[PATCH] D25384: [ThinLTO] Record references to aliases to calls

[Teresa Johnson via llvm-commits]

tejohnson created this revision.
tejohnson added reviewers: davide, mehdi_amini.
tejohnson added a subscriber: llvm-commits.

When there is a call to an alias in the same module, we were not
adding either a reference or call edge. So we could incorrectly think
that the alias was dead if it was inlined in that function, despite
having a reference imported elsewhere. This resulted in unsats at
link time.

Add a reference edge when the call is to an alias, since we won't
add a call edge for it.


https://reviews.llvm.org/D25384

Files:
  lib/Analysis/ModuleSummaryAnalysis.cpp
  test/Bitcode/thinlto-alias2.ll


Index: test/Bitcode/thinlto-alias2.ll
===================================================================
--- /dev/null
+++ test/Bitcode/thinlto-alias2.ll
@@ -0,0 +1,28 @@
+; Test to check the callgraph for call to alias in module.
+; RUN: opt -module-summary %s -o %t.o
+; RUN: llvm-bcanalyzer -dump %t.o | FileCheck %s
+
+; CHECK:       <GLOBALVAL_SUMMARY_BLOCK
+; CHECK-NEXT:    <VERSION
+; CHECK-NEXT:    <PERMODULE {{.*}} op3=1 op4=[[ALIASID:[0-9]+]]/>
+; CHECK-NEXT:    <PERMODULE {{.*}} op0=[[ALIASEEID:[0-9]+]]
+; CHECK-NEXT:    <ALIAS {{.*}} op0=[[ALIASID]] {{.*}} op2=[[ALIASEEID]]/>
+; CHECK-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
+
+; ModuleID = 'thinlto-alias2.ll'
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i32 @main() {
+entry:
+    call void (...) @analias()
+    ret i32 0
+}
+
+ at analias = alias void (...), bitcast (void ()* @aliasee to void (...)*)
+
+define void @aliasee() #0 {
+entry:
+    ret void
+}
+
Index: lib/Analysis/ModuleSummaryAnalysis.cpp
===================================================================
--- lib/Analysis/ModuleSummaryAnalysis.cpp
+++ lib/Analysis/ModuleSummaryAnalysis.cpp
@@ -55,7 +55,7 @@
         // We have a reference to a global value. This should be added to
         // the reference set unless it is a callee. Callees are handled
         // specially by WriteFunction and are added to a separate list.
-        if (!(CS && CS.isCallee(&OI)))
+        if (!(CS && CS.isCallee(&OI) && CS.getCalledFunction()))
           RefEdges.insert(Operand);
         continue;
       }


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