[NVPTX] Add NVVMReflect pass to allow compile-time selection of
specific code paths.
This allows us to write code like:
if (__nvvm_reflect("FOO"))
// Do something
else
// Do something else
and compile into a library, then give "FOO" a value at kernel
compile-time so the check becomes a no-op.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178416 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/NVPTX/NVVMReflect.cpp b/lib/Target/NVPTX/NVVMReflect.cpp
new file mode 100644
index 0000000..3bbd1a1
--- /dev/null
+++ b/lib/Target/NVPTX/NVVMReflect.cpp
@@ -0,0 +1,193 @@
+//===- NVVMReflect.cpp - NVVM Emulate conditional compilation -------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass replaces occurences of __nvvm_reflect("string") with an
+// integer based on -nvvm-reflect-list string=<int> option given to this pass.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/StringMap.h"
+#include "llvm/Pass.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Type.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_os_ostream.h"
+#include "llvm/Transforms/Scalar.h"
+#include <map>
+#include <sstream>
+#include <string>
+#include <vector>
+
+#define NVVM_REFLECT_FUNCTION "__nvvm_reflect"
+
+using namespace llvm;
+
+namespace llvm { void initializeNVVMReflectPass(PassRegistry &); }
+
+namespace {
+class LLVM_LIBRARY_VISIBILITY NVVMReflect : public ModulePass {
+private:
+ //std::map<std::string, int> VarMap;
+ StringMap<int> VarMap;
+ typedef std::map<std::string, int>::iterator VarMapIter;
+ Function *reflectFunction;
+
+public:
+ static char ID;
+ NVVMReflect() : ModulePass(ID) {
+ VarMap.clear();
+ reflectFunction = 0;
+ }
+
+ void getAnalysisUsage(AnalysisUsage &AU) const { AU.setPreservesAll(); }
+ virtual bool runOnModule(Module &);
+
+ void setVarMap();
+};
+}
+
+static cl::opt<bool>
+NVVMReflectEnabled("nvvm-reflect-enable", cl::init(true),
+ cl::desc("NVVM reflection, enabled by default"));
+
+char NVVMReflect::ID = 0;
+INITIALIZE_PASS(NVVMReflect, "nvvm-reflect",
+ "Replace occurences of __nvvm_reflect() calls with 0/1", false,
+ false)
+
+static cl::list<std::string>
+ReflectList("nvvm-reflect-list", cl::value_desc("name=0/1"),
+ cl::desc("A list of string=num assignments, where num=0 or 1"),
+ cl::ValueRequired);
+
+/// This function does the same operation as perl's split.
+/// For example, calling this with ("a=1,b=2,c=0", ",") will
+/// return ["a=1", "b=2", "c=0"] in the return std::vector.
+static std::vector<std::string>
+Tokenize(const std::string &str, const std::string &delim) {
+ std::vector<std::string> tokens;
+
+ size_t p0 = 0, p1 = std::string::npos;
+ while (p0 != std::string::npos) {
+ p1 = str.find_first_of(delim, p0);
+ if (p1 != p0) {
+ std::string token = str.substr(p0, p1 - p0);
+ tokens.push_back(token);
+ }
+ p0 = str.find_first_not_of(delim, p1);
+ }
+
+ return tokens;
+}
+
+/// The command line can look as follows :
+/// -R a=1,b=2 -R c=3,d=0 -R e=2
+/// The strings "a=1,b=2", "c=3,d=0", "e=2" are available in the
+/// ReflectList vector. First, each of ReflectList[i] is 'split'
+/// using "," as the delimiter. Then each of this part is split
+/// using "=" as the delimiter.
+void NVVMReflect::setVarMap() {
+ for (unsigned i = 0, e = ReflectList.size(); i != e; ++i) {
+ // DEBUG(dbgs() << "Option : " << ReflectList[i] << std::endl);
+ std::vector<std::string> nameValList = Tokenize(ReflectList[i], ",");
+ for (unsigned j = 0, ej = nameValList.size(); j != ej; ++j) {
+ std::vector<std::string> nameValPair = Tokenize(nameValList[j], "=");
+ assert(nameValPair.size() == 2 && "name=val expected");
+ std::stringstream valstream(nameValPair[1]);
+ int val;
+ valstream >> val;
+ assert((!(valstream.fail())) && "integer value expected");
+ VarMap[nameValPair[0]] = val;
+ }
+ }
+}
+
+bool NVVMReflect::runOnModule(Module &M) {
+ if (!NVVMReflectEnabled)
+ return false;
+
+ setVarMap();
+
+ reflectFunction = M.getFunction(NVVM_REFLECT_FUNCTION);
+
+ // If reflect function is not used, then there will be
+ // no entry in the module.
+ if (reflectFunction == 0) {
+ return false;
+ }
+
+ // Validate _reflect function
+ assert(reflectFunction->isDeclaration() &&
+ "_reflect function should not have a body");
+ assert(reflectFunction->getReturnType()->isIntegerTy() &&
+ "_reflect's return type should be integer");
+
+ std::vector<Instruction *> toRemove;
+
+ // Go through the uses of reflectFunction in this Function.
+ // Each of them should a CallInst with a ConstantArray argument.
+ // First validate that. If the c-string corresponding to the
+ // ConstantArray can be found successfully, see if it can be
+ // found in VarMap. If so, replace the uses of CallInst with the
+ // value found in VarMap. If not, replace the use with value 0.
+ for (Value::use_iterator iter = reflectFunction->use_begin(),
+ iterEnd = reflectFunction->use_end();
+ iter != iterEnd; ++iter) {
+ assert(isa<CallInst>(*iter) && "Only a call instruction can use _reflect");
+ CallInst *reflect = cast<CallInst>(*iter);
+
+ assert((reflect->getNumOperands() == 2) &&
+ "Only one operand expect for _reflect function");
+ // In cuda, we will have an extra constant-to-generic conversion of
+ // the string.
+ const Value *conv = reflect->getArgOperand(0);
+ assert(isa<CallInst>(conv) && "Expected a const-to-gen conversion");
+ const CallInst *convcall = cast<CallInst>(conv);
+ const Value *str = convcall->getArgOperand(0);
+ assert(isa<ConstantExpr>(str) &&
+ "Format of _reflect function not recognized");
+ const ConstantExpr *gep = cast<ConstantExpr>(str);
+
+ const Value *sym = gep->getOperand(0);
+ assert(isa<Constant>(sym) && "Format of _reflect function not recognized");
+
+ const Constant *symstr = cast<Constant>(sym);
+
+ assert(isa<ConstantDataSequential>(symstr->getOperand(0)) &&
+ "Format of _reflect function not recognized");
+
+ assert(cast<ConstantDataSequential>(symstr->getOperand(0))->isCString() &&
+ "Format of _reflect function not recognized");
+
+ std::string reflectArg =
+ cast<ConstantDataSequential>(symstr->getOperand(0))->getAsString();
+
+ reflectArg = reflectArg.substr(0, reflectArg.size() - 1);
+ // DEBUG(dbgs() << "Arg of _reflect : " << reflectArg << std::endl);
+
+ int reflectVal = 0; // The default value is 0
+ if (VarMap.find(reflectArg) != VarMap.end()) {
+ reflectVal = VarMap[reflectArg];
+ }
+ reflect->replaceAllUsesWith(
+ ConstantInt::get(reflect->getType(), reflectVal));
+ toRemove.push_back(reflect);
+ }
+ if (toRemove.size() == 0)
+ return false;
+
+ for (unsigned i = 0, e = toRemove.size(); i != e; ++i)
+ toRemove[i]->eraseFromParent();
+ return true;
+}