Restore "[ThinLTO] Prevent exporting of locals used/defined in module level asm"

This restores the rest of r286297 (part was restored in r286475).
Specifically, it restores the part requiring adding a dependency from
the Analysis to Object library (downstream use changed to correctly
model split BitReader vs BitWriter libraries).

Original description of this part of patch follows:

Module level asm may also contain defs of values. We need to prevent
export of any refs to local values defined in module level asm (e.g. a
ref in normal IR), since that also requires renaming/promotion of the
local. To do that, the summary index builder looks at all values in the
module level asm string that are not marked Weak or Global, which is
exactly the set of locals that are defined. A summary is created for
each of these local defs and flagged as NoRename.

This required adding handling to the BitcodeWriter to look at GV
declarations to see if they have a summary (rather than skipping them
all).

Finally, added an assert to IRObjectFile::CollectAsmUndefinedRefs to
ensure that an MCAsmParser is available, otherwise the module asm parse
would silently fail. Initialized the asm parser in the opt tool for use
in testing this fix.

Fixes PR30610.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286844 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 3 insertions, 0 deletions

diff --git a/include/llvm/Support/TargetRegistry.h b/include/llvm/Support/TargetRegistry.h
index f868c07df182..954cdb13abaf 100644
--- a/include/llvm/Support/TargetRegistry.h
+++ b/include/llvm/Support/TargetRegistry.h
@@ -280,6 +280,9 @@ public:
   /// hasMCAsmBackend - Check if this target supports .o generation.
   bool hasMCAsmBackend() const { return MCAsmBackendCtorFn != nullptr; }
 
+  /// hasMCAsmParser - Check if this target supports assembly parsing.
+  bool hasMCAsmParser() const { return MCAsmParserCtorFn != nullptr; }
+
   /// @}
   /// @name Feature Constructors
   /// @{