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//===- InjectTLIMAppings.cpp - TLI to VFABI attribute injection ----------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Populates the VFABI attribute with the scalar-to-vector mappings
// from the TargetLibraryInfo.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/InjectTLIMappings.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/DemandedBits.h"
#include "llvm/Analysis/GlobalsModRef.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/VFABIDemangler.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
using namespace llvm;
#define DEBUG_TYPE "inject-tli-mappings"
STATISTIC(NumCallInjected,
"Number of calls in which the mappings have been injected.");
STATISTIC(NumVFDeclAdded,
"Number of function declarations that have been added.");
STATISTIC(NumCompUsedAdded,
"Number of `@llvm.compiler.used` operands that have been added.");
/// A helper function that adds the vector variant declaration for vectorizing
/// the CallInst \p CI with a vectorization factor of \p VF lanes. For each
/// mapping, TLI provides a VABI prefix, which contains all information required
/// to create vector function declaration.
static void addVariantDeclaration(CallInst &CI, const ElementCount &VF,
const VecDesc *VD) {
Module *M = CI.getModule();
FunctionType *ScalarFTy = CI.getFunctionType();
assert(!ScalarFTy->isVarArg() && "VarArg functions are not supported.");
const std::optional<VFInfo> Info = VFABI::tryDemangleForVFABI(
VD->getVectorFunctionABIVariantString(), ScalarFTy);
assert(Info && "Failed to demangle vector variant");
assert(Info->Shape.VF == VF && "Mangled name does not match VF");
const StringRef VFName = VD->getVectorFnName();
FunctionType *VectorFTy = VFABI::createFunctionType(*Info, ScalarFTy);
Function *VecFunc =
Function::Create(VectorFTy, Function::ExternalLinkage, VFName, M);
VecFunc->copyAttributesFrom(CI.getCalledFunction());
if (auto CC = VD->getCallingConv())
VecFunc->setCallingConv(*CC);
++NumVFDeclAdded;
LLVM_DEBUG(dbgs() << DEBUG_TYPE << ": Added to the module: `" << VFName
<< "` of type " << *VectorFTy << "\n");
// Make function declaration (without a body) "sticky" in the IR by
// listing it in the @llvm.compiler.used intrinsic.
assert(!VecFunc->size() && "VFABI attribute requires `@llvm.compiler.used` "
"only on declarations.");
appendToCompilerUsed(*M, {VecFunc});
LLVM_DEBUG(dbgs() << DEBUG_TYPE << ": Adding `" << VFName
<< "` to `@llvm.compiler.used`.\n");
++NumCompUsedAdded;
}
static void addMappingsFromTLI(const TargetLibraryInfo &TLI, CallInst &CI) {
// This is needed to make sure we don't query the TLI for calls to
// bitcast of function pointers, like `%call = call i32 (i32*, ...)
// bitcast (i32 (...)* @goo to i32 (i32*, ...)*)(i32* nonnull %i)`,
// as such calls make the `isFunctionVectorizable` raise an
// exception.
if (CI.isNoBuiltin() || !CI.getCalledFunction())
return;
StringRef ScalarName = CI.getCalledFunction()->getName();
// Nothing to be done if the TLI thinks the function is not
// vectorizable.
if (!TLI.isFunctionVectorizable(ScalarName))
return;
SmallVector<std::string, 8> Mappings;
VFABI::getVectorVariantNames(CI, Mappings);
Module *M = CI.getModule();
const SetVector<StringRef> OriginalSetOfMappings(llvm::from_range, Mappings);
auto AddVariantDecl = [&](const ElementCount &VF, bool Predicate) {
const VecDesc *VD = TLI.getVectorMappingInfo(ScalarName, VF, Predicate);
if (VD && !VD->getVectorFnName().empty()) {
std::string MangledName = VD->getVectorFunctionABIVariantString();
if (!OriginalSetOfMappings.count(MangledName)) {
Mappings.push_back(MangledName);
++NumCallInjected;
}
Function *VariantF = M->getFunction(VD->getVectorFnName());
if (!VariantF)
addVariantDeclaration(CI, VF, VD);
}
};
// All VFs in the TLI are powers of 2.
ElementCount WidestFixedVF, WidestScalableVF;
TLI.getWidestVF(ScalarName, WidestFixedVF, WidestScalableVF);
for (bool Predicated : {false, true}) {
for (ElementCount VF = ElementCount::getFixed(2);
ElementCount::isKnownLE(VF, WidestFixedVF); VF *= 2)
AddVariantDecl(VF, Predicated);
for (ElementCount VF = ElementCount::getScalable(2);
ElementCount::isKnownLE(VF, WidestScalableVF); VF *= 2)
AddVariantDecl(VF, Predicated);
}
VFABI::setVectorVariantNames(&CI, Mappings);
}
static bool runImpl(const TargetLibraryInfo &TLI, Function &F) {
for (auto &I : instructions(F))
if (auto CI = dyn_cast<CallInst>(&I))
addMappingsFromTLI(TLI, *CI);
// Even if the pass adds IR attributes, the analyses are preserved.
return false;
}
////////////////////////////////////////////////////////////////////////////////
// New pass manager implementation.
////////////////////////////////////////////////////////////////////////////////
PreservedAnalyses InjectTLIMappings::run(Function &F,
FunctionAnalysisManager &AM) {
const TargetLibraryInfo &TLI = AM.getResult<TargetLibraryAnalysis>(F);
runImpl(TLI, F);
// Even if the pass adds IR attributes, the analyses are preserved.
return PreservedAnalyses::all();
}
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