commit b0de56b59d1fc77c05c52ab752dc784edf8256d7
author Rafael Espindola <rafael.espindola@gmail.com> Mon Oct 31 21:36:23 2016 +0000
committer Rafael Espindola <rafael.espindola@gmail.com> Mon Oct 31 21:36:23 2016 +0000
tree 5434242c4431b35b090dbbbd7956e604ac90b9f2
parent 75f9d3ac7e442342685432f650a226414b44248b

The expr '.' is not absolute.

With this patch we keep track of the fact that . is a position in the
file and therefore not absolute. This allow us to compute relative
relocations that involve symbol that are defined in linker scripts
with '.'.

This fixes https://llvm.org/bugs/show_bug.cgi?id=30406

There is still more work to track absoluteness over the various
expressions, but this should unblock linking the EFI bootloader.

llvm-svn: 285641

lld/ELF/LinkerScript.cpp

diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp
index 9061dac..6c5fc9e 100644
--- a/lld/ELF/LinkerScript.cpp
+++ b/lld/ELF/LinkerScript.cpp
@@ -299,7 +299,7 @@
     const std::unique_ptr<BaseCommand> &Base1 = *Iter;
     if (auto *Cmd = dyn_cast<SymbolAssignment>(Base1.get())) {
       if (shouldDefine<ELFT>(Cmd))
-        addRegular<ELFT>(Cmd);
+        addSymbol<ELFT>(Cmd);
       continue;
     }
     if (auto *Cmd = dyn_cast<AssertCommand>(Base1.get())) {
@@ -621,7 +621,8 @@
       if (Cmd->Name == ".") {
         Dot = Cmd->Expression(Dot);
       } else if (Cmd->Sym) {
-        cast<DefinedRegular<ELFT>>(Cmd->Sym)->Value = Cmd->Expression(Dot);
+        assignSectionSymbol(Cmd, CurOutSec ? CurOutSec : (*OutputSections)[0],
+                            Dot);
       }
       continue;
     }
@@ -1186,7 +1187,7 @@
   expect("{");
   while (!Error && !consume("}")) {
     StringRef Tok = next();
-    BaseCommand *Cmd = readProvideOrAssignment(Tok, true);
+    BaseCommand *Cmd = readProvideOrAssignment(Tok, false);
     if (!Cmd) {
       if (Tok == "ASSERT")
         Cmd = new AssertCommand(readAssert());
@@ -1636,7 +1637,7 @@
   }
   if (Tok == "CONSTANT") {
     StringRef Name = readParenLiteral();
-    return {[=](uint64_t Dot) { return getConstant(Name); }, true};
+    return [=](uint64_t Dot) { return getConstant(Name); };
   }
   if (Tok == "DEFINED") {
     expect("(");
@@ -1679,23 +1680,20 @@
   }
   if (Tok == "SIZEOF") {
     StringRef Name = readParenLiteral();
-    return {
-        [=](uint64_t Dot) { return ScriptBase->getOutputSectionSize(Name); },
-        true};
+    return [=](uint64_t Dot) { return ScriptBase->getOutputSectionSize(Name); };
   }
   if (Tok == "ALIGNOF") {
     StringRef Name = readParenLiteral();
-    return {
-        [=](uint64_t Dot) { return ScriptBase->getOutputSectionAlign(Name); },
-        true};
+    return
+        [=](uint64_t Dot) { return ScriptBase->getOutputSectionAlign(Name); };
   }
   if (Tok == "SIZEOF_HEADERS")
-    return {[=](uint64_t Dot) { return ScriptBase->getHeaderSize(); }, true};
+    return [=](uint64_t Dot) { return ScriptBase->getHeaderSize(); };
 
   // Tok is a literal number.
   uint64_t V;
   if (readInteger(Tok, V))
-    return {[=](uint64_t Dot) { return V; }, true};
+    return [=](uint64_t Dot) { return V; };
 
   // Tok is a symbol name.
   if (Tok != "." && !isValidCIdentifier(Tok))

lld/ELF/LinkerScript.h

diff --git a/lld/ELF/LinkerScript.h b/lld/ELF/LinkerScript.h
index 5753620..8ab04ab 100644
--- a/lld/ELF/LinkerScript.h
+++ b/lld/ELF/LinkerScript.h
@@ -43,13 +43,9 @@
   uint64_t operator()(uint64_t Dot) const { return Val(Dot); }
   operator bool() const { return (bool)Val; }
 
-  template <typename T>
-  Expr(T Val, std::function<bool()> IsAbsolute)
+  Expr(std::function<uint64_t(uint64_t)> Val, std::function<bool()> IsAbsolute)
       : Val(Val), IsAbsolute(IsAbsolute) {}
-  template <typename T> Expr(T Val, bool IsAbsolute) : Val(Val) {
-    this->IsAbsolute = [=]() { return IsAbsolute; };
-  }
-  template <typename T> Expr(T V) : Expr(V, false) {}
+  template <typename T> Expr(T V) : Expr(V, []() { return true; }) {}
   Expr() : Expr(nullptr) {}
 };