[PATCH] D145859: [Clang][CodeGen] Fix linkage of template parameter objects

[Alexander Shaposhnikov via Phabricator via cfe-commits]

alexander-shaposhnikov created this revision.
alexander-shaposhnikov added reviewers: rsmith, aaron.ballman.
alexander-shaposhnikov created this object with visibility "All Users".
Herald added a project: All.
alexander-shaposhnikov requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

This diff fixes linkage of template parameter objects.
The associated GitHub issue: https://github.com/llvm/llvm-project/issues/51571#

Test plan:
1/ ninja check-all
2/ bootstrapped Clang passes tests


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D145859

Files:
  clang/lib/CodeGen/CodeGenModule.cpp
  clang/test/CodeGenCXX/template-param-objects-linkage.cpp


Index: clang/test/CodeGenCXX/template-param-objects-linkage.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCXX/template-param-objects-linkage.cpp
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -std=c++20 %s -emit-llvm -o - | 
FileCheck %s
+
+struct S { char buf[32]; };
+template<S s> constexpr const char* f() { return s.buf; }
+const char* fbuf = f<S{"a"}>();
+// CHECK: @_ZTAXtl1StlA32_cLc97EEEE = linkonce_odr constant { <{ i8, [31 x i8] 
}> }
+
+namespace {
+  struct UN { char buf[64]; };
+}
+template <UN un> constexpr const char* g() { return un.buf; }
+const char* gbuf = g<UN{"b"}>();
+// CHECK: @_ZTAXtlN12_GLOBAL__N_12UNEtlA64_cLc98EEEE = internal constant { <{ 
i8, [63 x i8] }> }
+
+struct Foo { int *i; };
+int m = 0;
+namespace { int n; }
+
+template <Foo foo>
+const int* h() { return foo.i; }
+
+const int* hm = h<Foo{&m}>();
+// CHECK: @_ZTAXtl3FooadL_Z1mEEE = linkonce_odr constant %struct.Foo { ptr @m }
+
+const int* hn = h<Foo{&n}>();
+// CHECK: @_ZTAXtl3FooadL_ZN12_GLOBAL__N_11nEEEE = internal constant 
%struct.Foo { ptr @_ZN12_GLOBAL__N_11nE }
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -3238,9 +3238,12 @@
     return ConstantAddress::invalid();
   }
 
-  auto *GV = new llvm::GlobalVariable(
-      getModule(), Init->getType(),
-      /*isConstant=*/true, llvm::GlobalValue::LinkOnceODRLinkage, Init, Name);
+  llvm::GlobalValue::LinkageTypes Linkage =
+      isExternallyVisible(TPO->getLinkageAndVisibility().getLinkage())
+          ? llvm::GlobalValue::LinkOnceODRLinkage
+          : llvm::GlobalValue::InternalLinkage;
+  auto *GV = new llvm::GlobalVariable(getModule(), Init->getType(),
+                                      /*isConstant=*/true, Linkage, Init, 
Name);
   if (supportsCOMDAT())
     GV->setComdat(TheModule.getOrInsertComdat(GV->getName()));
   Emitter.finalize(GV);



Index: clang/test/CodeGenCXX/template-param-objects-linkage.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCXX/template-param-objects-linkage.cpp
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -std=c++20 %s -emit-llvm -o - | FileCheck %s
+
+struct S { char buf[32]; };
+template<S s> constexpr const char* f() { return s.buf; }
+const char* fbuf = f<S{"a"}>();
+// CHECK: @_ZTAXtl1StlA32_cLc97EEEE = linkonce_odr constant { <{ i8, [31 x i8] }> }
+
+namespace {
+  struct UN { char buf[64]; };
+}
+template <UN un> constexpr const char* g() { return un.buf; }
+const char* gbuf = g<UN{"b"}>();
+// CHECK: @_ZTAXtlN12_GLOBAL__N_12UNEtlA64_cLc98EEEE = internal constant { <{ i8, [63 x i8] }> }
+
+struct Foo { int *i; };
+int m = 0;
+namespace { int n; }
+
+template <Foo foo>
+const int* h() { return foo.i; }
+
+const int* hm = h<Foo{&m}>();
+// CHECK: @_ZTAXtl3FooadL_Z1mEEE = linkonce_odr constant %struct.Foo { ptr @m }
+
+const int* hn = h<Foo{&n}>();
+// CHECK: @_ZTAXtl3FooadL_ZN12_GLOBAL__N_11nEEEE = internal constant %struct.Foo { ptr @_ZN12_GLOBAL__N_11nE }
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -3238,9 +3238,12 @@
     return ConstantAddress::invalid();
   }
 
-  auto *GV = new llvm::GlobalVariable(
-      getModule(), Init->getType(),
-      /*isConstant=*/true, llvm::GlobalValue::LinkOnceODRLinkage, Init, Name);
+  llvm::GlobalValue::LinkageTypes Linkage =
+      isExternallyVisible(TPO->getLinkageAndVisibility().getLinkage())
+          ? llvm::GlobalValue::LinkOnceODRLinkage
+          : llvm::GlobalValue::InternalLinkage;
+  auto *GV = new llvm::GlobalVariable(getModule(), Init->getType(),
+                                      /*isConstant=*/true, Linkage, Init, Name);
   if (supportsCOMDAT())
     GV->setComdat(TheModule.getOrInsertComdat(GV->getName()));
   Emitter.finalize(GV);

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