forked from OSchip/llvm-project
392 lines
14 KiB
C++
392 lines
14 KiB
C++
//===-- HexagonTargetObjectFile.cpp ---------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains the declarations of the HexagonTargetAsmInfo properties.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "hexagon-sdata"
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#include "HexagonTargetMachine.h"
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#include "HexagonTargetObjectFile.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/GlobalVariable.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/ELF.h"
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using namespace llvm;
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static cl::opt<unsigned> SmallDataThreshold("hexagon-small-data-threshold",
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cl::init(8), cl::Hidden,
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cl::desc("The maximum size of an object in the sdata section"));
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static cl::opt<bool> NoSmallDataSorting("mno-sort-sda", cl::init(false),
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cl::Hidden, cl::desc("Disable small data sections sorting"));
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static cl::opt<bool> StaticsInSData("hexagon-statics-in-small-data",
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cl::init(false), cl::Hidden, cl::ZeroOrMore,
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cl::desc("Allow static variables in .sdata"));
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static cl::opt<bool> TraceGVPlacement("trace-gv-placement",
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cl::Hidden, cl::init(false),
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cl::desc("Trace global value placement"));
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// TraceGVPlacement controls messages for all builds. For builds with assertions
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// (debug or release), messages are also controlled by the usual debug flags
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// (e.g. -debug and -debug-only=globallayout)
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#define TRACE_TO(s, X) s << X
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#ifdef NDEBUG
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#define TRACE(X) do { if (TraceGVPlacement) { TRACE_TO(errs(), X); } } while (0)
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#else
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#define TRACE(X) \
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do { \
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if (TraceGVPlacement) { TRACE_TO(errs(), X); } \
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else { DEBUG( TRACE_TO(dbgs(), X) ); } \
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} while (0)
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#endif
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// Returns true if the section name is such that the symbol will be put
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// in a small data section.
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// For instance, global variables with section attributes such as ".sdata"
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// ".sdata.*", ".sbss", and ".sbss.*" will go into small data.
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static bool isSmallDataSection(StringRef Sec) {
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// sectionName is either ".sdata" or ".sbss". Looking for an exact match
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// obviates the need for checks for section names such as ".sdatafoo".
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if (Sec.equals(".sdata") || Sec.equals(".sbss") || Sec.equals(".scommon"))
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return true;
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// If either ".sdata." or ".sbss." is a substring of the section name
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// then put the symbol in small data.
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return Sec.find(".sdata.") != StringRef::npos ||
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Sec.find(".sbss.") != StringRef::npos ||
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Sec.find(".scommon.") != StringRef::npos;
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}
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static const char *getSectionSuffixForSize(unsigned Size) {
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switch (Size) {
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default:
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return "";
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case 1:
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return ".1";
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case 2:
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return ".2";
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case 4:
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return ".4";
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case 8:
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return ".8";
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}
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}
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void HexagonTargetObjectFile::Initialize(MCContext &Ctx,
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const TargetMachine &TM) {
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TargetLoweringObjectFileELF::Initialize(Ctx, TM);
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InitializeELF(TM.Options.UseInitArray);
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SmallDataSection =
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getContext().getELFSection(".sdata", ELF::SHT_PROGBITS,
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ELF::SHF_WRITE | ELF::SHF_ALLOC |
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ELF::SHF_HEX_GPREL);
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SmallBSSSection =
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getContext().getELFSection(".sbss", ELF::SHT_NOBITS,
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ELF::SHF_WRITE | ELF::SHF_ALLOC |
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ELF::SHF_HEX_GPREL);
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}
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MCSection *HexagonTargetObjectFile::SelectSectionForGlobal(
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const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
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const TargetMachine &TM) const {
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TRACE("[SelectSectionForGlobal] GV(" << GV->getName() << ") ");
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TRACE("input section(" << GV->getSection() << ") ");
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TRACE((GV->hasPrivateLinkage() ? "private_linkage " : "")
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<< (GV->hasLocalLinkage() ? "local_linkage " : "")
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<< (GV->hasInternalLinkage() ? "internal " : "")
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<< (GV->hasExternalLinkage() ? "external " : "")
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<< (GV->hasCommonLinkage() ? "common_linkage " : "")
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<< (GV->hasCommonLinkage() ? "common " : "" )
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<< (Kind.isCommon() ? "kind_common " : "" )
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<< (Kind.isBSS() ? "kind_bss " : "" )
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<< (Kind.isBSSLocal() ? "kind_bss_local " : "" ));
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if (isGlobalInSmallSection(GV, TM))
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return selectSmallSectionForGlobal(GV, Kind, Mang, TM);
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if (Kind.isCommon()) {
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// This is purely for LTO+Linker Script because commons don't really have a
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// section. However, the BitcodeSectionWriter pass will query for the
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// sections of commons (and the linker expects us to know their section) so
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// we'll return one here.
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return BSSSection;
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}
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TRACE("default_ELF_section\n");
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// Otherwise, we work the same as ELF.
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return TargetLoweringObjectFileELF::SelectSectionForGlobal(GV, Kind,
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Mang, TM);
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}
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MCSection *HexagonTargetObjectFile::getExplicitSectionGlobal(
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const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
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const TargetMachine &TM) const {
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TRACE("[getExplicitSectionGlobal] GV(" << GV->getName() << ") from("
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<< GV->getSection() << ") ");
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TRACE((GV->hasPrivateLinkage() ? "private_linkage " : "")
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<< (GV->hasLocalLinkage() ? "local_linkage " : "")
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<< (GV->hasInternalLinkage() ? "internal " : "")
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<< (GV->hasExternalLinkage() ? "external " : "")
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<< (GV->hasCommonLinkage() ? "common_linkage " : "")
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<< (GV->hasCommonLinkage() ? "common " : "" )
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<< (Kind.isCommon() ? "kind_common " : "" )
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<< (Kind.isBSS() ? "kind_bss " : "" )
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<< (Kind.isBSSLocal() ? "kind_bss_local " : "" ));
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if (GV->hasSection()) {
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StringRef Section = GV->getSection();
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if (Section.find(".access.text.group") != StringRef::npos)
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return getContext().getELFSection(GV->getSection(), ELF::SHT_PROGBITS,
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ELF::SHF_ALLOC | ELF::SHF_EXECINSTR);
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if (Section.find(".access.data.group") != StringRef::npos)
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return getContext().getELFSection(GV->getSection(), ELF::SHT_PROGBITS,
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ELF::SHF_WRITE | ELF::SHF_ALLOC);
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}
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if (isGlobalInSmallSection(GV, TM))
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return selectSmallSectionForGlobal(GV, Kind, Mang, TM);
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// Otherwise, we work the same as ELF.
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TRACE("default_ELF_section\n");
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return TargetLoweringObjectFileELF::getExplicitSectionGlobal(GV, Kind,
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Mang, TM);
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}
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/// Return true if this global value should be placed into small data/bss
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/// section.
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bool HexagonTargetObjectFile::isGlobalInSmallSection(const GlobalValue *GV,
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const TargetMachine &TM) const {
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// Only global variables, not functions.
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DEBUG(dbgs() << "Checking if value is in small-data, -G"
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<< SmallDataThreshold << ": \"" << GV->getName() << "\": ");
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const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
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if (!GVar) {
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DEBUG(dbgs() << "no, not a global variable\n");
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return false;
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}
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// Globals with external linkage that have an original section set must be
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// emitted to that section, regardless of whether we would put them into
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// small data or not. This is how we can support mixing -G0/-G8 in LTO.
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if (GVar->hasSection()) {
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bool IsSmall = isSmallDataSection(GVar->getSection());
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DEBUG(dbgs() << (IsSmall ? "yes" : "no") << ", has section: "
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<< GVar->getSection() << '\n');
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return IsSmall;
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}
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if (GVar->isConstant()) {
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DEBUG(dbgs() << "no, is a constant\n");
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return false;
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}
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bool IsLocal = GVar->hasLocalLinkage();
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if (!StaticsInSData && IsLocal) {
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DEBUG(dbgs() << "no, is static\n");
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return false;
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}
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Type *GType = GVar->getType();
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if (PointerType *PT = dyn_cast<PointerType>(GType))
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GType = PT->getElementType();
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if (isa<ArrayType>(GType)) {
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DEBUG(dbgs() << "no, is an array\n");
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return false;
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}
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// If the type is a struct with no body provided, treat is conservatively.
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// There cannot be actual definitions of object of such a type in this CU
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// (only references), so assuming that they are not in sdata is safe. If
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// these objects end up in the sdata, the references will still be valid.
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if (StructType *ST = dyn_cast<StructType>(GType)) {
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if (ST->isOpaque()) {
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DEBUG(dbgs() << "no, has opaque type\n");
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return false;
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}
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}
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unsigned Size = GVar->getParent()->getDataLayout().getTypeAllocSize(GType);
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if (Size == 0) {
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DEBUG(dbgs() << "no, has size 0\n");
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return false;
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}
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if (Size > SmallDataThreshold) {
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DEBUG(dbgs() << "no, size exceeds sdata threshold: " << Size << '\n');
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return false;
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}
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DEBUG(dbgs() << "yes\n");
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return true;
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}
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bool HexagonTargetObjectFile::isSmallDataEnabled() const {
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return SmallDataThreshold > 0;
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}
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unsigned HexagonTargetObjectFile::getSmallDataSize() const {
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return SmallDataThreshold;
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}
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/// Descends any type down to "elementary" components,
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/// discovering the smallest addressable one.
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/// If zero is returned, declaration will not be modified.
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unsigned HexagonTargetObjectFile::getSmallestAddressableSize(const Type *Ty,
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const GlobalValue *GV, const TargetMachine &TM) const {
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// Assign the smallest element access size to the highest
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// value which assembler can handle.
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unsigned SmallestElement = 8;
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if (!Ty)
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return 0;
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switch (Ty->getTypeID()) {
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case Type::StructTyID: {
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const StructType *STy = cast<const StructType>(Ty);
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for (auto &E : STy->elements()) {
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unsigned AtomicSize = getSmallestAddressableSize(E, GV, TM);
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if (AtomicSize < SmallestElement)
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SmallestElement = AtomicSize;
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}
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return (STy->getNumElements() == 0) ? 0 : SmallestElement;
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}
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case Type::ArrayTyID: {
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const ArrayType *ATy = cast<const ArrayType>(Ty);
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return getSmallestAddressableSize(ATy->getElementType(), GV, TM);
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}
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case Type::VectorTyID: {
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const VectorType *PTy = cast<const VectorType>(Ty);
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return getSmallestAddressableSize(PTy->getElementType(), GV, TM);
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}
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case Type::PointerTyID:
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case Type::HalfTyID:
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case Type::FloatTyID:
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case Type::DoubleTyID:
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case Type::IntegerTyID: {
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const DataLayout &DL = GV->getParent()->getDataLayout();
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// It is unfortunate that DL's function take non-const Type*.
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return DL.getTypeAllocSize(const_cast<Type*>(Ty));
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}
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case Type::FunctionTyID:
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case Type::VoidTyID:
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case Type::X86_FP80TyID:
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case Type::FP128TyID:
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case Type::PPC_FP128TyID:
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case Type::LabelTyID:
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case Type::MetadataTyID:
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case Type::X86_MMXTyID:
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case Type::TokenTyID:
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return 0;
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}
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return 0;
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}
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MCSection *HexagonTargetObjectFile::selectSmallSectionForGlobal(
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const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
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const TargetMachine &TM) const {
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const Type *GTy = GV->getType()->getElementType();
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unsigned Size = getSmallestAddressableSize(GTy, GV, TM);
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// If we have -ffunction-section or -fdata-section then we should emit the
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// global value to a unique section specifically for it... even for sdata.
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bool EmitUniquedSection = TM.getDataSections();
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TRACE("Small data. Size(" << Size << ")");
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// Handle Small Section classification here.
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if (Kind.isBSS() || Kind.isBSSLocal()) {
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// If -mno-sort-sda is not set, find out smallest accessible entity in
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// declaration and add it to the section name string.
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// Note. It does not track the actual usage of the value, only its de-
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// claration. Also, compiler adds explicit pad fields to some struct
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// declarations - they are currently counted towards smallest addres-
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// sable entity.
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if (NoSmallDataSorting) {
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TRACE(" default sbss\n");
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return SmallBSSSection;
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}
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StringRef Prefix(".sbss");
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SmallString<128> Name(Prefix);
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Name.append(getSectionSuffixForSize(Size));
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if (EmitUniquedSection) {
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Name.append(".");
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Name.append(GV->getName());
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}
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TRACE(" unique sbss(" << Name << ")\n");
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return getContext().getELFSection(Name.str(), ELF::SHT_NOBITS,
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ELF::SHF_WRITE | ELF::SHF_ALLOC | ELF::SHF_HEX_GPREL);
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}
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if (Kind.isCommon()) {
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// This is purely for LTO+Linker Script because commons don't really have a
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// section. However, the BitcodeSectionWriter pass will query for the
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// sections of commons (and the linker expects us to know their section) so
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// we'll return one here.
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if (NoSmallDataSorting)
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return BSSSection;
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Twine Name = Twine(".scommon") + getSectionSuffixForSize(Size);
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TRACE(" small COMMON (" << Name << ")\n");
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return getContext().getELFSection(Name.str(), ELF::SHT_NOBITS,
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ELF::SHF_WRITE | ELF::SHF_ALLOC |
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ELF::SHF_HEX_GPREL);
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}
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// We could have changed sdata object to a constant... in this
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// case the Kind could be wrong for it.
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if (Kind.isMergeableConst()) {
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TRACE(" const_object_as_data ");
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const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
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if (GVar->hasSection() && isSmallDataSection(GVar->getSection()))
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Kind = SectionKind::getData();
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}
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if (Kind.isData()) {
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if (NoSmallDataSorting) {
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TRACE(" default sdata\n");
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return SmallDataSection;
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}
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StringRef Prefix(".sdata");
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SmallString<128> Name(Prefix);
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Name.append(getSectionSuffixForSize(Size));
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if (EmitUniquedSection) {
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Name.append(".");
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Name.append(GV->getName());
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}
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TRACE(" unique sdata(" << Name << ")\n");
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return getContext().getELFSection(Name.str(), ELF::SHT_PROGBITS,
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ELF::SHF_WRITE | ELF::SHF_ALLOC | ELF::SHF_HEX_GPREL);
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}
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TRACE("default ELF section\n");
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// Otherwise, we work the same as ELF.
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return TargetLoweringObjectFileELF::SelectSectionForGlobal(GV, Kind,
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Mang, TM);
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}
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