1 files changed, 122 insertions, 0 deletions
diff --git a/clang/lib/CodeGen/CGGPUBuiltin.cpp b/clang/lib/CodeGen/CGGPUBuiltin.cpp
new file mode 100644
index 000000000000..d7e267630762
--- /dev/null
+++ b/clang/lib/CodeGen/CGGPUBuiltin.cpp
@@ -0,0 +1,122 @@
+//===------ CGGPUBuiltin.cpp - Codegen for GPU builtins -------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Generates code for built-in GPU calls which are not runtime-specific.
+// (Runtime-specific codegen lives in programming model specific files.)
+//
+//===----------------------------------------------------------------------===//
+
+#include "CodeGenFunction.h"
+#include "clang/Basic/Builtins.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/Support/MathExtras.h"
+
+using namespace clang;
+using namespace CodeGen;
+
+static llvm::Function *GetVprintfDeclaration(llvm::Module &M) {
+  llvm::Type *ArgTypes[] = {llvm::Type::getInt8PtrTy(M.getContext()),
+                            llvm::Type::getInt8PtrTy(M.getContext())};
+  llvm::FunctionType *VprintfFuncType = llvm::FunctionType::get(
+      llvm::Type::getInt32Ty(M.getContext()), ArgTypes, false);
+
+  if (auto* F = M.getFunction("vprintf")) {
+    // Our CUDA system header declares vprintf with the right signature, so
+    // nobody else should have been able to declare vprintf with a bogus
+    // signature.
+    assert(F->getFunctionType() == VprintfFuncType);
+    return F;
+  }
+
+  // vprintf doesn't already exist; create a declaration and insert it into the
+  // module.
+  return llvm::Function::Create(
+      VprintfFuncType, llvm::GlobalVariable::ExternalLinkage, "vprintf", &M);
+}
+
+// Transforms a call to printf into a call to the NVPTX vprintf syscall (which
+// isn't particularly special; it's invoked just like a regular function).
+// vprintf takes two args: A format string, and a pointer to a buffer containing
+// the varargs.
+//
+// For example, the call
+//
+//   printf("format string", arg1, arg2, arg3);
+//
+// is converted into something resembling
+//
+//   struct Tmp {
+//     Arg1 a1;
+//     Arg2 a2;
+//     Arg3 a3;
+//   };
+//   char* buf = alloca(sizeof(Tmp));
+//   *(Tmp*)buf = {a1, a2, a3};
+//   vprintf("format string", buf);
+//
+// buf is aligned to the max of {alignof(Arg1), ...}.  Furthermore, each of the
+// args is itself aligned to its preferred alignment.
+//
+// Note that by the time this function runs, E's args have already undergone the
+// standard C vararg promotion (short -> int, float -> double, etc.).
+RValue
+CodeGenFunction::EmitNVPTXDevicePrintfCallExpr(const CallExpr *E,
+                                               ReturnValueSlot ReturnValue) {
+  assert(getTarget().getTriple().isNVPTX());
+  assert(E->getBuiltinCallee() == Builtin::BIprintf);
+  assert(E->getNumArgs() >= 1); // printf always has at least one arg.
+
+  const llvm::DataLayout &DL = CGM.getDataLayout();
+  llvm::LLVMContext &Ctx = CGM.getLLVMContext();
+
+  CallArgList Args;
+  EmitCallArgs(Args,
+               E->getDirectCallee()->getType()->getAs<FunctionProtoType>(),
+               E->arguments(), E->getDirectCallee(),
+               /* ParamsToSkip = */ 0);
+
+  // We don't know how to emit non-scalar varargs.
+  if (std::any_of(Args.begin() + 1, Args.end(), [&](const CallArg &A) {
+        return !A.getRValue(*this).isScalar();
+      })) {
+    CGM.ErrorUnsupported(E, "non-scalar arg to printf");
+    return RValue::get(llvm::ConstantInt::get(IntTy, 0));
+  }
+
+  // Construct and fill the args buffer that we'll pass to vprintf.
+  llvm::Value *BufferPtr;
+  if (Args.size() <= 1) {
+    // If there are no args, pass a null pointer to vprintf.
+    BufferPtr = llvm::ConstantPointerNull::get(llvm::Type::getInt8PtrTy(Ctx));
+  } else {
+    llvm::SmallVector<llvm::Type *, 8> ArgTypes;
+    for (unsigned I = 1, NumArgs = Args.size(); I < NumArgs; ++I)
+      ArgTypes.push_back(Args[I].getRValue(*this).getScalarVal()->getType());
+
+    // Using llvm::StructType is correct only because printf doesn't accept
+    // aggregates.  If we had to handle aggregates here, we'd have to manually
+    // compute the offsets within the alloca -- we wouldn't be able to assume
+    // that the alignment of the llvm type was the same as the alignment of the
+    // clang type.
+    llvm::Type *AllocaTy = llvm::StructType::create(ArgTypes, "printf_args");
+    llvm::Value *Alloca = CreateTempAlloca(AllocaTy);
+
+    for (unsigned I = 1, NumArgs = Args.size(); I < NumArgs; ++I) {
+      llvm::Value *P = Builder.CreateStructGEP(AllocaTy, Alloca, I - 1);
+      llvm::Value *Arg = Args[I].getRValue(*this).getScalarVal();
+      Builder.CreateAlignedStore(Arg, P, DL.getPrefTypeAlignment(Arg->getType()));
+    }
+    BufferPtr = Builder.CreatePointerCast(Alloca, llvm::Type::getInt8PtrTy(Ctx));
+  }
+
+  // Invoke vprintf and return.
+  llvm::Function* VprintfFunc = GetVprintfDeclaration(CGM.getModule());
+  return RValue::get(Builder.CreateCall(
+      VprintfFunc, {Args[0].getRValue(*this).getScalarVal(), BufferPtr}));
+}