llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-llvm-transforms Author: Paul Kirth (ilovepi) <details> <summary>Changes</summary> Since ThinLTOBitcodeWriterPass handles many things for CFI and WPD, like updating vtable linkage, we need to prevent those changes from persisting in the non-LTO object code we will compile under FatLTO. The only non-invasive way to do that is to clone the module when serializing the module in ThinLTOBitcodeWriterPass. We may be able to avoid cloning in the future with additional infrastructure to restore the IR to its original state. Fixes #<!-- -->139440 --- Full diff: https://github.com/llvm/llvm-project/pull/139999.diff 2 Files Affected: - (modified) llvm/lib/Transforms/IPO/EmbedBitcodePass.cpp (+5-1) - (modified) llvm/test/Transforms/EmbedBitcode/embed-wpd.ll (+4-3) ``````````diff diff --git a/llvm/lib/Transforms/IPO/EmbedBitcodePass.cpp b/llvm/lib/Transforms/IPO/EmbedBitcodePass.cpp index 73f567734a91b..7a378c61cb899 100644 --- a/llvm/lib/Transforms/IPO/EmbedBitcodePass.cpp +++ b/llvm/lib/Transforms/IPO/EmbedBitcodePass.cpp @@ -16,6 +16,7 @@ #include "llvm/Support/raw_ostream.h" #include "llvm/TargetParser/Triple.h" #include "llvm/Transforms/IPO/ThinLTOBitcodeWriter.h" +#include "llvm/Transforms/Utils/Cloning.h" #include "llvm/Transforms/Utils/ModuleUtils.h" #include <string> @@ -33,8 +34,11 @@ PreservedAnalyses EmbedBitcodePass::run(Module &M, ModuleAnalysisManager &AM) { std::string Data; raw_string_ostream OS(Data); + // Clone the module with with Thin LTO, since ThinLTOBitcodeWriterPass changes + // vtable linkage that would break the non-lto object code for FatLTO. if (IsThinLTO) - ThinLTOBitcodeWriterPass(OS, /*ThinLinkOS=*/nullptr).run(M, AM); + ThinLTOBitcodeWriterPass(OS, /*ThinLinkOS=*/nullptr) + .run(*llvm::CloneModule(M), AM); else BitcodeWriterPass(OS, /*ShouldPreserveUseListOrder=*/false, EmitLTOSummary) .run(M, AM); diff --git a/llvm/test/Transforms/EmbedBitcode/embed-wpd.ll b/llvm/test/Transforms/EmbedBitcode/embed-wpd.ll index f1f7712f54039..54931be42b4eb 100644 --- a/llvm/test/Transforms/EmbedBitcode/embed-wpd.ll +++ b/llvm/test/Transforms/EmbedBitcode/embed-wpd.ll @@ -1,12 +1,13 @@ ; RUN: opt --mtriple x86_64-unknown-linux-gnu < %s -passes="embed-bitcode<thinlto>" -S | FileCheck %s -; CHECK-NOT: $_ZTV3Foo = comdat any +; CHECK: $_ZTV3Foo = comdat any $_ZTV3Foo = comdat any $_ZTI3Foo = comdat any -; CHECK: @_ZTV3Foo = external hidden unnamed_addr constant { [5 x ptr] }, align 8 -; CHECK: @_ZTI3Foo = linkonce_odr hidden constant { ptr, ptr, ptr } { ptr getelementptr inbounds (ptr, ptr @_ZTVN10__cxxabiv120__si_class_type_infoE, i64 2), ptr @_ZTS3Foo, ptr @_ZTISt13runtime_error }, comdat, align 8 +;; ThinLTOBitcodeWriter will remove the vtable for Foo, and make it an external symbol +; CHECK: @_ZTV3Foo = linkonce_odr hidden unnamed_addr constant { [5 x ptr] } { [5 x ptr] [ptr null, ptr @_ZTI3Foo, ptr @_ZN3FooD2Ev, ptr @_ZN3FooD0Ev, ptr @_ZNKSt13runtime_error4whatEv] }, comdat, align 8, !type !0, !type !1, !type !2, !type !3, !type !4, !type !5 +; CHECK-NOT: @foo = external unnamed_addr constant { [5 x ptr] }, align 8 ; CHECK: @llvm.embedded.object = private constant {{.*}}, section ".llvm.lto", align 1 ; CHECK: @llvm.compiler.used = appending global [1 x ptr] [ptr @llvm.embedded.object], section "llvm.metadata" @_ZTV3Foo = linkonce_odr hidden unnamed_addr constant { [5 x ptr] } { [5 x ptr] [ptr null, ptr @_ZTI3Foo, ptr @_ZN3FooD2Ev, ptr @_ZN3FooD0Ev, ptr @_ZNKSt13runtime_error4whatEv] }, comdat, align 8, !type !0, !type !1, !type !2, !type !3, !type !4, !type !5 `````````` </details> https://github.com/llvm/llvm-project/pull/139999 _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
