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//===-- PPCLowerMASSVEntries.cpp ------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements lowering of MASSV (SIMD) entries for specific PowerPC
// subtargets.
// Following is an example of a conversion specific to Power9 subtarget:
// __sind2_massv ---> __sind2_P9
//
//===----------------------------------------------------------------------===//
#include "PPC.h"
#include "PPCSubtarget.h"
#include "PPCTargetMachine.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Module.h"
#define DEBUG_TYPE "ppc-lower-massv-entries"
using namespace llvm;
namespace {
static StringRef MASSVFuncs[] = {
#define TLI_DEFINE_MASSV_VECFUNCS_NAMES
#include "llvm/Analysis/VecFuncs.def"
};
class PPCLowerMASSVEntries : public ModulePass {
public:
static char ID;
PPCLowerMASSVEntries() : ModulePass(ID) {}
bool runOnModule(Module &M) override;
StringRef getPassName() const override { return "PPC Lower MASS Entries"; }
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<TargetTransformInfoWrapperPass>();
}
private:
static bool isMASSVFunc(StringRef Name);
static StringRef getCPUSuffix(const PPCSubtarget *Subtarget);
static std::string createMASSVFuncName(Function &Func,
const PPCSubtarget *Subtarget);
bool handlePowSpecialCases(CallInst *CI, Function &Func, Module &M);
bool lowerMASSVCall(CallInst *CI, Function &Func, Module &M,
const PPCSubtarget *Subtarget);
};
} // namespace
/// Checks if the specified function name represents an entry in the MASSV
/// library.
bool PPCLowerMASSVEntries::isMASSVFunc(StringRef Name) {
return llvm::is_contained(MASSVFuncs, Name);
}
// FIXME:
/// Returns a string corresponding to the specified PowerPC subtarget. e.g.:
/// "_P8" for Power8, "_P9" for Power9. The string is used as a suffix while
/// generating subtarget-specific MASSV library functions. Current support
/// includes minimum subtarget Power8 for Linux and Power7 for AIX.
StringRef PPCLowerMASSVEntries::getCPUSuffix(const PPCSubtarget *Subtarget) {
// Assume generic when Subtarget is unavailable.
if (!Subtarget)
return "";
// TODO: add _P10 enties to Linux MASS lib and remove the check for AIX
if (Subtarget->isAIXABI() && Subtarget->hasP10Vector())
return "_P10";
if (Subtarget->hasP9Vector())
return "_P9";
if (Subtarget->hasP8Vector())
return "_P8";
if (Subtarget->isAIXABI())
return "_P7";
report_fatal_error(
"Mininum subtarget for -vector-library=MASSV option is Power8 on Linux "
"and Power7 on AIX when vectorization is not disabled.");
}
/// Creates PowerPC subtarget-specific name corresponding to the specified
/// generic MASSV function, and the PowerPC subtarget.
std::string
PPCLowerMASSVEntries::createMASSVFuncName(Function &Func,
const PPCSubtarget *Subtarget) {
StringRef Suffix = getCPUSuffix(Subtarget);
auto GenericName = Func.getName().str();
std::string MASSVEntryName = GenericName + Suffix.str();
return MASSVEntryName;
}
/// If there are proper fast-math flags, this function creates llvm.pow
/// intrinsics when the exponent is 0.25 or 0.75.
bool PPCLowerMASSVEntries::handlePowSpecialCases(CallInst *CI, Function &Func,
Module &M) {
if (Func.getName() != "__powf4" && Func.getName() != "__powd2")
return false;
if (Constant *Exp = dyn_cast<Constant>(CI->getArgOperand(1)))
if (ConstantFP *CFP = dyn_cast_or_null<ConstantFP>(Exp->getSplatValue())) {
// If the argument is 0.75 or 0.25 it is cheaper to turn it into pow
// intrinsic so that it could be optimzed as sequence of sqrt's.
if (!CI->hasNoInfs() || !CI->hasApproxFunc())
return false;
if (!CFP->isExactlyValue(0.75) && !CFP->isExactlyValue(0.25))
return false;
if (CFP->isExactlyValue(0.25) && !CI->hasNoSignedZeros())
return false;
CI->setCalledFunction(
Intrinsic::getDeclaration(&M, Intrinsic::pow, CI->getType()));
return true;
}
return false;
}
/// Lowers generic MASSV entries to PowerPC subtarget-specific MASSV entries.
/// e.g.: __sind2_massv --> __sind2_P9 for a Power9 subtarget.
/// Both function prototypes and their callsites are updated during lowering.
bool PPCLowerMASSVEntries::lowerMASSVCall(CallInst *CI, Function &Func,
Module &M,
const PPCSubtarget *Subtarget) {
if (CI->use_empty())
return false;
// Handling pow(x, 0.25), pow(x, 0.75), powf(x, 0.25), powf(x, 0.75)
if (handlePowSpecialCases(CI, Func, M))
return true;
std::string MASSVEntryName = createMASSVFuncName(Func, Subtarget);
FunctionCallee FCache = M.getOrInsertFunction(
MASSVEntryName, Func.getFunctionType(), Func.getAttributes());
CI->setCalledFunction(FCache);
return true;
}
bool PPCLowerMASSVEntries::runOnModule(Module &M) {
bool Changed = false;
auto *TPC = getAnalysisIfAvailable<TargetPassConfig>();
if (!TPC)
return Changed;
auto &TM = TPC->getTM<PPCTargetMachine>();
const PPCSubtarget *Subtarget;
for (Function &Func : M) {
if (!Func.isDeclaration())
continue;
if (!isMASSVFunc(Func.getName()))
continue;
// Call to lowerMASSVCall() invalidates the iterator over users upon
// replacing the users. Precomputing the current list of users allows us to
// replace all the call sites.
SmallVector<User *, 4> MASSVUsers(Func.users());
for (auto *User : MASSVUsers) {
auto *CI = dyn_cast<CallInst>(User);
if (!CI)
continue;
Subtarget = &TM.getSubtarget<PPCSubtarget>(*CI->getParent()->getParent());
Changed |= lowerMASSVCall(CI, Func, M, Subtarget);
}
}
return Changed;
}
char PPCLowerMASSVEntries::ID = 0;
char &llvm::PPCLowerMASSVEntriesID = PPCLowerMASSVEntries::ID;
INITIALIZE_PASS(PPCLowerMASSVEntries, DEBUG_TYPE, "Lower MASSV entries", false,
false)
ModulePass *llvm::createPPCLowerMASSVEntriesPass() {
return new PPCLowerMASSVEntries();
}
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