Fix pr24486.

This extends the work done in r233995 so that now getFragment (in addition to
getSection) also works for variable symbols.

With that the existing logic to decide if a-b can be computed works even if
a or b are variables. Given that, the expression evaluation can avoid expanding
variables as aggressively and that in turn lets the relocation code see the
original variable.

In order for this to work with the asm streamer, there is now a dummy fragment
per section. It is used to assign a section to a symbol when no other fragment
exists.

This patch is a joint work by Maxim Ostapenko andy myself.

llvm-svn: 249303

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
index 7a30075bac9..f9dbd5ad3f0 100644
--- a/llvm/lib/MC/MCAsmStreamer.cpp
+++ b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -575,7 +575,7 @@ void MCAsmStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
 void MCAsmStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
                                  uint64_t Size, unsigned ByteAlignment) {
   if (Symbol)
-    AssignSection(Symbol, Section);
+    AssignFragment(Symbol, &Section->getDummyFragment());
 
   // Note: a .zerofill directive does not switch sections.
   OS << ".zerofill ";
@@ -599,7 +599,7 @@ void MCAsmStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
 // e.g. _a.
 void MCAsmStreamer::EmitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
                                    uint64_t Size, unsigned ByteAlignment) {
-  AssignSection(Symbol, Section);
+  AssignFragment(Symbol, &Section->getDummyFragment());
 
   assert(Symbol && "Symbol shouldn't be NULL!");
   // Instead of using the Section we'll just use the shortcut.