maleadt
commented
2 months ago Looks fixed; updating the test case to current LLVM doesn't result in truncated output.
Closed maleadt closed 2 months ago
maleadt
commented
2 months ago Looks fixed; updating the test case to current LLVM doesn't result in truncated output.
Extended Description
Hi,
I have some code which compiles to an in-memory buffer by wrapping an std::string with an raw_string_ostream and passing it to addPassesToEmitFile. This used to work fine on LLVM 3.5, after wrapping the raw_string_ostream with a formatted_raw_ostream. LLVM 3.7 has changed the interface, requiring a pwrite-able buffer instead. Looking at the raw_pwrite_stream class hierarchy, I decided to wrap the raw_string_ostream with a buffer_ostream. This however yields truncated output (at a seemingly random spot)...
Attached is a relatively large, but straightforward test-case (parse, compile, emit). Compile it with: clang++ -std=c++11 test.cpp $(llvm-config -cxxflags --system-libs --libs all) -L$(llvm-config --libdir) -o test The test-case works on both LLVM 3.7 and 3.5, by means of #ifdef's.
Output on 3.5: // // Generated by LLVM NVPTX Back-End //
.version 3.2 .target sm_20 .address_size 32
.visible .entry dummy(
) {
}
Output on 3.7: // // Generated by LLVM NVPTX Back-End //
.version 3.2 .target sm_20 .address_size 32
.visible .entry dummy(
I tried compiling with ASAN / running with valgrind, but no errors were revealed. Strangely, deleting the PassManager (currently commented) fixes the output! So I'm still thinking it could be a memory error.
I also suspected a flushing issue, but looking at the source code the buffer_ostream should flush when going out-of-scope, and the raw_string_ostream flushes in its str() getter. Adding additional flush() calls did not change the output.
I'm using LLVM 3.5 vanilla and 3.7 from the Arch repositories, on Linux 64bit.