llvm-mc: Clean up some handling of symbol/section association to be more correct
(external was really undefined and there wasn't an explicit representation for absolute symbols). - This still needs some cleanup to how the absolute "pseudo" section is dealt with, but I haven't figured out the nicest approach yet. llvm-svn: 79733
This commit is contained in:
Daniel Dunbar
parent
81c0524102
commit
6860ac7375
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@ -16,6 +16,7 @@
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#include <string>
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#include "llvm/ADT/StringRef.h"
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#include "llvm/Support/DataTypes.h"
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namespace llvm {
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class MCSection;
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@ -30,39 +31,69 @@ namespace llvm {
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/// it is a reference to an external entity, it has a null section.
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///
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class MCSymbol {
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// Special sentinal value for the absolute pseudo section.
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//
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// FIXME: Use a PointerInt wrapper for this?
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static const MCSection *AbsolutePseudoSection;
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/// Name - The name of the symbol.
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std::string Name;
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/// Section - The section the symbol is defined in, or null if the symbol
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/// has not been defined in the associated translation unit.
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/// Section - The section the symbol is defined in. This is null for
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/// undefined symbols, and the special AbsolutePseudoSection value for
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/// absolute symbols.
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const MCSection *Section;
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/// IsTemporary - True if this is an assembler temporary label, which
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/// typically does not survive in the .o file's symbol table. Usually
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/// "Lfoo" or ".foo".
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unsigned IsTemporary : 1;
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/// IsExternal - True if this symbol has been implicitly defined as an
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/// external, for example by using it in an expression without ever emitting
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/// it as a label. The @var Section for an external symbol is always null.
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unsigned IsExternal : 1;
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private: // MCContext creates and uniques these.
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friend class MCContext;
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MCSymbol(const StringRef &_Name, bool _IsTemporary)
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: Name(_Name), Section(0), IsTemporary(_IsTemporary), IsExternal(false) {}
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: Name(_Name), Section(0),
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IsTemporary(_IsTemporary) {}
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MCSymbol(const MCSymbol&); // DO NOT IMPLEMENT
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void operator=(const MCSymbol&); // DO NOT IMPLEMENT
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public:
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const MCSection *getSection() const { return Section; }
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void setSection(const MCSection *S) { Section = S; }
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bool isExternal() const { return IsExternal; }
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void setExternal(bool Value) { IsExternal = Value; }
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/// getName - Get the symbol name.
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const std::string &getName() const { return Name; }
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/// @name Symbol Location Functions
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/// @{
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/// isUndefined - Check if this symbol undefined (i.e., implicitly defined).
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bool isUndefined() const {
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return Section == 0;
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}
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/// isAbsolute - Check if this this is an absolute symbol.
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bool isAbsolute() const {
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return Section == AbsolutePseudoSection;
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}
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/// getSection - Get the section associated with a defined, non-absolute
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/// symbol.
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const MCSection &getSection() const {
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assert(!isUndefined() && !isAbsolute() && "Invalid accessor!");
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return *Section;
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}
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/// setSection - Mark the symbol as defined in the section \arg S.
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void setSection(const MCSection &S) { Section = &S; }
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/// setUndefined - Mark the symbol as undefined.
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void setUndefined() {
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Section = 0;
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}
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/// setAbsolute - Mark the symbol as absolute.
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void setAbsolute() { Section = AbsolutePseudoSection; }
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/// @}
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/// print - Print the value to the stream \arg OS.
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void print(raw_ostream &OS) const;
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@ -49,9 +49,10 @@ public:
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///
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/// @result - The value's associated section, or null for external or constant
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/// values.
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const MCSection *getAssociatedSection() const {
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return SymA ? SymA->getSection() : 0;
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}
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//
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// FIXME: Switch to a tagged section, so this can return the tagged section
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// value.
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const MCSection *getAssociatedSection() const;
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/// print - Print the value to the stream \arg OS.
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void print(raw_ostream &OS) const;
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@ -107,14 +107,11 @@ void MCAsmStreamer::SwitchSection(const MCSection *Section) {
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}
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void MCAsmStreamer::EmitLabel(MCSymbol *Symbol) {
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assert(Symbol->getSection() == 0 && "Cannot emit a symbol twice!");
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assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
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assert(CurSection && "Cannot emit before setting section!");
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assert(!getContext().GetSymbolValue(Symbol) &&
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"Cannot emit symbol which was directly assigned to!");
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OS << Symbol << ":\n";
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Symbol->setSection(CurSection);
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Symbol->setExternal(false);
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Symbol->setSection(*CurSection);
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}
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void MCAsmStreamer::EmitAssemblerFlag(AssemblerFlag Flag) {
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@ -127,7 +124,9 @@ void MCAsmStreamer::EmitAssemblerFlag(AssemblerFlag Flag) {
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void MCAsmStreamer::EmitAssignment(MCSymbol *Symbol, const MCValue &Value,
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bool MakeAbsolute) {
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assert(!Symbol->getSection() && "Cannot assign to a label!");
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// Only absolute symbols can be redefined.
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assert((Symbol->isUndefined() || Symbol->isAbsolute()) &&
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"Cannot define a symbol twice!");
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if (MakeAbsolute) {
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OS << ".set " << Symbol << ", " << Value << '\n';
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@ -91,15 +91,12 @@ void MCMachOStreamer::SwitchSection(const MCSection *Section) {
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}
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void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
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assert(Symbol->getSection() == 0 && "Cannot emit a symbol twice!");
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assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
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assert(CurSection && "Cannot emit before setting section!");
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assert(!getContext().GetSymbolValue(Symbol) &&
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"Cannot emit symbol which was directly assigned to!");
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llvm_unreachable("FIXME: Not yet implemented!");
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Symbol->setSection(CurSection);
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Symbol->setExternal(false);
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Symbol->setSection(*CurSection);
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}
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void MCMachOStreamer::EmitAssemblerFlag(AssemblerFlag Flag) {
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@ -109,7 +106,9 @@ void MCMachOStreamer::EmitAssemblerFlag(AssemblerFlag Flag) {
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void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol,
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const MCValue &Value,
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bool MakeAbsolute) {
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assert(!Symbol->getSection() && "Cannot assign to a label!");
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// Only absolute symbols can be redefined.
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assert((Symbol->isUndefined() || Symbol->isAbsolute()) &&
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"Cannot define a symbol twice!");
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llvm_unreachable("FIXME: Not yet implemented!");
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}
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@ -12,6 +12,10 @@
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using namespace llvm;
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// Sentinel value for the absolute pseudo section.
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const MCSection *MCSymbol::AbsolutePseudoSection =
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reinterpret_cast<const MCSection *>(1);
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/// NeedsQuoting - Return true if the string \arg Str needs quoting, i.e., it
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/// does not match [a-zA-Z_.][a-zA-Z0-9_.]*.
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//
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@ -2,32 +2,56 @@
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import struct
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import sys
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import StringIO
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class Reader:
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def __init__(self, path):
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if path == '-':
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self.file = sys.stdin
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# Snarf all the data so we can seek.
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self.file = StringIO.StringIO(sys.stdin.read())
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else:
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self.file = open(path,'rb')
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self.isLSB = None
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self.pos = 0
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self.string_table = None
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def setLSB(self, isLSB):
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self.isLSB = bool(isLSB)
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def tell(self):
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return self.pos
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return self.file.tell()
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def seek(self, pos):
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self.file.seek(pos)
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def read(self, N):
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data = self.file.read(N)
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self.pos += len(data)
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if len(data) != N:
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raise ValueError,"Out of data!"
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return data
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def read8(self):
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return ord(self.read(1))
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def read16(self):
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return struct.unpack('><'[self.isLSB] + 'H', self.read(2))[0]
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def read32(self):
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return struct.unpack('><'[self.isLSB] + 'I', self.read(4))[0]
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def registerStringTable(self, strings):
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if self.string_table is not None:
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raise ValueError,"%s: warning: multiple string tables" % sys.argv[0]
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self.string_table = strings
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def getString(self, index):
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if self.string_table is None:
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raise ValueError,"%s: warning: no string table registered" % sys.argv[0]
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end = self.string_table.index('\x00', index)
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return self.string_table[index:end]
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def dumpmacho(path, opts):
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f = Reader(path)
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@ -60,7 +84,7 @@ def dumpmacho(path, opts):
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print "])"
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if f.tell() - start != loadCommandsSize:
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raise ValueError,"%s: warning: invalid load commands size: %r" % (sys.argv, loadCommandsSize)
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raise ValueError,"%s: warning: invalid load commands size: %r" % (sys.argv[0], loadCommandsSize)
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def dumpLoadCommand(f, i, opts):
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start = f.tell()
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@ -83,7 +107,7 @@ def dumpLoadCommand(f, i, opts):
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print " ),"
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if f.tell() - start != cmdSize:
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raise ValueError,"%s: warning: invalid load command size: %r" % (sys.argv, cmdSize)
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raise ValueError,"%s: warning: invalid load command size: %r" % (sys.argv[0], cmdSize)
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def dumpSegmentLoadCommand32(f, opts):
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print " ('segment_name', %r)" % f.read(16)
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@ -103,10 +127,45 @@ def dumpSegmentLoadCommand32(f, opts):
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print " ])"
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def dumpSymtabCommand(f, opts):
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print " ('symoff', %r)" % f.read32()
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print " ('nsyms', %r)" % f.read32()
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print " ('stroff', %r)" % f.read32()
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print " ('strsize', %r)" % f.read32()
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symoff = f.read32()
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print " ('symoff', %r)" % symoff
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nsyms = f.read32()
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print " ('nsyms', %r)" % nsyms
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stroff = f.read32()
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print " ('stroff', %r)" % stroff
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strsize = f.read32()
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print " ('strsize', %r)" % strsize
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prev_pos = f.tell()
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f.seek(stroff)
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string_data = f.read(strsize)
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print " ('_string_data', %r)" % string_data
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f.registerStringTable(string_data)
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f.seek(symoff)
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print " ('_symbols', ["
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for i in range(nsyms):
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dumpNlist32(f, i, opts)
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print " ])"
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f.seek(prev_pos)
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def dumpNlist32(f, i, opts):
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print " # Symbol %r" % i
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n_strx = f.read32()
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print " (('n_strx', %r)" % n_strx
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n_type = f.read8()
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print " ('n_type', %#x)" % n_type
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n_sect = f.read8()
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print " ('n_type', %r)" % n_sect
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n_desc = f.read16()
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print " ('n_desc', %r)" % n_desc
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n_value = f.read32()
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print " ('n_value', %r)" % n_value
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print " ('_string', %r)" % f.getString(n_strx)
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print " ),"
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def dumpDysymtabCommand(f, opts):
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print " ('ilocalsym', %r)" % f.read32()
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@ -121,13 +180,26 @@ def dumpDysymtabCommand(f, opts):
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print " ('nmodtab', %r)" % f.read32()
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print " ('extrefsymoff', %r)" % f.read32()
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print " ('nextrefsyms', %r)" % f.read32()
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print " ('indirectsymoff', %r)" % f.read32()
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print " ('nindirectsyms', %r)" % f.read32()
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indirectsymoff = f.read32()
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print " ('indirectsymoff', %r)" % indirectsymoff
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nindirectsyms = f.read32()
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print " ('nindirectsyms', %r)" % nindirectsyms
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print " ('extreloff', %r)" % f.read32()
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print " ('nextrel', %r)" % f.read32()
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print " ('locreloff', %r)" % f.read32()
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print " ('nlocrel', %r)" % f.read32()
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prev_pos = f.tell()
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f.seek(indirectsymoff)
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print " ('_indirect_symbols', ["
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for i in range(nindirectsyms):
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print " # Indirect Symbol %r" % i
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print " (('symbol_index', %r),)," % f.read32()
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print " ])"
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f.seek(prev_pos)
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def dumpSection32(f, i, opts):
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print " # Section %r" % i
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print " (('section_name', %r)" % f.read(16)
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@ -149,10 +149,6 @@ bool AsmParser::ParsePrimaryExpr(AsmExpr *&Res) {
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// This is a label, this should be parsed as part of an expression, to
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// handle things like LFOO+4.
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MCSymbol *Sym = Ctx.GetOrCreateSymbol(Lexer.getTok().getIdentifier());
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// If this is use of an undefined symbol then mark it external.
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if (!Sym->getSection() && !Ctx.GetSymbolValue(Sym))
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Sym->setExternal(true);
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Res = new AsmSymbolRefExpr(Sym);
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Lexer.Lex(); // Eat identifier.
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@ -376,10 +372,8 @@ bool AsmParser::ParseStatement() {
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// FIXME: This doesn't diagnose assignment to a symbol which has been
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// implicitly marked as external.
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MCSymbol *Sym = Ctx.GetOrCreateSymbol(IDVal);
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if (Sym->getSection())
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if (!Sym->isUndefined())
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return Error(IDLoc, "invalid symbol redefinition");
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if (Ctx.GetSymbolValue(Sym))
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return Error(IDLoc, "symbol already used as assembler variable");
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// Since we saw a label, create a symbol and emit it.
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// FIXME: If the label starts with L it is an assembler temporary label.
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@ -687,15 +681,11 @@ bool AsmParser::ParseAssignment(const StringRef &Name, bool IsDotSet) {
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// Diagnose assignment to a label.
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//
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// FIXME: Diagnostics. Note the location of the definition as a label.
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// FIXME: This doesn't diagnose assignment to a symbol which has been
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// implicitly marked as external.
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// FIXME: Handle '.'.
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// FIXME: Diagnose assignment to protected identifier (e.g., register name).
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MCSymbol *Sym = Ctx.GetOrCreateSymbol(Name);
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if (Sym->getSection())
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return Error(EqualLoc, "invalid assignment to symbol emitted as a label");
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if (Sym->isExternal())
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return Error(EqualLoc, "invalid assignment to external symbol");
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if (!Sym->isUndefined() && !Sym->isAbsolute())
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return Error(EqualLoc, "symbol has already been defined");
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// Do the assignment.
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Out.EmitAssignment(Sym, Value, IsDotSet);
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@ -1117,10 +1107,6 @@ bool AsmParser::ParseDirectiveSymbolAttribute(MCStreamer::SymbolAttr Attr) {
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MCSymbol *Sym = Ctx.GetOrCreateSymbol(Name);
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// If this is use of an undefined symbol then mark it external.
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if (!Sym->getSection() && !Ctx.GetSymbolValue(Sym))
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Sym->setExternal(true);
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Out.EmitSymbolAttribute(Sym, Attr);
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if (Lexer.is(AsmToken::EndOfStatement))
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@ -1213,8 +1199,7 @@ bool AsmParser::ParseDirectiveComm(bool IsLocal) {
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return Error(Pow2AlignmentLoc, "invalid '.comm' or '.lcomm' directive "
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"alignment, can't be less than zero");
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// TODO: Symbol must be undefined or it is a error to re-defined the symbol
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if (Sym->getSection() || Ctx.GetSymbolValue(Sym))
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if (!Sym->isUndefined())
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return Error(IDLoc, "invalid symbol redefinition");
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// Create the Symbol as a common or local common with Size and Pow2Alignment
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@ -1305,8 +1290,7 @@ bool AsmParser::ParseDirectiveDarwinZerofill() {
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return Error(Pow2AlignmentLoc, "invalid '.zerofill' directive alignment, "
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"can't be less than zero");
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// TODO: Symbol must be undefined or it is a error to re-defined the symbol
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if (Sym->getSection() || Ctx.GetSymbolValue(Sym))
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if (!Sym->isUndefined())
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return Error(IDLoc, "invalid symbol redefinition");
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// FIXME: Arch specific.
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