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MC: Cleanup MCSectionMachO::ParseSectionSpecifier
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Split by comma once instead of multiple times.  Moving this upfront
makes the rest of the code considerably simpler.

No functional change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203429 91177308-0d34-0410-b5e6-96231b3b80d8
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@majnemer
majnemer committed Mar 10, 2014
1 parent 9e215b0 commit 5d0bfc8
Showing 1 changed file with 43 additions and 77 deletions.
120 changes: 43 additions & 77 deletions lib/MC/MCSectionMachO.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -48,8 +48,7 @@ static const struct {

/// SectionAttrDescriptors - This is an array of descriptors for section
/// attributes. Unlike the SectionTypeDescriptors, this is not directly indexed
/// by attribute, instead it is searched. The last entry has an AttrFlagEnd
/// AttrFlag value.
/// by attribute, instead it is searched.
static const struct {
unsigned AttrFlag;
const char *AssemblerName, *EnumName;
Expand All @@ -68,8 +67,6 @@ ENTRY(0 /*FIXME*/, S_ATTR_EXT_RELOC)
ENTRY(0 /*FIXME*/, S_ATTR_LOC_RELOC)
#undef ENTRY
{ 0, "none", 0 }, // used if section has no attributes but has a stub size
#define AttrFlagEnd 0xffffffff // non-legal value, multiple attribute bits set
{ AttrFlagEnd, 0, 0 }
};

MCSectionMachO::MCSectionMachO(StringRef Segment, StringRef Section,
Expand Down Expand Up @@ -164,14 +161,6 @@ bool MCSectionMachO::isVirtualSection() const {
getType() == MachO::S_THREAD_LOCAL_ZEROFILL);
}

/// StripSpaces - This removes leading and trailing spaces from the StringRef.
static void StripSpaces(StringRef &Str) {
while (!Str.empty() && isspace(static_cast<unsigned char>(Str[0])))
Str = Str.substr(1);
while (!Str.empty() && isspace(static_cast<unsigned char>(Str.back())))
Str = Str.substr(0, Str.size()-1);
}

/// ParseSectionSpecifier - Parse the section specifier indicated by "Spec".
/// This is a string that can appear after a .section directive in a mach-o
/// flavored .s file. If successful, this fills in the specified Out
Expand All @@ -184,102 +173,83 @@ std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec, // In.
bool &TAAParsed, // Out.
unsigned &StubSize) { // Out.
TAAParsed = false;
// Find the first comma.
std::pair<StringRef, StringRef> Comma = Spec.split(',');

// If there is no comma, we fail.
if (Comma.second.empty())
return "mach-o section specifier requires a segment and section "
"separated by a comma";

// Capture segment, remove leading and trailing whitespace.
Segment = Comma.first;
StripSpaces(Segment);
SmallVector<StringRef, 5> SplitSpec;
Spec.split(SplitSpec, ",");
// Remove leading and trailing whitespace.
auto GetEmptyOrTrim = [&SplitSpec](size_t Idx) -> StringRef {
return SplitSpec.size() > Idx ? SplitSpec[Idx].trim() : StringRef();
};
Segment = GetEmptyOrTrim(0);
Section = GetEmptyOrTrim(1);
StringRef SectionType = GetEmptyOrTrim(2);
StringRef Attrs = GetEmptyOrTrim(3);
StringRef StubSizeStr = GetEmptyOrTrim(4);

// Verify that the segment is present and not too long.
if (Segment.empty() || Segment.size() > 16)
return "mach-o section specifier requires a segment whose length is "
"between 1 and 16 characters";

// Split the section name off from any attributes if present.
Comma = Comma.second.split(',');

// Capture section, remove leading and trailing whitespace.
Section = Comma.first;
StripSpaces(Section);

// Verify that the section is present and not too long.
if (Section.empty() || Section.size() > 16)
if (Section.empty())
return "mach-o section specifier requires a segment and section "
"separated by a comma";

if (Section.size() > 16)
return "mach-o section specifier requires a section whose length is "
"between 1 and 16 characters";

// If there is no comma after the section, we're done.
TAA = 0;
StubSize = 0;
if (Comma.second.empty())
if (SectionType.empty())
return "";

// Otherwise, we need to parse the section type and attributes.
Comma = Comma.second.split(',');

// Get the section type.
StringRef SectionType = Comma.first;
StripSpaces(SectionType);

// Figure out which section type it is.
unsigned TypeID;
for (TypeID = 0; TypeID != MachO::LAST_KNOWN_SECTION_TYPE + 1; ++TypeID)
if (SectionTypeDescriptors[TypeID].AssemblerName &&
SectionType == SectionTypeDescriptors[TypeID].AssemblerName)
break;
auto TypeDescriptor = std::find_if(
std::begin(SectionTypeDescriptors), std::end(SectionTypeDescriptors),
[&](const decltype(*SectionTypeDescriptors) &Descriptor) {
return Descriptor.AssemblerName &&
SectionType == Descriptor.AssemblerName;
});

// If we didn't find the section type, reject it.
if (TypeID > MachO::LAST_KNOWN_SECTION_TYPE)
if (TypeDescriptor == std::end(SectionTypeDescriptors))
return "mach-o section specifier uses an unknown section type";

// Remember the TypeID.
TAA = TypeID;
TAA = TypeDescriptor - std::begin(SectionTypeDescriptors);
TAAParsed = true;

// If we have no comma after the section type, there are no attributes.
if (Comma.second.empty()) {
if (Attrs.empty()) {
// S_SYMBOL_STUBS always require a symbol stub size specifier.
if (TAA == MachO::S_SYMBOL_STUBS)
return "mach-o section specifier of type 'symbol_stubs' requires a size "
"specifier";
return "";
}

// Otherwise, we do have some attributes. Split off the size specifier if
// present.
Comma = Comma.second.split(',');
StringRef Attrs = Comma.first;

// The attribute list is a '+' separated list of attributes.
std::pair<StringRef, StringRef> Plus = Attrs.split('+');

while (1) {
StringRef Attr = Plus.first;
StripSpaces(Attr);

// Look up the attribute.
for (unsigned i = 0; ; ++i) {
if (SectionAttrDescriptors[i].AttrFlag == AttrFlagEnd)
return "mach-o section specifier has invalid attribute";

if (SectionAttrDescriptors[i].AssemblerName &&
Attr == SectionAttrDescriptors[i].AssemblerName) {
TAA |= SectionAttrDescriptors[i].AttrFlag;
break;
}
}

if (Plus.second.empty()) break;
Plus = Plus.second.split('+');
};
SmallVector<StringRef, 1> SectionAttrs;
Attrs.split(SectionAttrs, "+", /*MaxSplit=*/-1, /*KeepEmpty=*/false);

for (StringRef &SectionAttr : SectionAttrs) {
auto AttrDescriptorI = std::find_if(
std::begin(SectionAttrDescriptors), std::end(SectionAttrDescriptors),
[&](const decltype(*SectionAttrDescriptors) &Descriptor) {
return Descriptor.AssemblerName &&
SectionAttr.trim() == Descriptor.AssemblerName;
});
if (AttrDescriptorI == std::end(SectionAttrDescriptors))
return "mach-o section specifier has invalid attribute";

TAA |= AttrDescriptorI->AttrFlag;
}

// Okay, we've parsed the section attributes, see if we have a stub size spec.
if (Comma.second.empty()) {
if (StubSizeStr.empty()) {
// S_SYMBOL_STUBS always require a symbol stub size specifier.
if (TAA == MachO::S_SYMBOL_STUBS)
return "mach-o section specifier of type 'symbol_stubs' requires a size "
Expand All @@ -292,10 +262,6 @@ std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec, // In.
return "mach-o section specifier cannot have a stub size specified because "
"it does not have type 'symbol_stubs'";

// Okay, if we do, it must be a number.
StringRef StubSizeStr = Comma.second;
StripSpaces(StubSizeStr);

// Convert the stub size from a string to an integer.
if (StubSizeStr.getAsInteger(0, StubSize))
return "mach-o section specifier has a malformed stub size";
Expand Down

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