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[lldb] Fix UB in half2float and add some more tests. 

The added DumpDataExtractorTest uncovered that this is lshifting a negative
integer which upsets ubsan and breaks the sanitizer bot. This patch just
changes the variable we shift to be unsigned and adds a bunch of tests to make
sure this function does what it promises.
This commit is contained in:
Raphael Isemann 2021-05-19 21:35:24 +02:00
parent 50be48b0f3
commit 4b074b49be
2 changed files with 25 additions and 1 deletions
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4
lldb/source/Core/DumpDataExtractor.cpp
View File

@ -52,7 +52,9 @@ static float half2float(uint16_t half) {
float f;
uint32_t u;
} u;
int32_t v = (int16_t)half;
// Sign extend to 4 byte.
int32_t sign_extended = static_cast<int16_t>(half);
uint32_t v = static_cast<uint32_t>(sign_extended);
if (0 == (v & 0x7c00)) {
u.u = v & 0x80007FFFU;

22
lldb/unittests/Core/DumpDataExtractorTest.cpp
View File

@ -174,8 +174,30 @@ TEST(DumpDataExtractorTest, Formats) {
"{0x0000000000000000 0xaaaabbbbccccdddd}");
// See half2float for format details.
// Test zeroes.
TestDump(std::vector<uint16_t>{0x0000, 0x8000},
lldb::Format::eFormatVectorOfFloat16, "{0 -0}");
// Some subnormal numbers.
TestDump(std::vector<uint16_t>{0x0001, 0x8001},
lldb::Format::eFormatVectorOfFloat16, "{5.96046e-08 -5.96046e-08}");
// A full mantisse and empty expontent.
TestDump(std::vector<uint16_t>{0x83ff, 0x03ff},
lldb::Format::eFormatVectorOfFloat16, "{-6.09756e-05 6.09756e-05}");
// Some normal numbers.
TestDump(std::vector<uint16_t>{0b0100001001001000},
lldb::Format::eFormatVectorOfFloat16, "{3.14062}");
TestDump(std::vector<uint16_t>{0xabcd, 0x1234},
lldb::Format::eFormatVectorOfFloat16, "{-0.0609436 0.000757217}");
// Largest and smallest normal number.
TestDump(std::vector<uint16_t>{0x0400, 0x7bff},
lldb::Format::eFormatVectorOfFloat16, "{6.10352e-05 65504}");
// quiet/signaling NaNs.
TestDump(std::vector<uint16_t>{0xffff, 0xffc0, 0x7fff, 0x7fc0},
lldb::Format::eFormatVectorOfFloat16, "{nan nan nan nan}");
// +/-Inf.
TestDump(std::vector<uint16_t>{0xfc00, 0x7c00},
lldb::Format::eFormatVectorOfFloat16, "{-inf inf}");
TestDump(std::vector<float>{std::numeric_limits<float>::min(),
std::numeric_limits<float>::max()},
lldb::Format::eFormatVectorOfFloat32, "{1.17549e-38 3.40282e+38}");