commit b842725c1d8922e0e76de64083f30afbad1bff91
author Michael J. Spencer <bigcheesegs@gmail.com> Tue Apr 17 23:30:05 2018 +0000
committer Michael J. Spencer <bigcheesegs@gmail.com> Tue Apr 17 23:30:05 2018 +0000
tree b7fe7d1685047d191011181f79e02038865b99ce
parent 66f1c9a85816f1fcd4499708defbc94f2a416510

[ELF] Add profile guided section layout

This adds profile guided layout using the Call-Chain Clustering (C³) heuristic
from https://research.fb.com/wp-content/uploads/2017/01/cgo2017-hfsort-final1.pdf .

RFC: [llvm-dev] [RFC] Profile guided section layout
     http://lists.llvm.org/pipermail/llvm-dev/2017-June/114178.html

Pass `--call-graph-ordering-file <file>` to read a call graph profile where each
line has the format:

    <from symbol> <to symbol> <call count>

Differential Revision: https://reviews.llvm.org/D36351

llvm-svn: 330234

lld/ELF/Symbols.cpp

diff --git a/lld/ELF/Symbols.cpp b/lld/ELF/Symbols.cpp
index b932c31..1996400 100644
--- a/lld/ELF/Symbols.cpp
+++ b/lld/ELF/Symbols.cpp
@@ -248,6 +248,27 @@
   message(toString(Sym->File) + S + Sym->getName());
 }
 
+void elf::warnUnorderableSymbol(const Symbol *Sym) {
+  if (!Config->WarnSymbolOrdering)
+    return;
+  const InputFile *File = Sym->File;
+  auto *D = dyn_cast<Defined>(Sym);
+  if (Sym->isUndefined())
+    warn(toString(File) +
+         ": unable to order undefined symbol: " + Sym->getName());
+  else if (Sym->isShared())
+    warn(toString(File) + ": unable to order shared symbol: " + Sym->getName());
+  else if (D && !D->Section)
+    warn(toString(File) +
+         ": unable to order absolute symbol: " + Sym->getName());
+  else if (D && isa<OutputSection>(D->Section))
+    warn(toString(File) +
+         ": unable to order synthetic symbol: " + Sym->getName());
+  else if (D && !D->Section->Repl->Live)
+    warn(toString(File) +
+         ": unable to order discarded symbol: " + Sym->getName());
+}
+
 // Returns a symbol for an error message.
 std::string lld::toString(const Symbol &B) {
   if (Config->Demangle)