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//===-- PPCGenScalarMASSEntries.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 transformation converts standard math functions into their
// corresponding MASS (scalar) entries for PowerPC targets.
// Following are examples of such conversion:
// tanh ---> __xl_tanh_finite
// Such lowering is legal under the fast-math option.
//
//===----------------------------------------------------------------------===//
#include "PPC.h"
#include "PPCSubtarget.h"
#include "PPCTargetMachine.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-gen-scalar-mass"
using namespace llvm;
namespace {
class PPCGenScalarMASSEntries : public ModulePass {
public:
static char ID;
PPCGenScalarMASSEntries() : ModulePass(ID) {
ScalarMASSFuncs = {
#define TLI_DEFINE_SCALAR_MASS_FUNCS
#include "llvm/Analysis/ScalarFuncs.def"
};
}
bool runOnModule(Module &M) override;
StringRef getPassName() const override {
return "PPC Generate Scalar MASS Entries";
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<TargetTransformInfoWrapperPass>();
}
private:
std::map<StringRef, StringRef> ScalarMASSFuncs;
bool isCandidateSafeToLower(const CallInst &CI) const;
bool isFiniteCallSafe(const CallInst &CI) const;
bool createScalarMASSCall(StringRef MASSEntry, CallInst &CI,
Function &Func) const;
};
} // namespace
// Returns true if 'afn' flag exists on the call instruction with the math
// function
bool PPCGenScalarMASSEntries::isCandidateSafeToLower(const CallInst &CI) const {
// skip functions with no scalar or vector FP type (like cosisin)
if (!isa<FPMathOperator>(CI))
return false;
return CI.hasApproxFunc();
}
// Returns true if 'nnan', 'ninf' and 'nsz' flags exist on the call instruction
// with the math function
bool PPCGenScalarMASSEntries::isFiniteCallSafe(const CallInst &CI) const {
// skip functions with no scalar or vector FP type (like cosisin)
if (!isa<FPMathOperator>(CI))
return false;
// FIXME: no-errno and trapping-math need to be set for MASS converstion
// but they don't have IR representation.
return CI.hasNoNaNs() && CI.hasNoInfs() && CI.hasNoSignedZeros();
}
/// Lowers scalar math functions to scalar MASS functions.
/// e.g.: tanh --> __xl_tanh_finite or __xl_tanh
/// Both function prototype and its callsite is updated during lowering.
bool PPCGenScalarMASSEntries::createScalarMASSCall(StringRef MASSEntry,
CallInst &CI,
Function &Func) const {
if (CI.use_empty())
return false;
Module *M = Func.getParent();
assert(M && "Expecting a valid Module");
std::string MASSEntryStr = MASSEntry.str();
if (isFiniteCallSafe(CI))
MASSEntryStr += "_finite";
FunctionCallee FCache = M->getOrInsertFunction(
MASSEntryStr, Func.getFunctionType(), Func.getAttributes());
CI.setCalledFunction(FCache);
return true;
}
bool PPCGenScalarMASSEntries::runOnModule(Module &M) {
bool Changed = false;
auto *TPC = getAnalysisIfAvailable<TargetPassConfig>();
if (!TPC || skipModule(M))
return false;
for (Function &Func : M) {
if (!Func.isDeclaration())
continue;
auto Iter = ScalarMASSFuncs.find(Func.getName());
if (Iter == ScalarMASSFuncs.end())
continue;
// The call to createScalarMASSCall() 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> TheUsers;
for (auto *User : Func.users())
TheUsers.push_back(User);
for (auto *User : TheUsers)
if (auto *CI = dyn_cast_or_null<CallInst>(User)) {
if (isCandidateSafeToLower(*CI))
Changed |= createScalarMASSCall(Iter->second, *CI, Func);
}
}
return Changed;
}
char PPCGenScalarMASSEntries::ID = 0;
char &llvm::PPCGenScalarMASSEntriesID = PPCGenScalarMASSEntries::ID;
INITIALIZE_PASS(PPCGenScalarMASSEntries, DEBUG_TYPE,
"Generate Scalar MASS entries", false, false)
ModulePass *llvm::createPPCGenScalarMASSEntriesPass() {
return new PPCGenScalarMASSEntries();
}
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