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[DwarfDebug] Skip entries to big for 16 bit size field in Dwarf < 5.

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Nothing prevents entries from being bigger than the 16 bit size field in
Dwarf < 5. For entries that are too big, just emit an empty entry
instead of crashing.

This fixes PR41038.

Reviewers: probinson, aprantl, davide

Reviewed By: probinson

Differential Revision: https://reviews.llvm.org/D59518

llvm-svn: 356514
This commit is contained in:
Florian Hahn 2019-03-19 20:37:06 +00:00
parent 282555ad82
commit 1663c9466f
2 changed files with 56 additions and 1 deletions
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8
llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
View File

@ -2037,8 +2037,14 @@ void DwarfDebug::emitDebugLocEntryLocation(const DebugLocStream::Entry &Entry,
Asm->OutStreamer->AddComment("Loc expr size");
if (getDwarfVersion() >= 5)
Asm->EmitULEB128(DebugLocs.getBytes(Entry).size());
else
else if (DebugLocs.getBytes(Entry).size() <= std::numeric_limits<uint16_t>::max())
Asm->emitInt16(DebugLocs.getBytes(Entry).size());
else {
// The entry is too big to fit into 16 bit, drop it as there is nothing we
// can do.
Asm->emitInt16(0);
return;
}
// Emit the entry.
APByteStreamer Streamer(*Asm);
emitDebugLocEntry(Streamer, Entry, CU);

49
llvm/test/MC/X86/dwarf-size-field-overflow.test Normal file
View File

@ -0,0 +1,49 @@
# This test generates too many debug location entries to fit into 65KB required
# by DWARF < 5. Check that the location is set to 0 instead of crashing.
#
# RUN: %python %s 4000 | llc -filetype=obj -o %t
# RUN: llvm-dwarfdump %t | FileCheck %s
#
# CHECK: 0x0000004d: DW_TAG_formal_parameter
# CHECK-NEXT: DW_AT_location (0x00000000
# CHECK-NEXT: [0x0000000000000000, 0x0000000000000008): )
# CHECK-NEXT: DW_AT_name ("self")
import sys
SKELETON = """define void @test() !dbg !24 {{
{}
call void @foo(), !dbg !34
ret void, !dbg !34
}}
; Function Attrs: nounwind readnone speculatable
declare void @llvm.dbg.value(metadata, metadata, metadata) #0
declare void @foo()
attributes #0 = {{ nounwind readnone speculatable }}
!llvm.dbg.cu = !{{!0}}
!llvm.module.flags = !{{!22}}
!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 4, emissionKind: FullDebug)
!1 = !DIFile(filename: "asdf.c", directory: "bar")
!2 = !{{}}
!6 = !DIModule(scope: null, name: "dag", includePath: "/")
!8 = distinct !DICompositeType(tag: DW_TAG_structure_type, scope: !6, file: !1, line: 36, size: 2384384, elements: !2, runtimeLang: DW_LANG_C)
!22 = !{{i32 2, !"Debug Info Version", i32 3}}
!24 = distinct !DISubprogram(name: "main", linkageName: "main", scope: !6, file: !1, line: 1, type: !25, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
!25 = !DISubroutineType(types: !2)
!30 = !DILocalVariable(name: "self", arg: 1, scope: !24, file: !1, line: 12, type: !8, flags: DIFlagArtificial)
!34 = !DILocation(line: 12, column: 8, scope: !24)
"""
CALL = "call void @llvm.dbg.value(metadata i64 {0}, metadata !30, metadata !DIExpression(DW_OP_LLVM_fragment, {0}, 64)), !dbg !34"
if __name__ == '__main__':
N = int(sys.argv[1])
calls = []
for i in range(0, N):
calls.append(CALL.format(i * 10**12))
print(SKELETON.format('\n'.join(calls)))