Support #pragma clang section directives on MachO targets

rdar://59560986

Differential Revision: https://reviews.llvm.org/D97233

include/llvm/MC/MCSectionMachO.h

@@ -59,14 +59,14 @@ public:
   /// appear after a .section directive in a mach-o flavored .s file.  If
   /// successful, this fills in the specified Out parameters and returns an
   /// empty string.  When an invalid section specifier is present, this returns
-  /// a string indicating the problem. If no TAA was parsed, TAA is not altered,
+  /// an Error indicating the problem. If no TAA was parsed, TAA is not altered,
   /// and TAAWasSet becomes false.
-  static std::string ParseSectionSpecifier(StringRef Spec,       // In.
+  static Error ParseSectionSpecifier(StringRef Spec,      // In.
-                                           StringRef &Segment,   // Out.
+                                     StringRef &Segment,  // Out.
-                                           StringRef &Section,   // Out.
+                                     StringRef &Section,  // Out.
-                                           unsigned  &TAA,       // Out.
+                                     unsigned &TAA,       // Out.
-                                           bool      &TAAParsed, // Out.
+                                     bool &TAAParsed,     // Out.
-                                           unsigned  &StubSize); // Out.
+                                     unsigned &StubSize); // Out.
 
   void PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
                             raw_ostream &OS,

lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -1129,13 +1129,12 @@ void TargetLoweringObjectFileMachO::emitModuleMetadata(MCStreamer &Streamer,
   StringRef Segment, Section;
   unsigned TAA = 0, StubSize = 0;
   bool TAAParsed;
-  std::string ErrorCode =
+  if (Error E = MCSectionMachO::ParseSectionSpecifier(
-    MCSectionMachO::ParseSectionSpecifier(SectionVal, Segment, Section,
+          SectionVal, Segment, Section, TAA, TAAParsed, StubSize)) {
-                                          TAA, TAAParsed, StubSize);
-  if (!ErrorCode.empty())
     // If invalid, report the error with report_fatal_error.
-    report_fatal_error("Invalid section specifier '" + Section + "': " +
+    report_fatal_error("Invalid section specifier '" + Section +
-                       ErrorCode + ".");
+                       "': " + toString(std::move(E)) + ".");
+  }
 
   // Get the section.
   MCSectionMachO *S = getContext().getMachOSection(
@@ -1159,6 +1158,14 @@ static void checkMachOComdat(const GlobalValue *GV) {
 
 MCSection *TargetLoweringObjectFileMachO::getExplicitSectionGlobal(
     const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
+
+  StringRef SectionName = GO->getSection();
+
+  const Function *F = dyn_cast<Function>(GO);
+  if (F && F->hasFnAttribute("implicit-section-name")) {
+    SectionName = F->getFnAttribute("implicit-section-name").getValueAsString();
+  }
+
   // Parse the section specifier and create it if valid.
   StringRef Segment, Section;
   unsigned TAA = 0, StubSize = 0;
@@ -1166,14 +1173,12 @@ MCSection *TargetLoweringObjectFileMachO::getExplicitSectionGlobal(
 
   checkMachOComdat(GO);
 
-  std::string ErrorCode =
+  if (Error E = MCSectionMachO::ParseSectionSpecifier(
-    MCSectionMachO::ParseSectionSpecifier(GO->getSection(), Segment, Section,
+          SectionName, Segment, Section, TAA, TAAParsed, StubSize)) {
-                                          TAA, TAAParsed, StubSize);
-  if (!ErrorCode.empty()) {
     // If invalid, report the error with report_fatal_error.
     report_fatal_error("Global variable '" + GO->getName() +
                        "' has an invalid section specifier '" +
-                       GO->getSection() + "': " + ErrorCode + ".");
+                       GO->getSection() + "': " + toString(std::move(E)) + ".");
   }
 
   // Get the section.

lib/MC/MCParser/DarwinAsmParser.cpp

@@ -23,6 +23,7 @@
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/MC/SectionKind.h"
+#include "llvm/Support/Error.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/SMLoc.h"
@@ -689,12 +690,9 @@ bool DarwinAsmParser::parseDirectiveSection(StringRef, SMLoc) {
   unsigned StubSize;
   unsigned TAA;
   bool TAAParsed;
-  std::string ErrorStr =
+  if (class Error E = MCSectionMachO::ParseSectionSpecifier(
-    MCSectionMachO::ParseSectionSpecifier(SectionSpec, Segment, Section,
+          SectionSpec, Segment, Section, TAA, TAAParsed, StubSize))
-                                          TAA, TAAParsed, StubSize);
+    return Error(Loc, toString(std::move(E)));
-
-  if (!ErrorStr.empty())
-    return Error(Loc, ErrorStr);
 
   // Issue a warning if the target is not powerpc and Section is a *coal* section.
   Triple TT = getParser().getContext().getObjectFileInfo()->getTargetTriple();

lib/MC/MCSectionMachO.cpp

@@ -174,12 +174,12 @@ bool MCSectionMachO::isVirtualSection() const {
 /// flavored .s file.  If successful, this fills in the specified Out
 /// parameters and returns an empty string.  When an invalid section
 /// specifier is present, this returns a string indicating the problem.
-std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec,        // In.
+Error MCSectionMachO::ParseSectionSpecifier(StringRef Spec,       // In.
-                                                  StringRef &Segment,    // Out.
+                                            StringRef &Segment,   // Out.
-                                                  StringRef &Section,    // Out.
+                                            StringRef &Section,   // Out.
-                                                  unsigned  &TAA,        // Out.
+                                            unsigned &TAA,        // Out.
-                                                  bool      &TAAParsed,  // Out.
+                                            bool &TAAParsed,      // Out.
-                                                  unsigned  &StubSize) { // Out.
+                                            unsigned &StubSize) { // Out.
   TAAParsed = false;
 
   SmallVector<StringRef, 5> SplitSpec;
@@ -194,25 +194,23 @@ std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec,        // In.
   StringRef Attrs = GetEmptyOrTrim(3);
   StringRef StubSizeStr = GetEmptyOrTrim(4);
 
-  // Verify that the segment is present and not too long.
+  // Verify that the section is present.
-  if (Segment.empty() || Segment.size() > 16)
-    return "mach-o section specifier requires a segment whose length is "
-           "between 1 and 16 characters";
-
-  // Verify that the section is present and not too long.
   if (Section.empty())
-    return "mach-o section specifier requires a segment and section "
+    return createStringError(inconvertibleErrorCode(),
-           "separated by a comma";
+                             "mach-o section specifier requires a segment "
+                             "and section separated by a comma");
 
+  // Verify that the section is not too long.
   if (Section.size() > 16)
-    return "mach-o section specifier requires a section whose length is "
+    return createStringError(inconvertibleErrorCode(),
-           "between 1 and 16 characters";
+                             "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 (SectionType.empty())
-    return "";
+    return Error::success();
 
   // Figure out which section type it is.
   auto TypeDescriptor =
@@ -223,7 +221,9 @@ std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec,        // In.
 
   // If we didn't find the section type, reject it.
   if (TypeDescriptor == std::end(SectionTypeDescriptors))
-    return "mach-o section specifier uses an unknown section type";
+    return createStringError(inconvertibleErrorCode(),
+                             "mach-o section specifier uses an unknown "
+                             "section type");
 
   // Remember the TypeID.
   TAA = TypeDescriptor - std::begin(SectionTypeDescriptors);
@@ -233,9 +233,10 @@ std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec,        // In.
   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 "
+      return createStringError(inconvertibleErrorCode(),
-             "specifier";
+                               "mach-o section specifier of type "
-    return "";
+                               "'symbol_stubs' requires a size specifier");
+    return Error::success();
   }
 
   // The attribute list is a '+' separated list of attributes.
@@ -249,7 +250,9 @@ std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec,        // In.
                         return SectionAttr.trim() == Descriptor.AssemblerName;
                       });
     if (AttrDescriptorI == std::end(SectionAttrDescriptors))
-      return "mach-o section specifier has invalid attribute";
+      return createStringError(inconvertibleErrorCode(),
+                               "mach-o section specifier has invalid "
+                               "attribute");
 
     TAA |= AttrDescriptorI->AttrFlag;
   }
@@ -258,19 +261,24 @@ std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec,        // In.
   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 "
+      return createStringError(inconvertibleErrorCode(),
-      "specifier";
+                               "mach-o section specifier of type "
-    return "";
+                               "'symbol_stubs' requires a size specifier");
+    return Error::success();
   }
 
   // If we have a stub size spec, we must have a sectiontype of S_SYMBOL_STUBS.
   if ((TAA & MachO::SECTION_TYPE) != MachO::S_SYMBOL_STUBS)
-    return "mach-o section specifier cannot have a stub size specified because "
+    return createStringError(inconvertibleErrorCode(),
-           "it does not have type 'symbol_stubs'";
+                             "mach-o section specifier cannot have a stub "
+                             "size specified because it does not have type "
+                             "'symbol_stubs'");
 
   // 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";
+    return createStringError(inconvertibleErrorCode(),
+                             "mach-o section specifier has a malformed "
+                             "stub size");
 
-  return "";
+  return Error::success();
 }

lib/Transforms/Instrumentation/AddressSanitizer.cpp

@@ -1919,9 +1919,8 @@ bool ModuleAddressSanitizer::shouldInstrumentGlobal(GlobalVariable *G) const {
       StringRef ParsedSegment, ParsedSection;
       unsigned TAA = 0, StubSize = 0;
       bool TAAParsed;
-      std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
+      cantFail(MCSectionMachO::ParseSectionSpecifier(
-          Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
+          Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize));
-      assert(ErrorCode.empty() && "Invalid section specifier.");
 
       // Ignore the globals from the __OBJC section. The ObjC runtime assumes
       // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to

test/CodeGen/AArch64/clang-section-macho.ll

@@ -0,0 +1,11 @@
+;RUN: llc -mtriple=arm64-apple-ios %s -o - | FileCheck %s
+
+define dso_local void @foo() #0 {
+entry:
+  ret void
+}
+
+attributes #0 = { "implicit-section-name"="__TEXT,__mytext" }
+
+; CHECK:      .section	__TEXT,__mytext
+; CHECK-NEXT: .globl	_foo