PhD Seminar • Software Engineering | Software Testing • Compilation Consistency Modulo Debug Information

Please note: This PhD seminar will take place in DC 1304 and virtually over Zoom.

Yongqiang (Victor) Tian, PhD candidate
David R. Cheriton School of Computer Science

Supervisor: Professor Chengnian Sun

Compilation Consistency Modulo Debug Information (CCMD) is an essential compiler property that a production compiler should support: the compiler should emit the same machine code regardless of enabling debug information. CCMD is vital to developers’ experiences with debugging a production binary containing no debug information. To debug such a binary, developers need to build another binary with the same compiler flags and enable debug information. Without CCMD, the machine code in the latter binary will be different, which can confuse the debugger, hide the bug, or even cause a miscompilation (as GCC once did with the Linux Kernel).

In this seminar, we will introduce the validation of CCMD, a new research problem that has been overlooked for decades despite its importance. We will introduce the first testing technique Dfusor to automatically validate CCMD for C compilers. At the high level, given a compilable program P as a seed, Dfusor automatically generates compilable program variants via multiple effective program transformations. Such variants can cause a compiler to emit more debug information than it would when compiling P, thus exercising more code paths in the compiler and increasing the chance to find CCMD bugs. Within 10 months of development and intermittent testing, Dfusor has found 23 bugs (9 in GCC and 14 in Clang), with 3 confirmed and 18 fixed.

To attend this seminar in person, please go to DC 1304. You can also attend virtually using Zoom at https://uwaterloo.zoom.us/j/91647800653.