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c89369a941
Instead of dropping subprograms that have been overridden, just set
their function pointers to `nullptr`. This is a minor adjustment to the
stop-gap fix for PR21910 committed in r224487, and fixes the crasher
from PR22792.
The problem that r224487 put a band-aid on: how do we find the canonical
subprogram for a `Function`? Since the backend currently relies on
`DebugInfoFinder` (which does a naive in-order traversal of compile
units and picks the first subprogram) for this, r224487 tried dropping
non-canonical subprograms.
Dropping subprograms fails because the backend *also* builds up a map
from subprogram to compile unit (`DwarfDebug::SPMap`) based on the
subprogram lists. A missing subprogram causes segfaults later when an
inlined reference (such as in this testcase) is created.
Instead, just drop the `Function` pointer to `nullptr`, which nicely
mirrors what happens when an already-inlined `Function` is optimized
out. We can't really be sure that it's the same definition anyway, as
the testcase demonstrates.
This still isn't completely satisfactory. Two flaws at least that I can
think of:
- I still haven't found a straightforward way to make this symmetric
in the IR. (Interestingly, the DWARF output is already symmetric,
and I've tested for that to be sure we don't regress.)
- Using `DebugInfoFinder` to find the canonical subprogram for a
function is kind of crazy. We should just attach metadata to the
function, like this:
define weak i32 @foo(i32, i32) !dbg !MDSubprogram(...) {
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233164 91177308-0d34-0410-b5e6-96231b3b80d8
80 lines
3.8 KiB
LLVM
80 lines
3.8 KiB
LLVM
; RUN: llvm-link %s %S/Inputs/replaced-function-matches-first-subprogram.ll -S | FileCheck %s
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; Generated from C++ source:
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;
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; // repro/t.h
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; template <class T> struct Class {
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; int foo() { return 0; }
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; };
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; // repro/d1/t1.cpp
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; #include "t.h"
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; int foo() { return Class<int>().foo(); }
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; // repro/d2/t2.cpp
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; #include "t.h"
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; template struct Class<int>;
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%struct.Class = type { i8 }
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define i32 @_Z3foov() {
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entry:
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%tmp = alloca %struct.Class, align 1
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%call = call i32 @_ZN5ClassIiE3fooEv(%struct.Class* %tmp), !dbg !14
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ret i32 %call, !dbg !14
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}
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; CHECK: define weak_odr i32 @_ZN5ClassIiE3fooEv(%struct.Class* %this){{.*}}{
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; CHECK-NOT: }
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; CHECK: !dbg ![[LOC:[0-9]+]]
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define linkonce_odr i32 @_ZN5ClassIiE3fooEv(%struct.Class* %this) align 2 {
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entry:
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%this.addr = alloca %struct.Class*, align 8
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store %struct.Class* %this, %struct.Class** %this.addr, align 8
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%this1 = load %struct.Class*, %struct.Class** %this.addr
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ret i32 0, !dbg !15
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}
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; CHECK: !llvm.dbg.cu = !{![[CU1:[0-9]+]], ![[CU2:[0-9]+]]}
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!10, !11, !12}
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!llvm.ident = !{!13}
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; Extract out the list of subprograms from each compile unit.
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; CHECK-DAG: ![[CU1]] = !MDCompileUnit({{.*}} subprograms: ![[SPs1:[0-9]+]]
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; CHECK-DAG: ![[CU2]] = !MDCompileUnit({{.*}} subprograms: ![[SPs2:[0-9]+]]
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!0 = !MDCompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.6.0 (trunk 224193) (llvm/trunk 224197)", isOptimized: false, emissionKind: 2, file: !1, enums: !2, retainedTypes: !2, subprograms: !3, globals: !2, imports: !2)
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!1 = !MDFile(filename: "t1.cpp", directory: "/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d1")
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!2 = !{}
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; Extract out each compile unit's single subprogram. The replaced subprogram's
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; function should drop to null in the first compile unit.
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; CHECK-DAG: ![[SPs1]] = !{![[SP1:[0-9]+]], ![[SP2r:[0-9]+]]}
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; CHECK-DAG: ![[SPs2]] = !{![[SP2:[0-9]+]]}
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!3 = !{!4, !7}
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!4 = !MDSubprogram(name: "foo", line: 2, isLocal: false, isDefinition: true, flags: DIFlagPrototyped, isOptimized: false, scopeLine: 2, file: !1, scope: !5, type: !6, function: i32 ()* @_Z3foov, variables: !2)
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!5 = !MDFile(filename: "t1.cpp", directory: "/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d1")
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!6 = !MDSubroutineType(types: !2)
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; Extract out the file from the replaced subprogram. Confirm that each
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; subprogram is pointing at the correct function.
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; CHECK-DAG: ![[SP1]] = !MDSubprogram({{.*}} function: i32 ()* @_Z3foov
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; CHECK-DAG: ![[SP2]] = !MDSubprogram({{.*}} file: ![[FILE:[0-9]+]],{{.*}} function: i32 (%struct.Class*)* @_ZN5ClassIiE3fooEv
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; We can't use CHECK-NOT/CHECK-SAME with a CHECK-DAG, so rely on field order to
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; prove that there's no function: here.
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; CHECK-DAG: ![[SP2r]] = {{.*}}!MDSubprogram({{.*}} isOptimized: false, variables:
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!7 = !MDSubprogram(name: "foo", line: 2, isLocal: false, isDefinition: true, flags: DIFlagPrototyped, isOptimized: false, scopeLine: 2, file: !8, scope: !9, type: !6, function: i32 (%struct.Class*)* @_ZN5ClassIiE3fooEv, variables: !2)
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; The new subprogram should be pointing at the new directory.
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; CHECK-DAG: ![[FILE]] = !MDFile(filename: "../t.h", directory: "/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d2")
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!8 = !MDFile(filename: "../t.h", directory: "/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d1")
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!9 = !MDFile(filename: "../t.h", directory: "/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d1")
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!10 = !{i32 2, !"Dwarf Version", i32 2}
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!11 = !{i32 2, !"Debug Info Version", i32 3}
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!12 = !{i32 1, !"PIC Level", i32 2}
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!13 = !{!"clang version 3.6.0 (trunk 224193) (llvm/trunk 224197)"}
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!14 = !MDLocation(line: 2, column: 20, scope: !4)
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; The same subprogram should be pointed to by inside the !dbg reference.
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; CHECK: ![[LOC]] = !MDLocation(line: 2, column: 15, scope: ![[SP2]])
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!15 = !MDLocation(line: 2, column: 15, scope: !7)
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