From 875902689353d92ee3ff49fccb3412b2656176c7 Mon Sep 17 00:00:00 2001 From: "Duncan P. N. Exon Smith" Date: Tue, 16 Dec 2014 23:23:41 +0000 Subject: [PATCH] Linker: Drop superseded subprograms When a function gets replaced by `ModuleLinker`, drop superseded subprograms. This ensures that the "first" subprogram pointing at a function is the same one that `!dbg` references point at. This is a stop-gap fix for PR21910. Notably, this fixes Release+Asserts bootstraps that are currently asserting out in `LexicalScopes::initialize()` due to the explicit instantiations in `lib/IR/Dominators.cpp` eventually getting replaced by -argpromotion. llvm-svn: 224389 --- llvm/lib/Linker/LinkModules.cpp | 54 ++++++++++++++++ .../replaced-function-matches-first-subprogram.ll | 27 ++++++++ .../replaced-function-matches-first-subprogram.ll | 75 ++++++++++++++++++++++ 3 files changed, 156 insertions(+) create mode 100644 llvm/test/Linker/Inputs/replaced-function-matches-first-subprogram.ll create mode 100644 llvm/test/Linker/replaced-function-matches-first-subprogram.ll diff --git a/llvm/lib/Linker/LinkModules.cpp b/llvm/lib/Linker/LinkModules.cpp index 0e14415..7f3e5b3 100644 --- a/llvm/lib/Linker/LinkModules.cpp +++ b/llvm/lib/Linker/LinkModules.cpp @@ -19,6 +19,7 @@ #include "llvm/ADT/SmallString.h" #include "llvm/ADT/Statistic.h" #include "llvm/IR/Constants.h" +#include "llvm/IR/DebugInfo.h" #include "llvm/IR/DiagnosticInfo.h" #include "llvm/IR/DiagnosticPrinter.h" #include "llvm/IR/LLVMContext.h" @@ -416,6 +417,9 @@ class ModuleLinker { // Vector of GlobalValues to lazily link in. std::vector LazilyLinkGlobalValues; + /// Functions that have replaced other functions. + SmallPtrSet OverridingFunctions; + Linker::DiagnosticHandlerFunction DiagnosticHandler; public: @@ -494,6 +498,7 @@ private: bool linkGlobalValueBody(GlobalValue &Src); void linkNamedMDNodes(); + void stripReplacedSubprograms(); }; } @@ -1078,6 +1083,10 @@ bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) { } NewGV = copyGlobalValueProto(TypeMap, *DstM, SGV); + + if (DGV && isa(DGV)) + if (auto *NewF = dyn_cast(NewGV)) + OverridingFunctions.insert(NewF); } NewGV->setUnnamedAddr(HasUnnamedAddr); @@ -1244,6 +1253,48 @@ void ModuleLinker::linkNamedMDNodes() { } } +/// Drop DISubprograms that have been superseded. +/// +/// FIXME: this creates an asymmetric result: we strip losing subprograms from +/// DstM, but leave losing subprograms in SrcM. Instead we should also strip +/// losers from SrcM, but this requires extra plumbing in MapValue. +void ModuleLinker::stripReplacedSubprograms() { + // Avoid quadratic runtime by returning early when there's nothing to do. + if (OverridingFunctions.empty()) + return; + + // Move the functions now, so the set gets cleared even on early returns. + auto Functions = std::move(OverridingFunctions); + OverridingFunctions.clear(); + + // Drop subprograms whose functions have been overridden by the new compile + // unit. + NamedMDNode *CompileUnits = DstM->getNamedMetadata("llvm.dbg.cu"); + if (!CompileUnits) + return; + for (unsigned I = 0, E = CompileUnits->getNumOperands(); I != E; ++I) { + DICompileUnit CU(CompileUnits->getOperand(I)); + assert(CU && "Expected valid compile unit"); + + DITypedArray SPs(CU.getSubprograms()); + assert(SPs && "Expected valid subprogram array"); + + SmallVector NewSPs; + NewSPs.reserve(SPs.getNumElements()); + for (unsigned S = 0, SE = SPs.getNumElements(); S != SE; ++S) { + DISubprogram SP = SPs.getElement(S); + if (SP && SP.getFunction() && Functions.count(SP.getFunction())) + continue; + + NewSPs.push_back(SP); + } + + // Redirect operand to the overriding subprogram. + if (NewSPs.size() != SPs.getNumElements()) + CU.replaceSubprograms(DIArray(MDNode::get(DstM->getContext(), NewSPs))); + } +} + /// Merge the linker flags in Src into the Dest module. bool ModuleLinker::linkModuleFlagsMetadata() { // If the source module has no module flags, we are done. @@ -1509,6 +1560,9 @@ bool ModuleLinker::run() { linkGlobalValueBody(Src); } + // Strip replaced subprograms before linking together compile units. + stripReplacedSubprograms(); + // Remap all of the named MDNodes in Src into the DstM module. We do this // after linking GlobalValues so that MDNodes that reference GlobalValues // are properly remapped. diff --git a/llvm/test/Linker/Inputs/replaced-function-matches-first-subprogram.ll b/llvm/test/Linker/Inputs/replaced-function-matches-first-subprogram.ll new file mode 100644 index 0000000..fb7b634 --- /dev/null +++ b/llvm/test/Linker/Inputs/replaced-function-matches-first-subprogram.ll @@ -0,0 +1,27 @@ +%struct.Class = type { i8 } + +define weak_odr i32 @_ZN5ClassIiE3fooEv(%struct.Class* %this) align 2 { +entry: + %this.addr = alloca %struct.Class*, align 8 + store %struct.Class* %this, %struct.Class** %this.addr, align 8 + %this1 = load %struct.Class** %this.addr + ret i32 0, !dbg !12 +} + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!8, !9, !10} +!llvm.ident = !{!11} + +!0 = !{!"0x11\004\00clang version 3.6.0 (trunk 224193) (llvm/trunk 224197)\000\00\000\00\002", !1, !2, !2, !3, !2, !2} ; [ DW_TAG_compile_unit ] [/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d2/t2.cpp] [DW_LANG_C_plus_plus] +!1 = !{!"t2.cpp", !"/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d2"} +!2 = !{} +!3 = !{!4} +!4 = !{!"0x2e\00foo\00foo\00\002\000\001\000\000\00256\000\002", !5, !6, !7, null, i32 (%struct.Class*)* @_ZN5ClassIiE3fooEv, null, null, !2} ; [ DW_TAG_subprogram ] [line 2] [def] [foo] +!5 = !{!"../t.h", !"/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d2"} +!6 = !{!"0x29", !5} ; [ DW_TAG_file_type ] [/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d2/../t.h] +!7 = !{!"0x15\00\000\000\000\000\000\000", null, null, null, !2, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ] +!8 = !{i32 2, !"Dwarf Version", i32 2} +!9 = !{i32 2, !"Debug Info Version", i32 2} +!10 = !{i32 1, !"PIC Level", i32 2} +!11 = !{!"clang version 3.6.0 (trunk 224193) (llvm/trunk 224197)"} +!12 = !{i32 2, i32 15, !4, null} diff --git a/llvm/test/Linker/replaced-function-matches-first-subprogram.ll b/llvm/test/Linker/replaced-function-matches-first-subprogram.ll new file mode 100644 index 0000000..6511384 --- /dev/null +++ b/llvm/test/Linker/replaced-function-matches-first-subprogram.ll @@ -0,0 +1,75 @@ +; RUN: llvm-link %s %S/Inputs/replaced-function-matches-first-subprogram.ll -S | FileCheck %s + +; Generated from C++ source: +; +; // repro/t.h +; template struct Class { +; int foo() { return 0; } +; }; +; // repro/d1/t1.cpp +; #include "t.h" +; int foo() { return Class().foo(); } +; // repro/d2/t2.cpp +; #include "t.h" +; template struct Class; + +%struct.Class = type { i8 } + +define i32 @_Z3foov() { +entry: + %tmp = alloca %struct.Class, align 1 + %call = call i32 @_ZN5ClassIiE3fooEv(%struct.Class* %tmp), !dbg !14 + ret i32 %call, !dbg !14 +} + +; CHECK: define weak_odr i32 @_ZN5ClassIiE3fooEv(%struct.Class* %this){{.*}}{ +; CHECK-NOT: } +; CHECK: !dbg ![[LOC:[0-9]+]] +define linkonce_odr i32 @_ZN5ClassIiE3fooEv(%struct.Class* %this) align 2 { +entry: + %this.addr = alloca %struct.Class*, align 8 + store %struct.Class* %this, %struct.Class** %this.addr, align 8 + %this1 = load %struct.Class** %this.addr + ret i32 0, !dbg !15 +} + +; CHECK: !llvm.dbg.cu = !{![[CU1:[0-9]+]], ![[CU2:[0-9]+]]} +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!10, !11, !12} +!llvm.ident = !{!13} + +; Extract out the list of subprograms from each compile unit. +; CHECK-DAG: ![[CU1]] = !{!"0x11{{[^"]+}}", {{[^,]+}}, {{[^,]+}}, {{[^,]+}}, ![[SPs1:[0-9]+]], +; CHECK-DAG: ![[CU2]] = !{!"0x11{{[^"]+}}", {{[^,]+}}, {{[^,]+}}, {{[^,]+}}, ![[SPs2:[0-9]+]], +!0 = !{!"0x11\004\00clang version 3.6.0 (trunk 224193) (llvm/trunk 224197)\000\00\000\00\002", !1, !2, !2, !3, !2, !2} ; [ DW_TAG_compile_unit ] [/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d1/t1.cpp] [DW_LANG_C_plus_plus] +!1 = !{!"t1.cpp", !"/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d1"} +!2 = !{} + +; Extract out each compile unit's single subprogram. The replaced subprogram +; should be dropped by the first compile unit. +; CHECK-DAG: ![[SPs1]] = !{![[SP1:[0-9]+]]} +; CHECK-DAG: ![[SPs2]] = !{![[SP2:[0-9]+]]} +!3 = !{!4, !7} +!4 = !{!"0x2e\00foo\00foo\00\002\000\001\000\000\00256\000\002", !1, !5, !6, null, i32 ()* @_Z3foov, null, null, !2} ; [ DW_TAG_subprogram ] [line 2] [def] [foo] +!5 = !{!"0x29", !1} ; [ DW_TAG_file_type ] [/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d1/t1.cpp] +!6 = !{!"0x15\00\000\000\000\000\000\000", null, null, null, !2, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ] + +; Extract out the file from the replaced subprogram. Confirm that each +; subprogram is pointing at the correct function. +; CHECK-DAG: ![[SP1]] = !{!"0x2e{{[^"]+}}", {{.*}}, i32 ()* @_Z3foov, +; CHECK-DAG: ![[SP2]] = !{!"0x2e{{[^"]+}}", ![[FILE:[0-9]+]], {{.*}}, i32 (%struct.Class*)* @_ZN5ClassIiE3fooEv, +!7 = !{!"0x2e\00foo\00foo\00\002\000\001\000\000\00256\000\002", !8, !9, !6, null, i32 (%struct.Class*)* @_ZN5ClassIiE3fooEv, null, null, !2} ; [ DW_TAG_subprogram ] [line 2] [def] [foo] + +; The new subprogram should be pointing at the new directory. +; CHECK-DAG: ![[FILE]] = !{!"../t.h", !"/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d2"} +!8 = !{!"../t.h", !"/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d1"} +!9 = !{!"0x29", !8} ; [ DW_TAG_file_type ] [/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d1/../t.h] +!10 = !{i32 2, !"Dwarf Version", i32 2} +!11 = !{i32 2, !"Debug Info Version", i32 2} +!12 = !{i32 1, !"PIC Level", i32 2} +!13 = !{!"clang version 3.6.0 (trunk 224193) (llvm/trunk 224197)"} +!14 = !{i32 2, i32 20, !4, null} + +; The same subprogram should be pointed to by inside the !dbg reference. +; CHECK: ![[LOC]] = !{i32 2, i32 15, ![[SP2]], null} +!15 = !{i32 2, i32 15, !7, null} -- 2.7.4