[llvm] r178416 - [NVPTX] Add NVVMReflect pass to allow compile-time selection of
Justin Holewinski
jholewinski at nvidia.com
Sat Mar 30 07:29:25 PDT 2013
Author: jholewinski
Date: Sat Mar 30 09:29:25 2013
New Revision: 178416
URL: http://llvm.org/viewvc/llvm-project?rev=178416&view=rev
Log:
[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.
Added:
llvm/trunk/lib/Target/NVPTX/NVVMReflect.cpp
llvm/trunk/test/CodeGen/NVPTX/nvvm-reflect.ll
Modified:
llvm/trunk/lib/Target/NVPTX/CMakeLists.txt
llvm/trunk/lib/Target/NVPTX/NVPTXTargetMachine.cpp
Modified: llvm/trunk/lib/Target/NVPTX/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/NVPTX/CMakeLists.txt?rev=178416&r1=178415&r2=178416&view=diff
==============================================================================
--- llvm/trunk/lib/Target/NVPTX/CMakeLists.txt (original)
+++ llvm/trunk/lib/Target/NVPTX/CMakeLists.txt Sat Mar 30 09:29:25 2013
@@ -22,6 +22,7 @@ set(NVPTXCodeGen_sources
NVPTXAllocaHoisting.cpp
NVPTXAsmPrinter.cpp
NVPTXUtilities.cpp
+ NVVMReflect.cpp
)
add_llvm_target(NVPTXCodeGen ${NVPTXCodeGen_sources})
Modified: llvm/trunk/lib/Target/NVPTX/NVPTXTargetMachine.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/NVPTX/NVPTXTargetMachine.cpp?rev=178416&r1=178415&r2=178416&view=diff
==============================================================================
--- llvm/trunk/lib/Target/NVPTX/NVPTXTargetMachine.cpp (original)
+++ llvm/trunk/lib/Target/NVPTX/NVPTXTargetMachine.cpp Sat Mar 30 09:29:25 2013
@@ -47,6 +47,10 @@
using namespace llvm;
+namespace llvm {
+void initializeNVVMReflectPass(PassRegistry&);
+}
+
extern "C" void LLVMInitializeNVPTXTarget() {
// Register the target.
RegisterTargetMachine<NVPTXTargetMachine32> X(TheNVPTXTarget32);
@@ -55,6 +59,9 @@ extern "C" void LLVMInitializeNVPTXTarge
RegisterMCAsmInfo<NVPTXMCAsmInfo> A(TheNVPTXTarget32);
RegisterMCAsmInfo<NVPTXMCAsmInfo> B(TheNVPTXTarget64);
+ // FIXME: This pass is really intended to be invoked during IR optimization,
+ // but it's very NVPTX-specific.
+ initializeNVVMReflectPass(*PassRegistry::getPassRegistry());
}
NVPTXTargetMachine::NVPTXTargetMachine(
Added: llvm/trunk/lib/Target/NVPTX/NVVMReflect.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/NVPTX/NVVMReflect.cpp?rev=178416&view=auto
==============================================================================
--- llvm/trunk/lib/Target/NVPTX/NVVMReflect.cpp (added)
+++ llvm/trunk/lib/Target/NVPTX/NVVMReflect.cpp Sat Mar 30 09:29:25 2013
@@ -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;
+}
Added: llvm/trunk/test/CodeGen/NVPTX/nvvm-reflect.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/NVPTX/nvvm-reflect.ll?rev=178416&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/NVPTX/nvvm-reflect.ll (added)
+++ llvm/trunk/test/CodeGen/NVPTX/nvvm-reflect.ll Sat Mar 30 09:29:25 2013
@@ -0,0 +1,34 @@
+; RUN: opt < %s -S -nvvm-reflect -nvvm-reflect-list USE_MUL=0 -O2 | FileCheck %s --check-prefix=USE_MUL_0
+; RUN: opt < %s -S -nvvm-reflect -nvvm-reflect-list USE_MUL=1 -O2 | FileCheck %s --check-prefix=USE_MUL_1
+
+ at str = private addrspace(4) unnamed_addr constant [8 x i8] c"USE_MUL\00"
+
+declare i32 @__nvvm_reflect(i8*)
+declare i8* @llvm.nvvm.ptr.constant.to.gen.p0i8.p4i8(i8 addrspace(4)*)
+
+define float @foo(float %a, float %b) {
+; USE_MUL_0: define float @foo
+; USE_MUL_0-NOT: call i32 @__nvvm_reflect
+; USE_MUL_1: define float @foo
+; USE_MUL_1-NOT: call i32 @__nvvm_reflect
+ %ptr = tail call i8* @llvm.nvvm.ptr.constant.to.gen.p0i8.p4i8(i8 addrspace(4)* getelementptr inbounds ([8 x i8] addrspace(4)* @str, i32 0, i32 0))
+ %reflect = tail call i32 @__nvvm_reflect(i8* %ptr)
+ %cmp = icmp ugt i32 %reflect, 0
+ br i1 %cmp, label %use_mul, label %use_add
+
+use_mul:
+; USE_MUL_1: fmul float %a, %b
+; USE_MUL_0-NOT: fadd float %a, %b
+ %ret1 = fmul float %a, %b
+ br label %exit
+
+use_add:
+; USE_MUL_0: fadd float %a, %b
+; USE_MUL_1-NOT: fmul float %a, %b
+ %ret2 = fadd float %a, %b
+ br label %exit
+
+exit:
+ %ret = phi float [%ret1, %use_mul], [%ret2, %use_add]
+ ret float %ret
+}
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