ModuleSummaryIndex::print() crashes when printing a thinlto test summary

[Quuxplusone]

Bugzilla Link	PR43048
Status	NEW
Importance	P normal
Reported by	Karthikeyan Manivannan (karthikeyan.m@gmail.com)
Reported on	2019-08-19 11:13:49 -0700
Last modified on	2019-08-19 15:27:28 -0700
Version	trunk
Hardware	Macintosh MacOS X
CC	llvm-bugs@lists.llvm.org
Fixed by commit(s)
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Repro:

Run llvm-as -d on /llvm/test/Assembler/thinlto-summary.ll

Reproduced on master at commit ee6700f69766b57849f483f471387229e495e311

kmanivannan@kmanivannan-mbp:~/local/llvm-project-master/build$ bin/llvm-as  -d
../llvm/test/Assembler/thinlto-summary.ll

Here's the assembly:
; ModuleID = '../llvm/test/Assembler/thinlto-summary.ll'
source_filename = "../llvm/test/Assembler/thinlto-summary.ll"

^0 = module: (path: "thinlto-summary1.o", hash: (1369602428, 2747878711,
259090915, 2507395659, 1141468049))
^1 = module: (path: "thinlto-summary2.o", hash: (2998369023, 4283347029,
1195487472, 2757298015, 1852134156))
^2 = gv: (Stack dump:
0.  Program arguments: bin/llvm-as -d ../llvm/test/Assembler/thinlto-summary.ll
0  llvm-as                  0x0000000106b4afbc
llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 60
1  llvm-as                  0x0000000106b4b579
PrintStackTraceSignalHandler(void*) + 25
2  llvm-as                  0x0000000106b49116 llvm::sys::RunSignalHandlers() +
118
3  llvm-as                  0x0000000106b4f572 SignalHandler(int) + 210
4  libsystem_platform.dylib 0x00007fff66542b5d _sigtramp + 29
5  libsystem_platform.dylib 000000000000000000 _sigtramp + 18446603338799371456
6  llvm-as                  0x0000000106955a89 llvm::Value::getName() const + 25
7  llvm-as                  0x000000010666300b llvm::ValueInfo::name() const +
59
8  llvm-as                  0x000000010666049a (anonymous
namespace)::AssemblyWriter::printSummaryInfo(unsigned int, llvm::ValueInfo
const&) + 90
9  llvm-as                  0x000000010663c550 (anonymous
namespace)::AssemblyWriter::printModuleSummaryIndex() + 1664
10 llvm-as                  0x000000010663be47
llvm::ModuleSummaryIndex::print(llvm::raw_ostream&, bool) const + 119
11 llvm-as                  0x00000001064feac1 main + 1121
12 libdyld.dylib            0x00007fff663573d5 start + 1
13 libdyld.dylib            0x0000000000000003 start + 18446603338801384495
Segmentation fault: 11

[Quuxplusone]

This might be the problem:

llvm-as, via llvm::parseAssemblyWithIndex, builds a ModuleSummaryIndex with HaveGVs always set to true.

The input .ll file I was trying to run 'llvm-as -d' on, has no IR. GlobalValueSummaryInfo.U.GV seem to be set only when GVs in the IR are parsed.

In the absence of IR, and having HaveGVs always set to true, we end up in a situation where a null GlobalValueSummaryInfo.U.GV gets dereferenced.

For this test case, HaveGVs should have been false.

Should there be a way for llvm-as to be able to construct a ModuleSummaryIndex where HaveGVs is set conditionally via an option?