[llvm] r224389 - Linker: Drop superseded subprograms
David Blaikie
dblaikie at gmail.com
Thu Dec 18 09:43:05 PST 2014
On Tue, Dec 16, 2014 at 3:23 PM, Duncan P. N. Exon Smith <
dexonsmith at apple.com> wrote:
>
> Author: dexonsmith
> Date: Tue Dec 16 17:23:41 2014
> New Revision: 224389
>
> URL: http://llvm.org/viewvc/llvm-project?rev=224389&view=rev
> Log:
> Linker: Drop superseded subprograms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 When a function gets replaced by `ModuleLinker`, drop superseded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
LTO bootstraps, specifically, yes? (not just a normal bootstrap)
> that are currently asserting out in
> `LexicalScopes::initialize()` due to the explicit instantiations in
> `lib/IR/Dominators.cpp` eventually getting replaced by -argpromotion.
>
> Added:
>
> llvm/trunk/test/Linker/Inputs/replaced-function-matches-first-subprogram.ll
> llvm/trunk/test/Linker/replaced-function-matches-first-subprogram.ll
> Modified:
> llvm/trunk/lib/Linker/LinkModules.cpp
>
> Modified: llvm/trunk/lib/Linker/LinkModules.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Linker/LinkModules.cpp?rev=224389&r1=224388&r2=224389&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Linker/LinkModules.cpp (original)
> +++ llvm/trunk/lib/Linker/LinkModules.cpp Tue Dec 16 17:23:41 2014
> @@ -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<GlobalValue *> LazilyLinkGlobalValues;
>
> + /// Functions that have replaced other functions.
> + SmallPtrSet<const Function *, 16> 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(
> }
>
> NewGV = copyGlobalValueProto(TypeMap, *DstM, SGV);
> +
> + if (DGV && isa<Function>(DGV))
> + if (auto *NewF = dyn_cast<Function>(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<DISubprogram> SPs(CU.getSubprograms());
> + assert(SPs && "Expected valid subprogram array");
> +
> + SmallVector<Metadata *, 16> 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.
>
> Added:
> llvm/trunk/test/Linker/Inputs/replaced-function-matches-first-subprogram.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Linker/Inputs/replaced-function-matches-first-subprogram.ll?rev=224389&view=auto
>
> ==============================================================================
> ---
> llvm/trunk/test/Linker/Inputs/replaced-function-matches-first-subprogram.ll
> (added)
> +++
> llvm/trunk/test/Linker/Inputs/replaced-function-matches-first-subprogram.ll
> Tue Dec 16 17:23:41 2014
> @@ -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}
>
> Added: llvm/trunk/test/Linker/replaced-function-matches-first-subprogram.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Linker/replaced-function-matches-first-subprogram.ll?rev=224389&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/Linker/replaced-function-matches-first-subprogram.ll
> (added)
> +++ llvm/trunk/test/Linker/replaced-function-matches-first-subprogram.ll
> Tue Dec 16 17:23:41 2014
> @@ -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 <class T> struct Class {
> +; int foo() { return 0; }
> +; };
> +; // repro/d1/t1.cpp
> +; #include "t.h"
> +; int foo() { return Class<int>().foo(); }
> +; // repro/d2/t2.cpp
> +; #include "t.h"
> +; template struct Class<int>;
> +
> +%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}
>
>
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