[ThinLTO] Don't convert functions to declarations if force-import-all is enabled

llvm/lib/LTO/LTO.cpp

@@ -75,6 +75,8 @@ static cl::opt<bool>
 
 extern cl::opt<bool> CodeGenDataThinLTOTwoRounds;
 
+extern cl::opt<bool> ForceImportAll;
+
 namespace llvm {
 /// Enable global value internalization in LTO.
 cl::opt<bool> EnableLTOInternalization(
@@ -406,8 +408,11 @@ static void thinLTOResolvePrevailingGUID(
         Visibility = S->getVisibility();
     }
     // Alias and aliasee can't be turned into available_externally.
+    // When force-import-all is used, it indicates that object linking is not
+    // supported by the target. In this case, we can't change the linkage as
+    // well in case the global is converted to declaration.
     else if (!isa<AliasSummary>(S.get()) &&
-             !GlobalInvolvedWithAlias.count(S.get()))
+             !GlobalInvolvedWithAlias.count(S.get()) && !ForceImportAll)
       S->setLinkage(GlobalValue::AvailableExternallyLinkage);
 
     // For ELF, set visibility to the computed visibility from summaries. We

llvm/lib/Transforms/IPO/FunctionImport.cpp

@@ -71,6 +71,10 @@ STATISTIC(NumImportedModules, "Number of modules imported from");
 STATISTIC(NumDeadSymbols, "Number of dead stripped symbols in index");
 STATISTIC(NumLiveSymbols, "Number of live symbols in index");
 
+cl::opt<bool>
+    ForceImportAll("force-import-all", cl::init(false), cl::Hidden,
+                   cl::desc("Import functions with noinline attribute"));
+
 /// Limit on instruction count of imported functions.
 static cl::opt<unsigned> ImportInstrLimit(
     "import-instr-limit", cl::init(100), cl::Hidden, cl::value_desc("N"),
@@ -80,10 +84,6 @@ static cl::opt<int> ImportCutoff(
     "import-cutoff", cl::init(-1), cl::Hidden, cl::value_desc("N"),
     cl::desc("Only import first N functions if N>=0 (default -1)"));
 
-static cl::opt<bool>
-    ForceImportAll("force-import-all", cl::init(false), cl::Hidden,
-                   cl::desc("Import functions with noinline attribute"));
-
 static cl::opt<float>
     ImportInstrFactor("import-instr-evolution-factor", cl::init(0.7),
                       cl::Hidden, cl::value_desc("x"),

llvm/test/ThinLTO/AMDGPU/Inputs/in-f1.ll

@@ -0,0 +1,13 @@
+define void @f1(ptr %v) #0 {
+entry:
+  call void @weak_common(ptr %v)
+  ret void
+}
+
+define weak hidden void @weak_common(ptr %v) #0 {
+entry:
+  store i32 12345, ptr %v
+  ret void
+}
+
+attributes #0 = { noinline }

llvm/test/ThinLTO/AMDGPU/force-import-all.ll

@@ -0,0 +1,27 @@
+; RUN: opt -mtriple=amdgcn-amd-amdhsa -module-summary %s -o %t.main.bc
+; RUN: opt -mtriple=amdgcn-amd-amdhsa -module-summary %p/Inputs/in-f1.ll -o %t.in.bc
+; RUN: llvm-lto -thinlto-action=run -force-import-all %t.main.bc %t.in.bc --thinlto-save-temps=%t.2.
+; RUN: llvm-dis %t.2.0.3.imported.bc -o - | FileCheck --check-prefix=MOD1 %s
+; RUN: llvm-dis %t.2.1.3.imported.bc -o - | FileCheck --check-prefix=MOD2 %s
+
+define void @f0(ptr %p) #0 {
+entry:
+  call void @f1(ptr %p)
+  ret void
+}
+
+define weak hidden void @weak_common(ptr %v) #0 {
+entry:
+  store i32 12345, ptr %v
+  ret void
+}
+
+declare void @f1(ptr)
+
+attributes #0 = { noinline }
+
+; MOD1: define weak hidden void @weak_common
+; MOD1: define available_externally void @f1
+
+; MOD2: define void @f1
+; MOD2: define weak hidden void @weak_common

llvm/test/ThinLTO/AMDGPU/lit.local.cfg

@@ -0,0 +1,2 @@
+if not "AMDGPU" in config.root.targets:
+    config.unsupported = True