[ThinLTO] Use per-summary flag to prevent exporting locals used in inline asm

Summary:
Instead of using the workaround of suppressing the entire index for
modules that call inline asm that may reference locals, use the
NoRename flag on the summary for any locals in the llvm.used set, and
add a reference edge from any functions containing inline asm.

This avoids issues from having no summaries despite the module defining
global values, which was preventing more aggressive index-based
optimization. It will be followed by a subsequent patch to make a
similar fix for local references in module level asm (to fix PR30610).

Reviewers: mehdi_amini

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D26121

llvm-svn: 285513

2 files changed, 4 insertions, 5 deletions

diff --git a/llvm/include/llvm/Analysis/ModuleSummaryAnalysis.h b/llvm/include/llvm/Analysis/ModuleSummaryAnalysis.h
index c8adc3bf81a..617c3d8f17a 100644
--- a/llvm/include/llvm/Analysis/ModuleSummaryAnalysis.h
+++ b/llvm/include/llvm/Analysis/ModuleSummaryAnalysis.h
@@ -70,11 +70,6 @@ public:
 // object for the module, to be written to bitcode or LLVM assembly.
 //
 ModulePass *createModuleSummaryIndexWrapperPass();
-
-/// Returns true if \p M is eligible for ThinLTO promotion.
-///
-/// Currently we check if it has any any InlineASM that uses an internal symbol.
-bool moduleCanBeRenamedForThinLTO(const Module &M);
 }
 
 #endif
diff --git a/llvm/include/llvm/IR/ModuleSummaryIndex.h b/llvm/include/llvm/IR/ModuleSummaryIndex.h
index 1ceb9eb32cb..b3775904e75 100644
--- a/llvm/include/llvm/IR/ModuleSummaryIndex.h
+++ b/llvm/include/llvm/IR/ModuleSummaryIndex.h
@@ -194,6 +194,10 @@ public:
   /// possibly referenced from inline assembly, etc).
   bool noRename() const { return Flags.NoRename; }
 
+  /// Flag that this global value cannot be renamed (in a specific section,
+  /// possibly referenced from inline assembly, etc).
+  void setNoRename() { Flags.NoRename = true; }
+
   /// Record a reference from this global value to the global value identified
   /// by \p RefGUID.
   void addRefEdge(GlobalValue::GUID RefGUID) { RefEdgeList.push_back(RefGUID); }