[lld] r276243 - [ELF] - Initial support of tree-style linker script implemented.
George Rimar via llvm-commits
llvm-commits at lists.llvm.org
Wed Jul 20 23:43:02 PDT 2016
Author: grimar
Date: Thu Jul 21 01:43:01 2016
New Revision: 276243
URL: http://llvm.org/viewvc/llvm-project?rev=276243&view=rev
Log:
[ELF] - Initial support of tree-style linker script implemented.
Approach uses LLVM-style RTTI for representing the linker script
commands in a form of tree for future simplification of parsing.
Core idea and code sample belongs to Rui Ueyama.
Differential revision: https://reviews.llvm.org/D22604
Modified:
lld/trunk/ELF/LinkerScript.cpp
lld/trunk/ELF/LinkerScript.h
Modified: lld/trunk/ELF/LinkerScript.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/LinkerScript.cpp?rev=276243&r1=276242&r2=276243&view=diff
==============================================================================
--- lld/trunk/ELF/LinkerScript.cpp (original)
+++ lld/trunk/ELF/LinkerScript.cpp Thu Jul 21 01:43:01 2016
@@ -39,6 +39,14 @@ using namespace lld::elf;
ScriptConfiguration *elf::ScriptConfig;
+bool SymbolAssignment::classof(const BaseCommand *C) {
+ return C->Kind == AssignmentKind;
+}
+
+bool OutputSectionCommand::classof(const BaseCommand *C) {
+ return C->Kind == OutputSectionKind;
+}
+
// This is an operator-precedence parser to parse and evaluate
// a linker script expression. For each linker script arithmetic
// expression (e.g. ". = . + 0x1000"), a new instance of ExprParser
@@ -259,7 +267,7 @@ void LinkerScript<ELFT>::assignAddresses
for (OutputSectionBase<ELFT> *Sec : Sections) {
StringRef Name = Sec->getName();
if (getSectionIndex(Name) == INT_MAX)
- Opt.Commands.push_back({SectionKind, {}, Name, {}});
+ Opt.Commands.push_back(llvm::make_unique<OutputSectionCommand>(Name));
}
// Assign addresses as instructed by linker script SECTIONS sub-commands.
@@ -267,14 +275,14 @@ void LinkerScript<ELFT>::assignAddresses
uintX_t MinVA = std::numeric_limits<uintX_t>::max();
uintX_t ThreadBssOffset = 0;
- for (SectionsCommand &Cmd : Opt.Commands) {
- if (Cmd.Kind == AssignmentKind) {
- uint64_t Val = evalExpr(Cmd.Expr, Dot);
+ for (const std::unique_ptr<BaseCommand> &Base : Opt.Commands) {
+ if (auto *Cmd = dyn_cast<SymbolAssignment>(Base.get())) {
+ uint64_t Val = evalExpr(Cmd->Expr, Dot);
+ if (Cmd->Name == ".") {
- if (Cmd.Name == ".") {
Dot = Val;
} else {
- auto *D = cast<DefinedRegular<ELFT>>(Symtab<ELFT>::X->find(Cmd.Name));
+ auto *D = cast<DefinedRegular<ELFT>>(Symtab<ELFT>::X->find(Cmd->Name));
D->Value = Val;
}
continue;
@@ -283,9 +291,9 @@ void LinkerScript<ELFT>::assignAddresses
// Find all the sections with required name. There can be more than
// one section with such name, if the alignment, flags or type
// attribute differs.
- assert(Cmd.Kind == SectionKind);
+ auto *Cmd = cast<OutputSectionCommand>(Base.get());
for (OutputSectionBase<ELFT> *Sec : Sections) {
- if (Sec->getName() != Cmd.Name)
+ if (Sec->getName() != Cmd->Name)
continue;
if ((Sec->getFlags() & SHF_TLS) && Sec->getType() == SHT_NOBITS) {
@@ -412,13 +420,16 @@ ArrayRef<uint8_t> LinkerScript<ELFT>::ge
// SECTIONS commands. Sections are laid out as the same order as they
// were in the script. If a given name did not appear in the script,
// it returns INT_MAX, so that it will be laid out at end of file.
-template <class ELFT>
-int LinkerScript<ELFT>::getSectionIndex(StringRef Name) {
+template <class ELFT> int LinkerScript<ELFT>::getSectionIndex(StringRef Name) {
auto Begin = Opt.Commands.begin();
auto End = Opt.Commands.end();
- auto I = std::find_if(Begin, End, [&](SectionsCommand &N) {
- return N.Kind == SectionKind && N.Name == Name;
- });
+ auto I =
+ std::find_if(Begin, End, [&](const std::unique_ptr<BaseCommand> &Base) {
+ if (auto *Cmd = dyn_cast<OutputSectionCommand>(Base.get()))
+ if (Cmd->Name == Name)
+ return true;
+ return false;
+ });
return I == End ? INT_MAX : (I - Begin);
}
@@ -433,12 +444,11 @@ int LinkerScript<ELFT>::compareSections(
return I < J ? -1 : 1;
}
-template <class ELFT>
-void LinkerScript<ELFT>::addScriptedSymbols() {
- for (SectionsCommand &Cmd : Opt.Commands)
- if (Cmd.Kind == AssignmentKind)
- if (Cmd.Name != "." && Symtab<ELFT>::X->find(Cmd.Name) == nullptr)
- Symtab<ELFT>::X->addAbsolute(Cmd.Name, STV_DEFAULT);
+template <class ELFT> void LinkerScript<ELFT>::addScriptedSymbols() {
+ for (const std::unique_ptr<BaseCommand> &Base : Opt.Commands)
+ if (auto *Cmd = dyn_cast<SymbolAssignment>(Base.get()))
+ if (Cmd->Name != "." && Symtab<ELFT>::X->find(Cmd->Name) == nullptr)
+ Symtab<ELFT>::X->addAbsolute(Cmd->Name, STV_DEFAULT);
}
template <class ELFT> bool LinkerScript<ELFT>::hasPhdrsCommands() {
@@ -451,15 +461,16 @@ template <class ELFT> bool LinkerScript<
template <class ELFT>
std::vector<size_t>
LinkerScript<ELFT>::getPhdrIndicesForSection(StringRef Name) {
- for (SectionsCommand &Cmd : Opt.Commands) {
- if (Cmd.Kind != SectionKind || Cmd.Name != Name)
+ for (const std::unique_ptr<BaseCommand> &Base : Opt.Commands) {
+ auto *Cmd = dyn_cast<OutputSectionCommand>(Base.get());
+ if (!Cmd || Cmd->Name != Name)
continue;
std::vector<size_t> Indices;
- for (StringRef PhdrName : Cmd.Phdrs) {
+ for (StringRef PhdrName : Cmd->Phdrs) {
auto ItPhdr =
std::find_if(Opt.PhdrsCommands.rbegin(), Opt.PhdrsCommands.rend(),
- [&](PhdrsCommand &Cmd) { return Cmd.Name == PhdrName; });
+ [&](PhdrsCommand &P) { return P.Name == PhdrName; });
if (ItPhdr == Opt.PhdrsCommands.rend())
error("section header '" + PhdrName + "' is not listed in PHDRS");
else
@@ -705,12 +716,12 @@ void ScriptParser::readLocationCounterVa
if (Expr.empty())
error("error in location counter expression");
else
- Opt.Commands.push_back({AssignmentKind, std::move(Expr), ".", {}});
+ Opt.Commands.push_back(llvm::make_unique<SymbolAssignment>(".", Expr));
}
void ScriptParser::readOutputSectionDescription(StringRef OutSec) {
- Opt.Commands.push_back({SectionKind, {}, OutSec, {}});
- SectionsCommand &Cmd = Opt.Commands.back();
+ OutputSectionCommand *Cmd = new OutputSectionCommand(OutSec);
+ Opt.Commands.emplace_back(Cmd);
expect(":");
expect("{");
@@ -734,7 +745,7 @@ void ScriptParser::readOutputSectionDesc
setError("unknown command " + Tok);
}
}
- Cmd.Phdrs = readOutputSectionPhdrs();
+ Cmd->Phdrs = readOutputSectionPhdrs();
StringRef Tok = peek();
if (Tok.startswith("=")) {
@@ -754,7 +765,7 @@ void ScriptParser::readSymbolAssignment(
if (Expr.empty())
error("error in symbol assignment expression");
else
- Opt.Commands.push_back({AssignmentKind, std::move(Expr), Name, {}});
+ Opt.Commands.push_back(llvm::make_unique<SymbolAssignment>(Name, Expr));
}
std::vector<StringRef> ScriptParser::readSectionsCommandExpr() {
Modified: lld/trunk/ELF/LinkerScript.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/LinkerScript.h?rev=276243&r1=276242&r2=276243&view=diff
==============================================================================
--- lld/trunk/ELF/LinkerScript.h (original)
+++ lld/trunk/ELF/LinkerScript.h Thu Jul 21 01:43:01 2016
@@ -41,16 +41,37 @@ struct SectionRule {
StringRef SectionPattern;
};
-// This enum represents what we can observe in SECTIONS tag of script:
-// ExprKind is a location counter change, like ". = . + 0x1000"
-// SectionKind is a description of output section, like ".data :..."
-enum SectionsCommandKind { SectionKind, AssignmentKind };
+// This enum represents what we can observe in SECTIONS tag of script.
+// Each sections-command may of be one of the following:
+// (https://sourceware.org/binutils/docs/ld/SECTIONS.html#SECTIONS)
+// * An ENTRY command.
+// * A symbol assignment.
+// * An output section description.
+// * An overlay description.
+// We support only AssignmentKind and OutputSectionKind for now.
+enum SectionsCommandKind { AssignmentKind, OutputSectionKind };
+
+struct BaseCommand {
+ BaseCommand(int K) : Kind(K) {}
+ virtual ~BaseCommand() {}
+ int Kind;
+};
-struct SectionsCommand {
- SectionsCommandKind Kind;
+struct SymbolAssignment : BaseCommand {
+ SymbolAssignment(StringRef Name, std::vector<StringRef> &Expr)
+ : BaseCommand(AssignmentKind), Name(Name), Expr(std::move(Expr)) {}
+ static bool classof(const BaseCommand *C);
+ StringRef Name;
std::vector<StringRef> Expr;
+};
+
+struct OutputSectionCommand : BaseCommand {
+ OutputSectionCommand(StringRef Name)
+ : BaseCommand(OutputSectionKind), Name(Name) {}
+ static bool classof(const BaseCommand *C);
StringRef Name;
std::vector<StringRef> Phdrs;
+ std::vector<uint8_t> Filler;
};
struct PhdrsCommand {
@@ -69,7 +90,7 @@ struct ScriptConfiguration {
llvm::StringMap<std::vector<uint8_t>> Filler;
// Used to assign addresses to sections.
- std::vector<SectionsCommand> Commands;
+ std::vector<std::unique_ptr<BaseCommand>> Commands;
// Used to assign sections to headers.
std::vector<PhdrsCommand> PhdrsCommands;
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