[PATCH] D108689: [Linker] Support weak symbols in nodeduplicate COMDAT group

[Petr Hosek via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG92f54e1c7522: [Linker] Support weak symbols in nodeduplicate COMDAT group (authored by phosek).

Changed prior to commit:
  https://reviews.llvm.org/D108689?vs=369141&id=369824#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D108689/new/

https://reviews.llvm.org/D108689

Files:
  llvm/lib/Linker/LinkModules.cpp
  llvm/test/Linker/comdat-nodeduplicate.ll


Index: llvm/test/Linker/comdat-nodeduplicate.ll
===================================================================
--- llvm/test/Linker/comdat-nodeduplicate.ll
+++ llvm/test/Linker/comdat-nodeduplicate.ll
@@ -3,14 +3,16 @@
 
 ; CHECK: error: Linking COMDATs named 'foo': nodeduplicate has been violated!
 
-; RUN: not llvm-link -S %t/2.ll %t/2-aux.ll 2>&1 | FileCheck %s --check-prefix=CHECK2
-; RUN: not llvm-link -S %t/2-aux.ll %t/2.ll 2>&1 | FileCheck %s --check-prefix=CHECK2
+; RUN: llvm-link -S %t/2.ll %t/2-aux.ll | FileCheck %s --check-prefix=CHECK2
+; RUN: llvm-link -S %t/2-aux.ll %t/2.ll | FileCheck %s --check-prefix=CHECK2
 
-; CHECK2: error: Linking COMDATs named 'foo'
+; CHECK2-DAG: @foo = global i64 2, section "data", comdat, align 8
+; CHECK2-DAG: @bar = weak global i64 0, section "cnts", comdat($foo)
+; CHECK2-DAG: @qux = weak_odr global i64 4, comdat($foo)
 
 ; RUN: not llvm-link -S %t/non-var.ll %t/non-var.ll 2>&1 | FileCheck %s --check-prefix=NONVAR
 
-; NONVAR: error: Linking COMDATs named 'foo': nodeduplicate has been violated!
+; NONVAR: error: Linking COMDATs named 'foo': GlobalVariable required for data dependent selection!
 
 ;--- 1.ll
 $foo = comdat nodeduplicate
Index: llvm/lib/Linker/LinkModules.cpp
===================================================================
--- llvm/lib/Linker/LinkModules.cpp
+++ llvm/lib/Linker/LinkModules.cpp
@@ -179,9 +179,25 @@
     // Go with Dst.
     From = LinkFrom::Dst;
     break;
-  case Comdat::SelectionKind::NoDeduplicate:
-    return emitError("Linking COMDATs named '" + ComdatName +
-                     "': nodeduplicate has been violated!");
+  case Comdat::SelectionKind::NoDeduplicate: {
+    const GlobalVariable *DstGV;
+    const GlobalVariable *SrcGV;
+    if (getComdatLeader(DstM, ComdatName, DstGV) ||
+        getComdatLeader(*SrcM, ComdatName, SrcGV))
+      return true;
+
+    if (SrcGV->isWeakForLinker()) {
+      // Go with Dst.
+      From = LinkFrom::Dst;
+    } else if (DstGV->isWeakForLinker()) {
+      // Go with Src.
+      From = LinkFrom::Src;
+    } else {
+      return emitError("Linking COMDATs named '" + ComdatName +
+                       "': nodeduplicate has been violated!");
+    }
+    break;
+  }
   case Comdat::SelectionKind::ExactMatch:
   case Comdat::SelectionKind::Largest:
   case Comdat::SelectionKind::SameSize: {


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