[PATCH] D35604: LowerTypeTests: Drop function type metadata only if we're going to replace it.

[Peter Collingbourne via Phabricator via llvm-commits]

pcc updated this revision to Diff 107422.
pcc marked 2 inline comments as done.
pcc added a comment.

- Address review comments


https://reviews.llvm.org/D35604

Files:
  llvm/lib/Transforms/IPO/LowerTypeTests.cpp
  llvm/test/Transforms/LowerTypeTests/export-icall.ll


Index: llvm/test/Transforms/LowerTypeTests/export-icall.ll
===================================================================
--- llvm/test/Transforms/LowerTypeTests/export-icall.ll
+++ llvm/test/Transforms/LowerTypeTests/export-icall.ll
@@ -9,18 +9,26 @@
 }
 
 declare !type !8 void @f(i32 %x)
+define available_externally void @f2(i32 %x) !type !8 {
+  ret void
+}
+define void @f3(i32 %x) !type !8 {
+  ret void
+}
 
-!cfi.functions = !{!0, !1, !3, !4, !5, !6}
+!cfi.functions = !{!0, !1, !3, !9, !10, !4, !5, !6}
 
 ; declaration of @h with a different type is ignored
 !0 = !{!"h", i8 1, !7}
 
 ; extern_weak declaration of @h with a different type is ignored as well
 !1 = !{!"h", i8 2, !8}
 !2 = !{i64 0, !"typeid1"}
 
-; definition of @f replaces types on the IR declaration above
+; definitions of @f and @f2 replace types on the IR declarations above
 !3 = !{!"f", i8 0, !2}
+!9 = !{!"f2", i8 0, !2}
+!10 = !{!"f3", i8 0, !2}
 !4 = !{!"external", i8 1, !2}
 !5 = !{!"external_weak", i8 2, !2}
 !6 = !{!"g", i8 0, !7}
@@ -30,10 +38,11 @@
 
 ; CHECK-DAG: @__typeid_typeid1_global_addr = hidden alias i8, bitcast (void ()* [[JT1:.*]] to i8*)
 ; CHECK-DAG: @__typeid_typeid1_align = hidden alias i8, inttoptr (i8 3 to i8*)
-; CHECK-DAG: @__typeid_typeid1_size_m1 = hidden alias i8, inttoptr (i64 3 to i8*)
+; CHECK-DAG: @__typeid_typeid1_size_m1 = hidden alias i8, inttoptr (i64 4 to i8*)
 
 ; CHECK-DAG: @h                    = alias void (i8), bitcast (void ()* [[JT1]] to void (i8)*)
 ; CHECK-DAG: @f                    = alias void (i32), {{.*}}getelementptr {{.*}}void ()* [[JT1]]
+; CHECK-DAG: @f2                   = alias void (i32), {{.*}}getelementptr {{.*}}void ()* [[JT1]]
 ; CHECK-DAG: @external.cfi_jt      = hidden alias void (), {{.*}}getelementptr {{.*}}void ()* [[JT1]]
 ; CHECK-DAG: @external_weak.cfi_jt = hidden alias void (), {{.*}}getelementptr {{.*}}void ()* [[JT1]]
 
@@ -45,6 +54,9 @@
 ; CHECK-DAG: declare !type !{{.*}} void @external()
 ; CHECK-DAG: declare !type !{{.*}} void @external_weak()
 ; CHECK-DAG: declare !type !{{.*}} void @f.cfi(i32)
+; CHECK-DAG: declare !type !{{.*}} void @f2.cfi(i32)
+; CHECK-DAG: define void @f3(i32 {{.*}}) !type !3
+; CHECK-DAG: !3 = !{i64 0, !"typeid3"}
 ; CHECK-DAG: declare !type !{{.*}} void @g.cfi()
 
 
@@ -62,6 +74,7 @@
 
 ; SUMMARY:      CfiFunctionDefs:
 ; SUMMARY-NEXT:   - f
+; SUMMARY-NEXT:   - f2
 ; SUMMARY-NEXT:   - g
 ; SUMMARY-NEXT:   - h
 ; SUMMARY-NEXT: CfiFunctionDecls:
Index: llvm/lib/Transforms/IPO/LowerTypeTests.cpp
===================================================================
--- llvm/lib/Transforms/IPO/LowerTypeTests.cpp
+++ llvm/lib/Transforms/IPO/LowerTypeTests.cpp
@@ -1512,14 +1512,27 @@
               FunctionType::get(Type::getVoidTy(M.getContext()), false),
               GlobalVariable::ExternalLinkage, FunctionName, &M);
 
-        if (Linkage == CFL_Definition)
-          F->eraseMetadata(LLVMContext::MD_type);
+        // If the function is available_externally, remove its definition so
+        // that it is handled the same way as a declaration. Later we will try
+        // to create an alias using this function's linkage, which will fail if
+        // the linkage is available_externally. This will also result in us
+        // following the code path below to replace the type metadata.
+        if (F->hasAvailableExternallyLinkage()) {
+          F->setLinkage(GlobalValue::ExternalLinkage);
+          F->deleteBody();
+          F->setComdat(nullptr);
+          F->clearMetadata();
+        }
 
+        // If the function in the full LTO module is a declaration, replace its
+        // type metadata with the type metadata we found in cfi.functions. That
+        // metadata is presumed to be more accurate than the metadata attached
+        // to the declaration.
         if (F->isDeclaration()) {
           if (Linkage == CFL_WeakDeclaration)
             F->setLinkage(GlobalValue::ExternalWeakLinkage);
 
-          SmallVector<MDNode *, 2> Types;
+          F->eraseMetadata(LLVMContext::MD_type);
           for (unsigned I = 2; I < FuncMD->getNumOperands(); ++I)
             F->addMetadata(LLVMContext::MD_type,
                            *cast<MDNode>(FuncMD->getOperand(I).get()));


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