Emit Function IDs table for Control Flow Guard

Adds option /guard:cf to clang-cl and -cfguard to cc1 to emit function IDs
of functions that have their address taken into a section named .gfids$y for
compatibility with Microsoft's Control Flow Guard feature.

Differential Revision: https://reviews.llvm.org/D40531

llvm-svn: 322005

1 files changed, 11 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCWinCOFFStreamer.cpp b/llvm/lib/MC/MCWinCOFFStreamer.cpp
index c2583d95c5e..1f0b64dae73 100644
--- a/llvm/lib/MC/MCWinCOFFStreamer.cpp
+++ b/llvm/lib/MC/MCWinCOFFStreamer.cpp
@@ -193,6 +193,17 @@ void MCWinCOFFStreamer::EmitCOFFSafeSEH(MCSymbol const *Symbol) {
                    << COFF::SCT_COMPLEX_TYPE_SHIFT);
 }
 
+void MCWinCOFFStreamer::EmitCOFFSymbolIndex(MCSymbol const *Symbol) {
+  MCSection *Sec = getCurrentSectionOnly();
+  getAssembler().registerSection(*Sec);
+  if (Sec->getAlignment() < 4)
+    Sec->setAlignment(4);
+
+  new MCSymbolIdFragment(Symbol, getCurrentSectionOnly());
+
+  getAssembler().registerSymbol(*Symbol);
+}
+
 void MCWinCOFFStreamer::EmitCOFFSectionIndex(const MCSymbol *Symbol) {
   visitUsedSymbol(*Symbol);
   MCDataFragment *DF = getOrCreateDataFragment();