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/*========================== begin_copyright_notice ============================
Copyright (C) 2017-2021 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
//
/// GenXLiveRanges
/// --------------
///
/// GenXLiveRanges calculates the actual live range information (the segments)
/// on the LiveRange object for each value. See the comment at the top of
/// GenXLiveness.h for details of how the live range information works. This
/// pass calls GenXLiveness::buildLiveRange to do the work for each value.
///
/// The LiveRange object for each value already existed before this pass, as it
/// was created by GenXCategory. In the case of a value that we can now see does
/// not want a LiveRange, because it is an Instruction baled in to something,
/// we erase the LiveRange here.
///
//===----------------------------------------------------------------------===//
#include "FunctionGroup.h"
#include "GenX.h"
#include "GenXBaling.h"
#include "GenXIntrinsics.h"
#include "GenXLiveness.h"
#include "GenXNumbering.h"
#include "vc/Support/BackendConfig.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/Debug.h"
#include "Probe/Assertion.h"
#define DEBUG_TYPE "GENX_LIVERANGES"
using namespace llvm;
using namespace genx;
namespace {
class GenXLiveRanges : public FGPassImplInterface,
public IDMixin<GenXLiveRanges> {
FunctionGroup *FG = nullptr;
GenXBaling *Baling = nullptr;
GenXLiveness *Liveness = nullptr;
public:
explicit GenXLiveRanges() {}
static StringRef getPassName() { return "GenX live ranges analysis"; }
static void getAnalysisUsage(AnalysisUsage &AU);
bool runOnFunctionGroup(FunctionGroup &FG) override;
private:
void buildLiveRanges();
bool isPredefinedVariable(Value *) const;
};
/***********************************************************************
* Local function for testing one assertion statement.
* Check we don't have any leftover empty live ranges. If we do, it means
* that a pass between GenXCategory and here has erased a value and failed
* to erase its LiveRange, or alternatively this pass has failed to erase
* the LiveRange for a value that does not need it because it is a baled
* in instruction.
*/
bool testDuplicates(/*const*/ llvm::GenXLiveness& Liveness) {
if (std::any_of(Liveness.begin(), Liveness.end(),
[](const auto &X) { return X.second == nullptr; })) {
llvm::errs() << "Liveness contains NULL live ranges\n";
return false;
}
auto testRange = [](const auto &X) {
auto HasSegment = (X.second->size() > 0);
auto UndefVal = isa<UndefValue>(X.first.getValue());
return !(HasSegment || UndefVal);
};
auto WrongLR = std::find_if(Liveness.begin(), Liveness.end(), testRange);
if (WrongLR != Liveness.end()) {
llvm::errs() << "Bad live range\n";
WrongLR->second->print(llvm::errs(), true);
llvm::errs() << "\nWhole liveness:\n";
Liveness.dump();
llvm::errs() << "\n";
return false;
}
return true;
}
} // end anonymous namespace
namespace llvm {
void initializeGenXLiveRangesWrapperPass(PassRegistry &);
using GenXLiveRangesWrapper = FunctionGroupWrapperPass<GenXLiveRanges>;
} // namespace llvm
INITIALIZE_PASS_BEGIN(GenXLiveRangesWrapper, "GenXLiveRangesWrapper",
"GenXLiveRangesWrapper", false, false)
INITIALIZE_PASS_DEPENDENCY(GenXGroupBalingWrapper)
INITIALIZE_PASS_DEPENDENCY(GenXLivenessWrapper)
INITIALIZE_PASS_DEPENDENCY(GenXNumberingWrapper)
INITIALIZE_PASS_DEPENDENCY(FunctionGroupAnalysis)
INITIALIZE_PASS_END(GenXLiveRangesWrapper, "GenXLiveRangesWrapper",
"GenXLiveRangesWrapper", false, false)
ModulePass *llvm::createGenXLiveRangesWrapperPass() {
initializeGenXLiveRangesWrapperPass(*PassRegistry::getPassRegistry());
return new GenXLiveRangesWrapper();
}
void GenXLiveRanges::getAnalysisUsage(AnalysisUsage &AU) {
AU.addRequired<GenXGroupBaling>();
AU.addRequired<GenXLiveness>();
AU.addRequired<GenXNumbering>();
AU.addRequired<GenXBackendConfig>();
AU.addRequired<FunctionGroupAnalysis>();
AU.setPreservesAll();
}
/***********************************************************************
* runOnFunctionGroup : run the liveness analysis for this FunctionGroup
*/
bool GenXLiveRanges::runOnFunctionGroup(FunctionGroup &ArgFG)
{
FG = &ArgFG;
const auto &BC = getAnalysis<GenXBackendConfig>();
Baling = &getAnalysis<GenXGroupBaling>();
Liveness = &getAnalysis<GenXLiveness>();
Liveness->setNoCoalescingMode(BC.disableLiveRangesCoalescing());
Liveness->setBaling(Baling);
Liveness->setNumbering(&getAnalysis<GenXNumbering>());
// Build the live ranges.
Liveness->buildSubroutineLRs();
buildLiveRanges();
IGC_ASSERT(testDuplicates(*Liveness));
return false;
}
/***********************************************************************
* isPredefinedVariable : check if it's tranlated into predefined
* variables in vISA.
*/
bool GenXLiveRanges::isPredefinedVariable(Value *V) const {
switch (GenXIntrinsic::getGenXIntrinsicID(V)) {
case GenXIntrinsic::genx_predefined_surface:
case GenXIntrinsic::genx_read_predef_reg:
case GenXIntrinsic::genx_write_predef_reg:
return true;
default:
break;
}
return false;
}
/***********************************************************************
* buildLiveRanges : build live ranges for all args and instructions
*/
void GenXLiveRanges::buildLiveRanges()
{
// Build live ranges for global variables;
for (auto &G : FG->getModule()->globals())
Liveness->buildLiveRange(&G);
for (auto i = FG->begin(), e = FG->end(); i != e; ++i) {
Function *Func = *i;
// Build live ranges for args.
for (auto fi = Func->arg_begin(), fe = Func->arg_end(); fi != fe; ++fi)
Liveness->buildLiveRange(&*fi);
if (!Func->getReturnType()->isVoidTy()) {
// Build live range(s) for unified return value.
Liveness->buildLiveRange(Liveness->getUnifiedRet(Func));
}
// Build live ranges for code.
for (Function::iterator fi = Func->begin(), fe = Func->end(); fi != fe; ++fi) {
BasicBlock *BB = &*fi;
for (BasicBlock::iterator bi = BB->begin(), be = BB->end(); bi != be; ++bi) {
Instruction *Inst = &*bi;
// Skip building live range for instructions
// - has no destination
// - is already baled, or
// - is predefined variable in vISA.
if (!Inst->getType()->isVoidTy() && !Baling->isBaled(Inst) &&
!isPredefinedVariable(Inst)) {
// Instruction is not baled in to anything.
// First check if the result is unused and it is an intrinsic whose
// result is marked RAW_NULLALLOWED. If so, don't create a live range,
// so no register gets allocated.
if (Inst->use_empty()) {
unsigned IID = vc::getAnyIntrinsicID(Inst);
switch (IID) {
case GenXIntrinsic::not_any_intrinsic:
case GenXIntrinsic::genx_rdregioni:
case GenXIntrinsic::genx_rdregionf:
case GenXIntrinsic::genx_wrregioni:
case GenXIntrinsic::genx_wrregionf:
case GenXIntrinsic::genx_wrconstregion:
break;
default: {
GenXIntrinsicInfo::ArgInfo AI
= GenXIntrinsicInfo(IID).getRetInfo();
if (AI.isRaw() && AI.rawNullAllowed()) {
// Unused RAW_NULLALLOWED result.
Liveness->eraseLiveRange(Inst);
continue;
}
break;
}
}
}
// Build its live range.
Liveness->buildLiveRange(Inst);
} else {
// Instruction is baled in to something. Erase its live range so the
// register allocator does not try and allocate it something.
Liveness->eraseLiveRange(Inst);
}
}
}
}
}
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