vendor/llvm/llvm-trunk-r366426

1 files changed, 99 insertions, 4 deletions

diff --git a/lib/Target/RISCV/RISCVTargetObjectFile.cpp b/lib/Target/RISCV/RISCVTargetObjectFile.cpp
index 46e81b628b65..bbd45c970d3d 100644
--- a/lib/Target/RISCV/RISCVTargetObjectFile.cpp
+++ b/lib/Target/RISCV/RISCVTargetObjectFile.cpp
@@ -1,14 +1,16 @@
 //===-- RISCVTargetObjectFile.cpp - RISCV Object Info -----------------===//
 //
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// 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
 //
 //===----------------------------------------------------------------------===//
 
 #include "RISCVTargetObjectFile.h"
 #include "RISCVTargetMachine.h"
+#include "llvm/BinaryFormat/ELF.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCSectionELF.h"
 
 using namespace llvm;
 
@@ -16,4 +18,97 @@ void RISCVELFTargetObjectFile::Initialize(MCContext &Ctx,
                                           const TargetMachine &TM) {
   TargetLoweringObjectFileELF::Initialize(Ctx, TM);
   InitializeELF(TM.Options.UseInitArray);
+
+  SmallDataSection = getContext().getELFSection(
+      ".sdata", ELF::SHT_PROGBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
+  SmallBSSSection = getContext().getELFSection(".sbss", ELF::SHT_NOBITS,
+                                               ELF::SHF_WRITE | ELF::SHF_ALLOC);
+}
+
+// A address must be loaded from a small section if its size is less than the
+// small section size threshold. Data in this section could be addressed by
+// using gp_rel operator.
+bool RISCVELFTargetObjectFile::isInSmallSection(uint64_t Size) const {
+  // gcc has traditionally not treated zero-sized objects as small data, so this
+  // is effectively part of the ABI.
+  return Size > 0 && Size <= SSThreshold;
+}
+
+// Return true if this global address should be placed into small data/bss
+// section.
+bool RISCVELFTargetObjectFile::isGlobalInSmallSection(
+    const GlobalObject *GO, const TargetMachine &TM) const {
+  // Only global variables, not functions.
+  const GlobalVariable *GVA = dyn_cast<GlobalVariable>(GO);
+  if (!GVA)
+    return false;
+
+  // If the variable has an explicit section, it is placed in that section.
+  if (GVA->hasSection()) {
+    StringRef Section = GVA->getSection();
+
+    // Explicitly placing any variable in the small data section overrides
+    // the global -G value.
+    if (Section == ".sdata" || Section == ".sbss")
+      return true;
+
+    // Otherwise reject putting the variable to small section if it has an
+    // explicit section name.
+    return false;
+  }
+
+  if (((GVA->hasExternalLinkage() && GVA->isDeclaration()) ||
+       GVA->hasCommonLinkage()))
+    return false;
+
+  Type *Ty = GVA->getValueType();
+  // It is possible that the type of the global is unsized, i.e. a declaration
+  // of a extern struct. In this case don't presume it is in the small data
+  // section. This happens e.g. when building the FreeBSD kernel.
+  if (!Ty->isSized())
+    return false;
+
+  return isInSmallSection(
+      GVA->getParent()->getDataLayout().getTypeAllocSize(Ty));
+}
+
+MCSection *RISCVELFTargetObjectFile::SelectSectionForGlobal(
+    const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
+  // Handle Small Section classification here.
+  if (Kind.isBSS() && isGlobalInSmallSection(GO, TM))
+    return SmallBSSSection;
+  if (Kind.isData() && isGlobalInSmallSection(GO, TM))
+    return SmallDataSection;
+
+  // Otherwise, we work the same as ELF.
+  return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, Kind, TM);
+}
+
+void RISCVELFTargetObjectFile::getModuleMetadata(Module &M) {
+  SmallVector<Module::ModuleFlagEntry, 8> ModuleFlags;
+  M.getModuleFlagsMetadata(ModuleFlags);
+
+  for (const auto &MFE : ModuleFlags) {
+    StringRef Key = MFE.Key->getString();
+    if (Key == "SmallDataLimit") {
+      SSThreshold = mdconst::extract<ConstantInt>(MFE.Val)->getZExtValue();
+      break;
+    }
+  }
+}
+
+/// Return true if this constant should be placed into small data section.
+bool RISCVELFTargetObjectFile::isConstantInSmallSection(
+    const DataLayout &DL, const Constant *CN) const {
+  return isInSmallSection(DL.getTypeAllocSize(CN->getType()));
+}
+
+MCSection *RISCVELFTargetObjectFile::getSectionForConstant(
+    const DataLayout &DL, SectionKind Kind, const Constant *C,
+    unsigned &Align) const {
+  if (isConstantInSmallSection(DL, C))
+    return SmallDataSection;
+
+  // Otherwise, we work the same as ELF.
+  return TargetLoweringObjectFileELF::getSectionForConstant(DL, Kind, C, Align);
 }