[Comgr] Materialize header inputs in the VFS instead of on disk - #3842
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[Comgr] Materialize header inputs in the VFS instead of on disk#3842chinmaydd wants to merge 1 commit into
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This was referenced Aug 10, 2026
Includes, precompiled headers and opencl-c-base.h were written to real temp files on every compile even though the in-memory VFS is enabled by default. These paths are read back only through Clang's FileManager, which is built on the driver's OverlayFS, so they can be served from memory. Source, bitcode and link inputs stay on disk: cc1as, lld, the offload bundler and the command cache's input hashing all read the real filesystem. Also stop getFilePath running fs::create_directories on every path it builds; only the three paths the in-process driver writes need it, and outputToFile already creates the parent for the paths Comgr writes. And take ownership of the output buffer in inputFromFile rather than malloc+memcpy every artifact a second time. 60 OpenCL preprocess actions with 24 8KB includes: 1521 ms -> ~1400 ms. Co-authored-by: Cursor <cursoragent@cursor.com>
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This is third in a series of PRs that improves Comgr.
Includes, precompiled headers and opencl-c-base.h were written to real temp files on every compile even though the in-memory VFS is enabled by default. These paths are read back only through Clang's FileManager, which is built on the driver's OverlayFS, so they can be served from memory. Source, bitcode and link inputs stay on disk: cc1as, lld, the offload bundler and the command cache's input hashing all read the real filesystem.
Also stop
getFilePathrunningfs::create_directorieson every path it builds; only the three paths the in-process driver writes need it, andoutputToFilealready creates the parent for the paths Comgr writes. And take ownership of the output buffer ininputFromFilerather than malloc+memcpy every artifact a second time.60 OpenCL preprocess actions with 24 8KB includes: 1521 ms -> ~1400 ms.
[1/3] <- #3840
[2/3] <- #3841
[3/3] <- you are here