(Str, "kernel")) {
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createKernel(UserStmt);
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isl_ast_expr_free(Expr);
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return;
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}
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isl_ast_expr_free(Expr);
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isl_ast_node_free(UserStmt);
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return;
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}
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void GPUNodeBuilder::createKernel(__isl_take isl_ast_node *KernelStmt) {
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isl_id *Id = isl_ast_node_get_annotation(KernelStmt);
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ppcg_kernel *Kernel = (ppcg_kernel *)isl_id_get_user(Id);
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isl_id_free(Id);
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isl_ast_node_free(KernelStmt);
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assert(Kernel->tree && "Device AST of kernel node is empty");
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Instruction &HostInsertPoint = *Builder.GetInsertPoint();
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createKernelFunction(Kernel);
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Builder.SetInsertPoint(&HostInsertPoint);
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finalizeKernelFunction();
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}
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/// Compute the DataLayout string for the NVPTX backend.
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///
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/// @param is64Bit Are we looking for a 64 bit architecture?
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static std::string computeNVPTXDataLayout(bool is64Bit) {
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std::string Ret = "e";
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if (!is64Bit)
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Ret += "-p:32:32";
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Ret += "-i64:64-v16:16-v32:32-n16:32:64";
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return Ret;
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}
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Function *GPUNodeBuilder::createKernelFunctionDecl(ppcg_kernel *Kernel) {
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std::vector<Type *> Args;
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std::string Identifier = "kernel_" + std::to_string(Kernel->id);
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for (long i = 0; i < Prog->n_array; i++) {
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if (!ppcg_kernel_requires_array_argument(Kernel, i))
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continue;
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Args.push_back(Builder.getInt8PtrTy());
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}
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auto *FT = FunctionType::get(Builder.getVoidTy(), Args, false);
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auto *FN = Function::Create(FT, Function::ExternalLinkage, Identifier,
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GPUModule.get());
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FN->setCallingConv(CallingConv::PTX_Kernel);
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auto Arg = FN->arg_begin();
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for (long i = 0; i < Kernel->n_array; i++) {
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if (!ppcg_kernel_requires_array_argument(Kernel, i))
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continue;
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Arg->setName(Prog->array[i].name);
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Arg++;
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}
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return FN;
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}
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void GPUNodeBuilder::createKernelFunction(ppcg_kernel *Kernel) {
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std::string Identifier = "kernel_" + std::to_string(Kernel->id);
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GPUModule.reset(new Module(Identifier, Builder.getContext()));
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GPUModule->setTargetTriple(Triple::normalize("nvptx64-nvidia-cuda"));
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GPUModule->setDataLayout(computeNVPTXDataLayout(true /* is64Bit */));
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Function *FN = createKernelFunctionDecl(Kernel);
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auto EntryBlock = BasicBlock::Create(Builder.getContext(), "entry", FN);
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Builder.SetInsertPoint(EntryBlock);
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Builder.CreateRetVoid();
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Builder.SetInsertPoint(EntryBlock, EntryBlock->begin());
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}
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void GPUNodeBuilder::finalizeKernelFunction() {
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if (DumpKernelIR)
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outs() << *GPUModule << "\n";
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GPUModule.release();
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}
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namespace {
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class PPCGCodeGeneration : public ScopPass {
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public:
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@ -693,8 +838,9 @@ public:
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/// Generate code for a given GPU AST described by @p Root.
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///
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/// @param An isl_ast_node pointing to the root of the GPU AST.
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void generateCode(__isl_take isl_ast_node *Root) {
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/// @param Root An isl_ast_node pointing to the root of the GPU AST.
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/// @param Prog The GPU Program to generate code for.
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void generateCode(__isl_take isl_ast_node *Root, gpu_prog *Prog) {
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ScopAnnotator Annotator;
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Annotator.buildAliasScopes(*S);
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@ -706,8 +852,8 @@ public:
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PollyIRBuilder Builder = createPollyIRBuilder(EnteringBB, Annotator);
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GPUNodeBuilder NodeBuilder(Builder, Annotator, this, *DL, *LI, *SE, *DT,
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*S);
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GPUNodeBuilder NodeBuilder(Builder, Annotator, this, *DL, *LI, *SE, *DT, *S,
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Prog);
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// Only build the run-time condition and parameters _after_ having
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// introduced the conditional branch. This is important as the conditional
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@ -741,7 +887,7 @@ public:
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auto PPCGGen = generateGPU(PPCGScop, PPCGProg);
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if (PPCGGen->tree)
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generateCode(isl_ast_node_copy(PPCGGen->tree));
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generateCode(isl_ast_node_copy(PPCGGen->tree), PPCGProg);
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freeOptions(PPCGScop);
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freePPCGGen(PPCGGen);
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@ -0,0 +1,76 @@
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; RUN: opt %loadPolly -polly-codegen-ppcg -polly-acc-dump-kernel-ir \
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; RUN: -disable-output < %s | \
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; RUN: FileCheck -check-prefix=KERNEL %s
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;
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; void kernel_params_only_some_arrays(float A[], float B[]) {
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; for (long i = 0; i < 32; i++)
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; A[i] += 42;
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;
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; for (long i = 0; i < 32; i++)
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; B[i] += 42;
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; }
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; KERNEL: ; ModuleID = 'kernel_0'
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; KERNEL-NEXT: source_filename = "kernel_0"
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; KERNEL-NEXT: target datalayout = "e-i64:64-v16:16-v32:32-n16:32:64"
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; KERNEL-NEXT: target triple = "nvptx64-nvidia-cuda"
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; KERNEL: define ptx_kernel void @kernel_0(i8* %MemRef_A) {
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; KERNEL-NEXT: entry:
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; KERNEL-NEXT: ret void
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; KERNEL-NEXT: }
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; KERNEL: ; ModuleID = 'kernel_1'
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; KERNEL-NEXT: source_filename = "kernel_1"
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; KERNEL-NEXT: target datalayout = "e-i64:64-v16:16-v32:32-n16:32:64"
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; KERNEL-NEXT: target triple = "nvptx64-nvidia-cuda"
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; KERNEL: define ptx_kernel void @kernel_1(i8* %MemRef_B) {
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; KERNEL-NEXT: entry:
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; KERNEL-NEXT: ret void
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; KERNEL-NEXT: }
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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define void @kernel_params_only_some_arrays(float* %A, float* %B) {
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entry:
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br label %for.cond
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for.cond: ; preds = %for.inc, %entry
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%i.0 = phi i64 [ 0, %entry ], [ %inc, %for.inc ]
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%exitcond1 = icmp ne i64 %i.0, 32
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br i1 %exitcond1, label %for.body, label %for.end
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for.body: ; preds = %for.cond
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%arrayidx = getelementptr inbounds float, float* %A, i64 %i.0
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%tmp = load float, float* %arrayidx, align 4
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%add = fadd float %tmp, 4.200000e+01
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store float %add, float* %arrayidx, align 4
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br label %for.inc
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for.inc: ; preds = %for.body
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%inc = add nuw nsw i64 %i.0, 1
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br label %for.cond
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for.end: ; preds = %for.cond
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br label %for.cond2
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for.cond2: ; preds = %for.inc7, %for.end
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%i1.0 = phi i64 [ 0, %for.end ], [ %inc8, %for.inc7 ]
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%exitcond = icmp ne i64 %i1.0, 32
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br i1 %exitcond, label %for.body4, label %for.end9
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for.body4: ; preds = %for.cond2
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%arrayidx5 = getelementptr inbounds float, float* %B, i64 %i1.0
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%tmp2 = load float, float* %arrayidx5, align 4
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%add6 = fadd float %tmp2, 4.200000e+01
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store float %add6, float* %arrayidx5, align 4
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br label %for.inc7
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for.inc7: ; preds = %for.body4
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%inc8 = add nuw nsw i64 %i1.0, 1
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br label %for.cond2
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for.end9: ; preds = %for.cond2
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ret void
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}
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