[ELF] Support INSERT [AFTER|BEFORE] for orphan sections

[MaskRay]

Summary

D43468+D44380 added INSERT [AFTER|BEFORE] for non-orphan sections. This patch
makes INSERT work for orphan sections as well.

SECTIONS {...} INSERT [AFTER|BEFORE] .foo does not set hasSectionCommands, so the result
will be similar to a regular link without a linker script. The differences when hasSectionCommands is set include:

• image base is different
• -z noseparate-code/-z noseparate-loadable-segments are unavailable
• some special symbols such as _end _etext _edata are not defined

The behavior is similar to GNU ld:
INSERT is not considered an external linker script.

This feature makes the section layout more flexible. It can be used to:

• Place .nv_fatbin before other readonly SHT_PROGBITS sections to mitigate relocation overflows.
• Disturb the layout to expose address sensitive application bugs.

[MaskRay]

lld/ELF/ScriptParser.cpp

561

In the future, we should stop enforcing --no-rosegment for hasSectionsCommand so that features can be more orthogonal. (I've mentioned this many times to Android/FreeBSD folks...)

[grimar]

lld/ELF/LinkerScript.cpp

248–249

Seems the comment needs an update to mention "BEFORE".

251–252

Don't use auto then?

252–256

I am not sure this is a clear comment. I had to read the code to understand what you do.
Perhaps it should say something like "we do not handle an INSERT command for an output section that ...."

283

The using of curly bracers violates the LLD style a bit. Across it's code we usually added an additional
brackets for each case where a branch contained more than a single line. I.e.:

for (auto it = sectionCommands.begin(), e = sectionCommands.end(); it != e;
     ++it) {
  if (auto *to = dyn_cast<OutputSection>(*it)) {
    if (to->name == where) {
      if (isAfter)
        ++it;
      sectionCommands.insert(it, os);
      found = true;
      break;
    }
  }
}

To clarify: here you have bracers in a internal branch, hence parent branches expected to use them too.
Actually I probably like this rule, but I observed many times that in LLVM people not always follow it.
And seems there is nothing like that in LLVM coding standart document. So seems it was something internal to LLD,
but perhaps it is better to follow for consistency with the rest od the code?

lld/ELF/LinkerScript.h

322

What do you think about adding a named struct instead of using the tuple (see PhdrsCommand/AddressState above).

lld/test/ELF/linkerscript/insert-after.test

54

BEFORE -> AFTER

55

Please clarify/expand what is "without making more layout changes". I think usually the word "layout" is commonly used
to describe the layout of sections. But here the order of them is the same, the difference is in segments created, though the first
comment says nothing about that, it is a bit hard to understand what is actually the difference I think.

Perhaps you could also combine the testing of section names to emphasise the difference (i.e. use something like --check-prefixes=COMMON,PART1 --check-prefixes=COMMON,PART2). Up to you though.

lld/test/ELF/linkerscript/insert-duplicate.test

7

Lets add a general description of the test case?

21

Could you expand this comment and below ones please.

[pohlen]

Thanks for implementing this so quickly! Looks good to my untrained eyes :)

lld/ELF/LinkerScript.cpp

273–283

I find this a bit difficult to read because of the nested statements. Maybe we can flatten it using llvm::find?

auto insertPos = llvm::find_if(sectionCommands, [where](BaseCommand *command) {
  auto *to = dyn_cast<OutputSection>(*it);
  return to != nullptr && to->name == where;
});

if (insertPos == sectionCommands.end())
  error("unable to insert " + os->name +
        Twine(isAfter ? " after " : " before ") + where);

if (isAfter)
  ++insertPos;

sectionCommands.insert(insertPos, os);

Up to you. Feel free to leave as is.

lld/ELF/ScriptParser.cpp

571

[nit]: Move declaration to initialization?

StringRef where = next();

[psmith]

lld/ELF/LinkerScript.h

322

FWIW I'd tend towards using a named struct here. We have to look down to the bit of code to find out what the fields are.

OutputSection *os;
bool isAfter;
StringRef where;
std::tie(os, isAfter, where) = insert;

lld/ELF/ScriptParser.cpp

561

Perhaps the intention can be added to the release notes for 10.0. For example in LLD 11.0 we intend to make the following changes:

• a linker script no longer implies --no-rosegment

This might be some way towards informing users of interface changes so that they don't get surprised. Given that few read the release notes, we might also consider a warning, maybe an optional one if someone uses a feature that will have its default changed.

[MaskRay]

Address comments

[MaskRay]

lld/ELF/LinkerScript.cpp

273–283

Thanks. I agree find_if makes the code easier to read.

283

I also prefer fewer braces. (Excess braces harm readability to me...). In Writer.cpp, we have such code:

// Writer.cpp
    for (Symbol *sym : symtab->symbols())
      if (sym->isUndefined() && !sym->isWeak())
        if (auto *f = dyn_cast_or_null<SharedFile>(sym->file))
          if (f->allNeededIsKnown)
            error(toString(f) + ": undefined reference to " + toString(*sym));

I know that in some places, we added braces just to make it harder to make misleading indentation errors. However, -Wmisleading-indentation (GCC 6, clang 10) makes such protection more or less unnecessary...

lld/test/ELF/linkerscript/insert-after.test

55

Address/offset assignments are different with a SECTIONS command. They can be seen from the CHECK/CHECK2 lines.

I added a sentence Address/offset assignments are different with a main linker script. to emphasize this fact.

[pohlen]

Thanks! LGTM

[psmith]

Thanks for the update, I'm fine with this as well.

[grimar]

LGTM too.

[MaskRay]

lld/ELF/ScriptParser.cpp

565

@srhines @nickdesaulniers I want to delete config->singleRoRx = true; in the future to be more consistant with other parts of lld. (It also matches ld.bfd -z separate-code)

Can you please test whether any project needs adaptation with this change?

[nickdesaulniers]

lld/ELF/ScriptParser.cpp

565

Sorry, what is the ask? I don't see separate-code being used in the Linux kernel. Or are you asking about all of Android (userspace)?

[MaskRay]

lld/ELF/ScriptParser.cpp

565

I'm asking about all of Android userspace that may use the linker script SECTIONS command.

Currently, due to config->singleRoRx = true; (like enforced --no-rosegment), there is no R PT_LOAD segment with a SECTIONS command.

After deleting config->singleRoRx = true;, an executable with a SECTIONS command will get one R PT_LOAD segment and one RX PT_LOAD segment, like a regular executable without a linker script.

I don't expect it will affect Linux kernel. We can easily add --no-rosegment if it does.

[srhines]

lld/ELF/ScriptParser.cpp

565

We'll likely be able to check this out with our next update. If we hit problems, we can follow up. Thanks for letting me know.

lld/ELF/Driver.cpp

template <class ELFT> void LinkerDriver::link(opt::InputArgList &args) {
   if (!bitcodeFiles.empty())
     for (auto *s : lto::LTO::getRuntimeLibcallSymbols())
       handleLibcall(s);
 
   // Return if there were name resolution errors.
   if (errorCount())
     return;
 
-  // Now when we read all script files, we want to finalize order of linker
-  // script commands, which can be not yet final because of INSERT commands.
-  script->processInsertCommands();
-
   // We want to declare linker script's symbols early,
   // so that we can version them.
   // They also might be exported if referenced by DSOs.
   script->declareSymbols();
 
   // Handle the -exclude-libs option.
   if (args.hasArg(OPT_exclude_libs))
     excludeLibs(args);

lld/ELF/LinkerScript.h

struct ByteCommand : BaseCommand {
 
   // This is just an offset of this assignment command in the output section.
   unsigned offset;
 
   // Size of this data command.
   unsigned size;
 };
 
+struct InsertCommand {
+  OutputSection *os;
+  bool isAfter;
+  StringRef where;
+};
+
 struct PhdrsCommand {
   StringRef name;
   unsigned type = llvm::ELF::PT_NULL;
   bool hasFilehdr = false;
   bool hasPhdrs = false;
   llvm::Optional<unsigned> flags;
   Expr lmaExpr = nullptr;
 };
public:
   std::vector<InputSectionDescription *> keptSections;
 
   // A map from memory region name to a memory region descriptor.
   llvm::MapVector<llvm::StringRef, MemoryRegion *> memoryRegions;
 
   // A list of symbols referenced by the script.
   std::vector<llvm::StringRef> referencedSymbols;
 
-  // Used to implement INSERT [AFTER|BEFORE]. Contains commands that need
-  // to be inserted into SECTIONS commands list.
-  llvm::DenseMap<StringRef, std::vector<BaseCommand *>> insertAfterCommands;
-  llvm::DenseMap<StringRef, std::vector<BaseCommand *>> insertBeforeCommands;
+  // Used to implement INSERT [AFTER|BEFORE]. Contains output sections that need
+  // to be reordered.
+  std::vector<InsertCommand> insertCommands;
 };
 
 extern LinkerScript *script;
 
 } // end namespace elf
 } // end namespace lld
 
 #endif // LLD_ELF_LINKER_SCRIPT_H

lld/ELF/LinkerScript.cpp

getChangedSymbolAssignment(const SymbolAssignmentMap &oldValues) {
   for (auto &it : oldValues) {
     const Defined *sym = it.first;
     if (std::make_pair(sym->section, sym->value) != it.second &&
         (!changed || sym->getName() < changed->getName()))
       changed = sym;
   }
   return changed;
 }
 
-// This method is used to handle INSERT AFTER statement. Here we rebuild
-// the list of script commands to mix sections inserted into.
+// Process INSERT [AFTER|BEFORE] commands. For each command, we move the
+// specified output section to the designated place.
 void LinkerScript::processInsertCommands() {
-  std::vector<BaseCommand *> v;
-  auto insert = [&](std::vector<BaseCommand *> &from) {
-    v.insert(v.end(), from.begin(), from.end());
-    from.clear();
-  };
-
-  for (BaseCommand *base : sectionCommands) {
-    if (auto *os = dyn_cast<OutputSection>(base)) {
-      insert(insertBeforeCommands[os->name]);
-      v.push_back(base);
-      insert(insertAfterCommands[os->name]);
+  for (const InsertCommand &cmd : insertCommands) {
+    // If cmd.os is empty, it may have been discarded by
+    // adjustSectionsBeforeSorting(). We do not handle such output sections.
+    auto from = llvm::find(sectionCommands, cmd.os);
+    if (from == sectionCommands.end())
       continue;
+    sectionCommands.erase(from);
+
+    auto insertPos = llvm::find_if(sectionCommands, [&cmd](BaseCommand *base) {
+      auto *to = dyn_cast<OutputSection>(base);
+      return to != nullptr && to->name == cmd.where;
+    });
+    if (insertPos == sectionCommands.end()) {
+      error("unable to insert " + cmd.os->name +
+            (cmd.isAfter ? " after " : " before ") + cmd.where);
+    } else {
+      if (cmd.isAfter)
+        ++insertPos;
+      sectionCommands.insert(insertPos, cmd.os);
     }
-    v.push_back(base);
   }
-
-  for (auto &cmds : {insertBeforeCommands, insertAfterCommands})
-    for (const std::pair<StringRef, std::vector<BaseCommand *>> &p : cmds)
-      if (!p.second.empty())
-        error("unable to INSERT AFTER/BEFORE " + p.first +
-              ": section not defined");
-
-  sectionCommands = std::move(v);
 }
 
 // Symbols defined in script should not be inlined by LTO. At the same time
 // we don't know their final values until late stages of link. Here we scan
 // over symbol assignment commands and create placeholder symbols if needed.
 void LinkerScript::declareSymbols() {
   assert(!ctx);
   for (BaseCommand *base : sectionCommands) {
     if (auto *cmd = dyn_cast<SymbolAssignment>(base)) {
       declareSymbol(cmd);
       continue;
     }
 
     // If the output section directive has constraints,
     // we can't say for sure if it is going to be included or not.
     // Skip such sections for now. Improve the checks if we ever
     // need symbols from that sections to be declared early.
     auto *sec = cast<OutputSection>(base);
     if (sec->constraint != ConstraintKind::NoConstraint)

lld/ELF/ScriptParser.cpp

for (BaseCommand *cmd : v)
       max = std::max(max, cast<OutputSection>(cmd)->size);
     return addrExpr().getValue() + max;
   };
   v.push_back(make<SymbolAssignment>(".", moveDot, getCurrentLocation()));
   return v;
 }
 
 void ScriptParser::readSections() {
-  script->hasSectionsCommand = true;
-
-  // -no-rosegment is used to avoid placing read only non-executable sections in
-  // their own segment. We do the same if SECTIONS command is present in linker
-  // script. See comment for computeFlags().
-  config->singleRoRx = true;
-
   expect("{");
   std::vector<BaseCommand *> v;
   while (!errorCount() && !consume("}")) {
     StringRef tok = next();
     if (tok == "OVERLAY") {
       for (BaseCommand *cmd : readOverlay())
         v.push_back(cmd);
       continue;
     } else if (tok == "INCLUDE") {
       readInclude();
       continue;
     }
 
     if (BaseCommand *cmd = readAssignment(tok))
       v.push_back(cmd);
     else
       v.push_back(readOutputSectionDescription(tok));
   }
+  script->sectionCommands.insert(script->sectionCommands.end(), v.begin(),
+                                 v.end());
 
-  if (!atEOF() && consume("INSERT")) {
-    std::vector<BaseCommand *> *dest = nullptr;
-    if (consume("AFTER"))
-      dest = &script->insertAfterCommands[next()];
-    else if (consume("BEFORE"))
-      dest = &script->insertBeforeCommands[next()];
-    else
-      setError("expected AFTER/BEFORE, but got '" + next() + "'");
-    if (dest)
-      dest->insert(dest->end(), v.begin(), v.end());
+  if (atEOF() || !consume("INSERT")) {
+    // --no-rosegment is used to avoid placing read only non-executable sections
+    // in their own segment. We do the same if SECTIONS command is present in
+    // linker script. See comment for computeFlags().
+    // TODO This rule will be dropped in the future.
+    config->singleRoRx = true;
+
+    script->hasSectionsCommand = true;
     return;
   }
 
-  script->sectionCommands.insert(script->sectionCommands.end(), v.begin(),
-                                 v.end());
+  bool isAfter = false;
+  if (consume("AFTER"))
+    isAfter = true;
+  else if (!consume("BEFORE"))
+    setError("expected AFTER/BEFORE, but got '" + next() + "'");
+  StringRef where = next();
+  for (BaseCommand *cmd : v)
+    if (auto *os = dyn_cast<OutputSection>(cmd))
+      script->insertCommands.push_back({os, isAfter, where});
 }
 
 void ScriptParser::readTarget() {
   // TARGET(foo) is an alias for "--format foo". Unlike GNU linkers,
   // we accept only a limited set of BFD names (i.e. "elf" or "binary")
   // for --format. We recognize only /^elf/ and "binary" in the linker
   // script as well.
   expect("(");
   StringRef tok = next();
   expect(")");
 
   if (tok.startswith("elf"))
     config->formatBinary = false;

lld/ELF/Writer.cpp

template <class ELFT> void Writer<ELFT>::sortSections() {
 
   if (!script->hasSectionsCommand) {
     // We know that all the OutputSections are contiguous in this case.
     auto isSection = [](BaseCommand *base) { return isa<OutputSection>(base); };
     std::stable_sort(
         llvm::find_if(script->sectionCommands, isSection),
         llvm::find_if(llvm::reverse(script->sectionCommands), isSection).base(),
         compareSections);
+
+    // Process INSERT commands. From this point onwards the order of
+    // script->sectionCommands is fixed.
+    script->processInsertCommands();
     return;
   }
 
+  script->processInsertCommands();
+
   // Orphan sections are sections present in the input files which are
   // not explicitly placed into the output file by the linker script.
   //
   // The sections in the linker script are already in the correct
   // order. We have to figuere out where to insert the orphan
   // sections.
   //
   // The order of the sections in the script is arbitrary and may not agree with

lld/test/ELF/linkerscript/insert-after.test

 # REQUIRES: x86
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/insert-after.s -o %t1.o
 
 ## Main linker script contains .text and .data sections. Here
 ## we check that can use INSERT AFTER to insert sections .foo.data
 ## and .foo.text at the right places.
 
-SECTIONS {
-  .foo.data : { *(.foo.data) }
-} INSERT AFTER .data;
-
-SECTIONS {
-  .foo.text : { *(.foo.text) }
-} INSERT AFTER .text;
-
 # RUN: ld.lld %t1.o -o %t1 --script %p/Inputs/insert-after.script --script %s
-# RUN: llvm-objdump -section-headers %t1 | FileCheck %s
-# CHECK:      Sections:
-# CHECK-NEXT: Idx Name          Size     VMA              Type
-# CHECK-NEXT:   0               00000000 0000000000000000
-# CHECK-NEXT:   1 .text         00000008 0000000000000000 TEXT
-# CHECK-NEXT:   2 .foo.text     00000008 0000000000000008 TEXT
-# CHECK-NEXT:   3 .data         00000008 0000000000000010 DATA
-# CHECK-NEXT:   4 .foo.data     00000008 0000000000000018 DATA
-
-# RUN: not ld.lld %t1.o -o %t1 --script %s 2>&1 \
-# RUN:   | FileCheck %s --check-prefix=ERR
-# ERR-DAG: error: unable to INSERT AFTER/BEFORE .text: section not defined
-# ERR-DAG: error: unable to INSERT AFTER/BEFORE .data: section not defined
+# RUN: llvm-readelf -S -l %t1 | FileCheck %s
+# CHECK:      Name      Type     Address          Off
+# CHECK-NEXT:           NULL     0000000000000000 000000
+# CHECK-NEXT: .text     PROGBITS 0000000000000000 001000
+# CHECK-NEXT: .foo.text PROGBITS 0000000000000008 001008
+# CHECK-NEXT: .data     PROGBITS 0000000000000010 001010
+# CHECK-NEXT: .foo.data PROGBITS 0000000000000018 001018
+# CHECK:      Type
+# CHECK-NEXT: LOAD {{.*}} R E
+# CHECK-NEXT: LOAD {{.*}} RW
+# CHECK-NEXT: GNU_STACK {{.*}} RW
+
+## There is no main linker script. INSERT AFTER just reorders output sections,
+## without making more layout changes. Address/offset assignments are different
+## with a main linker script.
+
+# RUN: ld.lld --script %s %t1.o -o %t2
+# RUN: llvm-readelf -S -l %t2 | FileCheck --check-prefix=CHECK2 %s
+# CHECK2:      Name      Type     Address          Off
+# CHECK2-NEXT:           NULL     0000000000000000 000000
+# CHECK2-NEXT: .text     PROGBITS 0000000000201158 000158
+# CHECK2-NEXT: .foo.text PROGBITS 0000000000201160 000160
+# CHECK2-NEXT: .data     PROGBITS 0000000000202168 000168
+# CHECK2-NEXT: .foo.data PROGBITS 0000000000202170 000170
+# CHECK2:      Type
+# CHECK2-NEXT: PHDR {{.*}} R
+# CHECK2-NEXT: LOAD {{.*}} R
+# CHECK2-NEXT: LOAD {{.*}} R E
+# CHECK2-NEXT: LOAD {{.*}} RW
+# CHECK2-NEXT: GNU_STACK {{.*}} RW
+
+SECTIONS { .foo.data : { *(.foo.data) } } INSERT AFTER .data;
+
+## The input section .foo.text is an orphan. It will be placed in .foo.text
+SECTIONS { .foo.text : {} } INSERT AFTER .text;

lld/test/ELF/linkerscript/insert-before.test

 # REQUIRES: x86
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/insert-after.s -o %t1.o
 
 ## Main linker script contains .text and .data sections. Here
 ## we check that can use INSERT BEFORE to insert sections .foo.data
 ## and .foo.text at the right places.
 
-SECTIONS {
-  .foo.data : { *(.foo.data) }
-} INSERT BEFORE .data;
-
-SECTIONS {
-  .foo.text : { *(.foo.text) }
-} INSERT BEFORE .text;
-
 # RUN: ld.lld %t1.o -o %t1 --script %p/Inputs/insert-after.script --script %s
-# RUN: llvm-objdump -section-headers %t1 | FileCheck %s
-# CHECK:      Sections:
-# CHECK-NEXT: Idx Name          Size     VMA         Type
-# CHECK-NEXT:   0               00000000 0000000000000000
-# CHECK-NEXT:   1 .foo.text     00000008 0000000000000000 TEXT
-# CHECK-NEXT:   2 .text         00000008 0000000000000008 TEXT
-# CHECK-NEXT:   3 .foo.data     00000008 0000000000000010 DATA
-# CHECK-NEXT:   4 .data         00000008 0000000000000018 DATA
-
-# RUN: not ld.lld %t1.o -o %t1 --script %s 2>&1 \
-# RUN:   | FileCheck %s --check-prefix=ERR
-# ERR-DAG: error: unable to INSERT AFTER/BEFORE .text: section not defined
-# ERR-DAG: error: unable to INSERT AFTER/BEFORE .data: section not defined
+# RUN: llvm-readelf -S -l %t1 | FileCheck %s
+# CHECK:      Name      Type     Address          Off
+# CHECK-NEXT:           NULL     0000000000000000 000000
+# CHECK-NEXT: .foo.text PROGBITS 0000000000000000 001000
+# CHECK-NEXT: .text     PROGBITS 0000000000000008 001008
+# CHECK-NEXT: .foo.data PROGBITS 0000000000000010 001010
+# CHECK-NEXT: .data     PROGBITS 0000000000000018 001018
+# CHECK:      Type
+# CHECK-NEXT: LOAD {{.*}} R E
+# CHECK-NEXT: LOAD {{.*}} RW
+# CHECK-NEXT: GNU_STACK {{.*}} RW
+
+## There is no main linker script. INSERT BEFORE just reorders output sections,
+## without making more layout changes. Address/offset assignments are different
+## with a main linker script.
+
+# RUN: ld.lld --script %s %t1.o -o %t2
+# RUN: llvm-readelf -S -l %t2 | FileCheck --check-prefix=CHECK2 %s
+# CHECK2:      Name      Type     Address          Off
+# CHECK2-NEXT:           NULL     0000000000000000 000000
+# CHECK2-NEXT: .foo.text PROGBITS 0000000000201158 000158
+# CHECK2-NEXT: .text     PROGBITS 0000000000201160 000160
+# CHECK2-NEXT: .foo.data PROGBITS 0000000000202168 000168
+# CHECK2-NEXT: .data     PROGBITS 0000000000202170 000170
+# CHECK2:      Type
+# CHECK2-NEXT: PHDR {{.*}} R
+# CHECK2-NEXT: LOAD {{.*}} R
+# CHECK2-NEXT: LOAD {{.*}} R E
+# CHECK2-NEXT: LOAD {{.*}} RW
+
+SECTIONS { .foo.data : { *(.foo.data) } } INSERT BEFORE .data;
+
+## The input section .foo.text is an orphan. It will be placed in .foo.text
+SECTIONS { .foo.text : {} } INSERT BEFORE .text;

lld/test/ELF/linkerscript/insert-duplicate.test

+# REQUIRES: x86
+## Test that we can handle cases where an output section is specified by multiple
+## INSERT commands. Each output section description creates a new instance.
+## A redundant description matches no input sections and thus is a no-op.
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64 %p/Inputs/insert-after.s -o %t.o
+# RUN: ld.lld -T %s %t.o -o %t
+# RUN: llvm-readelf -S -l %t | FileCheck %s
+
+# CHECK:      Name      Type     Address          Off
+# CHECK-NEXT:           NULL     0000000000000000 000000
+# CHECK-NEXT: .text     PROGBITS 00000000002011c8 0001c8
+# CHECK-NEXT: .foo.data PROGBITS 00000000002021d0 0001d0
+# CHECK-NEXT: .foo.text PROGBITS 00000000002031d8 0001d8
+# CHECK:      Type
+# CHECK-NEXT: PHDR {{.*}} R
+# CHECK-NEXT: LOAD {{.*}} R
+# CHECK-NEXT: LOAD {{.*}} R E
+# CHECK-NEXT: LOAD {{.*}} RW
+# CHECK-NEXT: LOAD {{.*}} R E
+# CHECK-NEXT: LOAD {{.*}} RW
+# CHECK-NEXT: GNU_STACK {{.*}} RW
+
+## First, move .foo.data after .foo.text
+SECTIONS { .foo.data : { *(.foo.data) } } INSERT AFTER .foo.text;
+
+## Next, move .foo.text after .foo.data
+SECTIONS { .foo.text : { *(.foo.text) } } INSERT AFTER .foo.data;
+
+## No-op. The .foo.data output section is a different instance and matches no
+## input sections.
+SECTIONS { .foo.data : { *(.foo.data) } } INSERT AFTER .foo.text;

lld/test/ELF/linkerscript/insert-not-exist.test

+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64 %p/Inputs/insert-after.s -o %t.o
+# RUN: not ld.lld -T %s %t.o 2>&1 | FileCheck %s
+
+# CHECK: error: unable to insert .foo.data after .not_exist
+# CHECK: error: unable to insert .foo.text before .not_exist
+
+SECTIONS { .foo.data : {} } INSERT AFTER .not_exist;
+SECTIONS { .foo.text : {} } INSERT BEFORE .not_exist;