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Add support for CUDA __launch_bounds__ attribute to CodeGen. 

Sema does have a CUDALaunchBoundsAttr, but CodeGen was doing nothing with it.
This change translates CUDALaunchBoundsAttr to maxntidx and minctasm
metadata, which NVPTX then translates to the correct PTX directives.

Patch by Manjunath Kudlur.

llvm-svn: 206302
This commit is contained in:
Eli Bendersky 2014-04-15 16:57:05 +00:00
parent 52eaffee03
commit e06a2c4f90
1 changed files with 28 additions and 10 deletions
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38
clang/lib/CodeGen/TargetInfo.cpp
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@ -4770,7 +4770,9 @@ public:
void SetTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
CodeGen::CodeGenModule &M) const override;
private:
static void addKernelMetadata(llvm::Function *F);
// Adds a NamedMDNode with F, Name, and Operand as operands, and adds the
// resulting MDNode to the nvvm.annotations MDNode.
static void addNVVMMetadata(llvm::Function *F, StringRef Name, int Operand);
};
ABIArgInfo NVPTXABIInfo::classifyReturnType(QualType RetTy) const {
@ -4829,7 +4831,8 @@ SetTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
// By default, all functions are device functions
if (FD->hasAttr<OpenCLKernelAttr>()) {
// OpenCL __kernel functions get kernel metadata
addKernelMetadata(F);
// Create !{<func-ref>, metadata !"kernel", i32 1} node
addNVVMMetadata(F, "kernel", 1);
// And kernel functions are not subject to inlining
F->addFnAttr(llvm::Attribute::NoInline);
}
@ -4840,28 +4843,43 @@ SetTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
// CUDA __global__ functions get a kernel metadata entry. Since
// __global__ functions cannot be called from the device, we do not
// need to set the noinline attribute.
if (FD->hasAttr<CUDAGlobalAttr>())
addKernelMetadata(F);
if (FD->hasAttr<CUDAGlobalAttr>()) {
// Create !{<func-ref>, metadata !"kernel", i32 1} node
addNVVMMetadata(F, "kernel", 1);
}
if (FD->hasAttr<CUDALaunchBoundsAttr>()) {
// Create !{<func-ref>, metadata !"maxntidx", i32 <val>} node
addNVVMMetadata(F, "maxntidx",
FD->getAttr<CUDALaunchBoundsAttr>()->getMaxThreads());
// min blocks is a default argument for CUDALaunchBoundsAttr, so getting a
// zero value from getMinBlocks either means it was not specified in
// __launch_bounds__ or the user specified a 0 value. In both cases, we
// don't have to add a PTX directive.
int MinCTASM = FD->getAttr<CUDALaunchBoundsAttr>()->getMinBlocks();
if (MinCTASM > 0) {
// Create !{<func-ref>, metadata !"minctasm", i32 <val>} node
addNVVMMetadata(F, "minctasm", MinCTASM);
}
}
}
}
void NVPTXTargetCodeGenInfo::addKernelMetadata(llvm::Function *F) {
void NVPTXTargetCodeGenInfo::addNVVMMetadata(llvm::Function *F, StringRef Name,
int Operand) {
llvm::Module *M = F->getParent();
llvm::LLVMContext &Ctx = M->getContext();
// Get "nvvm.annotations" metadata node
llvm::NamedMDNode *MD = M->getOrInsertNamedMetadata("nvvm.annotations");
// Create !{<func-ref>, metadata !"kernel", i32 1} node
llvm::SmallVector<llvm::Value *, 3> MDVals;
MDVals.push_back(F);
MDVals.push_back(llvm::MDString::get(Ctx, "kernel"));
MDVals.push_back(llvm::ConstantInt::get(llvm::Type::getInt32Ty(Ctx), 1));
MDVals.push_back(llvm::MDString::get(Ctx, Name));
MDVals.push_back(
llvm::ConstantInt::get(llvm::Type::getInt32Ty(Ctx), Operand));
// Append metadata to nvvm.annotations
MD->addOperand(llvm::MDNode::get(Ctx, MDVals));
}
}
//===----------------------------------------------------------------------===//