Fix a few issues with comdat handling on COFF.

* Section association cannot use just the section name as many
sections can have the same name. With this patch, the comdat symbol in
an assoc section is interpreted to mean a symbol in the associated
section and the mapping is discovered from it.

* Comdat symbols were not being set correctly. Instead we were getting
whatever was output first for that section.

A consequence is that associative sections now must use .section to
set the association. Using .linkonce would not work since it is not
possible to change a sections comdat symbol (it is used to decide if
we should create a new section or reuse an existing one).

This includes r210298, which was reverted because it was asserting
on an associated section having the same comdat as the associated
section.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210367 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 1 insertions, 3 deletions

diff --git a/include/llvm/MC/MCContext.h b/include/llvm/MC/MCContext.h
index 7557e7629b..2f9b32b984 100644
--- a/include/llvm/MC/MCContext.h
+++ b/include/llvm/MC/MCContext.h
@@ -273,9 +273,7 @@ namespace llvm {
     const MCSectionCOFF *getCOFFSection(StringRef Section,
                                         unsigned Characteristics,
                                         SectionKind Kind,
-                                        StringRef COMDATSymName,
-                                        int Selection,
-                                        const MCSectionCOFF *Assoc = nullptr);
+                                        StringRef COMDATSymName, int Selection);
 
     const MCSectionCOFF *getCOFFSection(StringRef Section,
                                         unsigned Characteristics,