[PATCH] D59898: [LCG] Add aliased functions as LCG roots

[Guozhi Wei via Phabricator via llvm-commits]

Carrot created this revision.
Carrot added reviewers: chandlerc, tejohnson.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Current LCG doesn't check aliased functions. So if an internal function has a public alias it will not be added to CG SCC, but it is still reachable from outside through the alias.
So this patch adds aliased functions to SCC.


Repository:
  rL LLVM

https://reviews.llvm.org/D59898

Files:
  lib/Analysis/LazyCallGraph.cpp
  test/Analysis/LazyCallGraph/alias.ll


Index: test/Analysis/LazyCallGraph/alias.ll
===================================================================
--- test/Analysis/LazyCallGraph/alias.ll
+++ test/Analysis/LazyCallGraph/alias.ll
@@ -0,0 +1,29 @@
+; RUN: opt -disable-output -passes=print-lcg %s 2>&1 | FileCheck %s
+;
+; Aliased function should be reachable in CGSCC.
+
+target triple = "x86_64-grtev4-linux-gnu"
+
+; CHECK:        RefSCC with 1 call SCCs:
+; CHECK-NEXT:     SCC with 1 functions:
+; CHECK-NEXT:       bar
+
+; CHECK:       RefSCC with 1 call SCCs:
+; CHECK-NEXT:    SCC with 1 functions:
+; CHECK-NEXT:      foo
+
+
+ at alias1 = weak dso_local alias i8* (i8*), i8* (i8*)* @foo
+
+; Function Attrs: nounwind uwtable
+define dso_local i8* @foo(i8* %returned) {
+  ret i8* %returned
+}
+
+ at alias2 = weak dso_local alias i8* (i8*), i8* (i8*)* @bar
+
+; Function Attrs: nounwind uwtable
+define internal i8* @bar(i8* %returned) {
+  ret i8* %returned
+}
+
Index: lib/Analysis/LazyCallGraph.cpp
===================================================================
--- lib/Analysis/LazyCallGraph.cpp
+++ lib/Analysis/LazyCallGraph.cpp
@@ -187,6 +187,15 @@
     addEdge(EntryEdges.Edges, EntryEdges.EdgeIndexMap, get(F),
             LazyCallGraph::Edge::Ref);
   });
+
+  // Functions has alias are also reachable.
+  for (auto &A : M.aliases()) {
+    if (Function* F = dyn_cast<Function>(A.getAliasee())) {
+      LLVM_DEBUG(dbgs() << "  Adding '" << F->getName()
+                        << "' to entry set of the graph.\n");
+      addEdge(EntryEdges.Edges, EntryEdges.EdgeIndexMap, get(*F), Edge::Ref);
+    }
+  }
 }
 
 LazyCallGraph::LazyCallGraph(LazyCallGraph &&G)


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