[ELF] - Support "INSERT AFTER" statement.

This implements INSERT AFTER in a following way:

During reading scripts it collects all insert statements.
After we done and read all files it inserts statements into script commands list.

With that:
* Rest of code does know nothing about INSERT.
* Approach is straightforward and have no visible limitations.
* It is also easy to support INSERT BEFORE (was seen in clang code once).
* Should work for PR35877 and similar cases.

Cons:
* It assumes we have "main" scripts that describes sections.

Differential revision: https://reviews.llvm.org/D43468

llvm-svn: 327003

1 files changed, 7 insertions, 0 deletions

diff --git a/lld/ELF/LinkerScript.h b/lld/ELF/LinkerScript.h
index 4eddafa4996..fe5d6d8ef6f 100644
--- a/lld/ELF/LinkerScript.h
+++ b/lld/ELF/LinkerScript.h
@@ -267,6 +267,9 @@ public:
   void processSectionCommands();
   void declareSymbols();
 
+  // Used to handle INSERT AFTER statements.
+  void processInsertCommands();
+
   // SECTIONS command list.
   std::vector<BaseCommand *> SectionCommands;
 
@@ -285,6 +288,10 @@ public:
 
   // A list of symbols referenced by the script.
   std::vector<llvm::StringRef> ReferencedSymbols;
+
+  // Used to implement INSERT AFTER. Contains commands that need
+  // to be inserted into SECTIONS commands list.
+  llvm::DenseMap<StringRef, std::vector<BaseCommand *>> InsertAfterCommands;
 };
 
 extern LinkerScript *Script;