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Bitcode: Stop assuming non-null fields 

When writing the bitcode serialization for the new debug info hierarchy,
I assumed two fields would never be null.

Drop that assumption, since it's brittle (and crashes the
`BitcodeWriter` if wrong), and is a check better left for the verifier
anyway.  (No need for a bitcode upgrade here, since the new hierarchy is
still not in place.)

The fields in question are `MDCompileUnit::getFile()` and
`MDDerivedType::getBaseType()`, the latter of which isn't null in
test/Transforms/Mem2Reg/ConvertDebugInfo2.ll (see !14, a pointer to
nothing).  While the testcase might have bitrotted, there's no reason
for the bitcode format to rely on non-null for metadata operands.

This also fixes a bug in `AsmWriter` where if the `file:` is null it
isn't emitted (caught by the double-round trip in the testcase I'm
adding) -- this is a required field in `LLParser`.

I'll circle back to ConvertDebugInfo2.  Once the specialized nodes are
in place, I'll be trying to turn the debug info verifier back on by
default (in the newer module pass form committed r206300) and throwing
more logic in there.  If the testcase has bitrotted (as opposed to me
not understanding the schema correctly) I'll fix it then.

llvm-svn: 229960
This commit is contained in:
Duncan P. N. Exon Smith 2015-02-20 03:17:58 +00:00
parent 847e05f569
commit ad6eb127c9
4 changed files with 27 additions and 16 deletions
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19
llvm/lib/Bitcode/Reader/BitcodeReader.cpp
View File

@ -1407,8 +1407,8 @@ std::error_code BitcodeReader::ParseMetadata() {
GET_OR_DISTINCT(MDDerivedType, Record[0],
(Context, Record[1], getMDString(Record[2]),
getMDOrNull(Record[3]), Record[4],
getMDOrNull(Record[5]), getMD(Record[6]), Record[7],
Record[8], Record[9], Record[10],
getMDOrNull(Record[5]), getMDOrNull(Record[6]),
Record[7], Record[8], Record[9], Record[10],
getMDOrNull(Record[11]))),
NextMDValueNo++);
break;
@ -1454,13 +1454,14 @@ std::error_code BitcodeReader::ParseMetadata() {
return Error("Invalid record");
MDValueList.AssignValue(
GET_OR_DISTINCT(
MDCompileUnit, Record[0],
(Context, Record[1], getMD(Record[2]), getMDString(Record[3]),
Record[4], getMDString(Record[5]), Record[6],
getMDString(Record[7]), Record[8], getMDOrNull(Record[9]),
getMDOrNull(Record[10]), getMDOrNull(Record[11]),
getMDOrNull(Record[12]), getMDOrNull(Record[13]))),
GET_OR_DISTINCT(MDCompileUnit, Record[0],
(Context, Record[1], getMDOrNull(Record[2]),
getMDString(Record[3]), Record[4],
getMDString(Record[5]), Record[6],
getMDString(Record[7]), Record[8],
getMDOrNull(Record[9]), getMDOrNull(Record[10]),
getMDOrNull(Record[11]), getMDOrNull(Record[12]),
getMDOrNull(Record[13]))),
NextMDValueNo++);
break;
}

4
llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
View File

@ -864,7 +864,7 @@ static void WriteMDDerivedType(const MDDerivedType *N,
Record.push_back(VE.getMetadataOrNullID(N->getFile()));
Record.push_back(N->getLine());
Record.push_back(VE.getMetadataOrNullID(N->getScope()));
Record.push_back(VE.getMetadataID(N->getBaseType()));
Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
Record.push_back(N->getSizeInBits());
Record.push_back(N->getAlignInBits());
Record.push_back(N->getOffsetInBits());
@ -932,7 +932,7 @@ static void WriteMDCompileUnit(const MDCompileUnit *N,
unsigned Abbrev) {
Record.push_back(N->isDistinct());
Record.push_back(N->getSourceLanguage());
Record.push_back(VE.getMetadataID(N->getFile()));
Record.push_back(VE.getMetadataOrNullID(N->getFile()));
Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
Record.push_back(N->isOptimized());
Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));

7
llvm/lib/IR/AsmWriter.cpp
View File

@ -1515,11 +1515,8 @@ static void writeMDCompileUnit(raw_ostream &Out, const MDCompileUnit *N,
Out << Lang;
else
Out << N->getSourceLanguage();
if (N->getFile()) {
Out << FS << "file: ";
writeMetadataAsOperand(Out, N->getFile(), TypePrinter, Machine,
Context);
}
Out << FS << "file: ";
writeMetadataAsOperand(Out, N->getFile(), TypePrinter, Machine, Context);
if (!N->getProducer().empty())
Out << FS << "producer: \"" << N->getProducer() << "\"";
Out << FS << "isOptimized: " << (N->isOptimized() ? "true" : "false");

13
llvm/test/Assembler/metadata-null-operands.ll Normal file
View File

@ -0,0 +1,13 @@
; RUN: llvm-as < %s | llvm-dis | llvm-as | llvm-dis | FileCheck %s
; RUN: verify-uselistorder %s
; Don't crash on null operands. (If/when we add a verify check for these, we
; should disable the verifier for this test and remove this comment; the test
; is still important.)
!named = !{!0, !1}
!0 = !MDDerivedType(tag: DW_TAG_pointer_type, baseType: null)
!1 = !MDCompileUnit(language: DW_LANG_C, file: null)
; CHECK: !named = !{!0, !1}
; CHECK: !0 = !MDDerivedType({{.*}}baseType: null{{.*}})
; CHECK: !1 = !MDCompileUnit({{.*}}file: null{{.*}})