Vedant Kumar dd1ea9de2e Reland: [Coverage] Revise format to reduce binary size ... Try again with an up-to-date version of D69471 (99317124 was a stale revision). --- Revise the coverage mapping format to reduce binary size by: 1. Naming function records and marking them `linkonce_odr`, and 2. Compressing filenames. This shrinks the size of llc's coverage segment by 82% (334MB -> 62MB) and speeds up end-to-end single-threaded report generation by 10%. For reference the compressed name data in llc is 81MB (__llvm_prf_names). Rationale for changes to the format: - With the current format, most coverage function records are discarded. E.g., more than 97% of the records in llc are *duplicate* placeholders for functions visible-but-not-used in TUs. Placeholders *are* used to show under-covered functions, but duplicate placeholders waste space. - We reached general consensus about giving (1) a try at the 2017 code coverage BoF [1]. The thinking was that using `linkonce_odr` to merge duplicates is simpler than alternatives like teaching build systems about a coverage-aware database/module/etc on the side. - Revising the format is expensive due to the backwards compatibility requirement, so we might as well compress filenames while we're at it. This shrinks the encoded filenames in llc by 86% (12MB -> 1.6MB). See CoverageMappingFormat.rst for the details on what exactly has changed. Fixes PR34533 [2], hopefully. [1] http://lists.llvm.org/pipermail/llvm-dev/2017-October/118428.html [2] https://bugs.llvm.org/show_bug.cgi?id=34533 Differential Revision: https://reviews.llvm.org/D69471		2020-02-28 18:12:04 -08:00
..
AddressSanitizer	[Local] Do not move around dbg.declares during replaceDbgDeclare	2020-02-13 14:35:02 -08:00
BoundsChecking	Revert "[IRBuilder] Fold consistently for or/and whether constant is LHS or RHS"	2019-07-07 22:12:01 +00:00
DataFlowSanitizer	Migrate function attribute "no-frame-pointer-elim" to "frame-pointer"="all" as cleanups after D56351	2019-12-24 15:57:33 -08:00
HWAddressSanitizer	hwasan: Move .note.hwasan.globals note to hwasan.module_ctor comdat.	2020-01-17 13:40:52 -08:00
InstrOrderFile	Add a module pass for order file instrumentation	2019-02-28 20:13:38 +00:00
InstrProfiling	Reland: [Coverage] Revise format to reduce binary size	2020-02-28 18:12:04 -08:00
MemorySanitizer	Reapply [IRBuilder] Always respect inserter/folder	2020-02-19 20:51:38 +01:00
PoisonChecking	[PoisonCheker] Support for out of bounds operands on shifts + insert/extractelement	2019-07-09 19:26:12 +00:00
SanitizerCoverage	Migrate function attribute "no-frame-pointer-elim"="false" to "frame-pointer"="none" as cleanups after D56351	2019-12-24 16:27:51 -08:00
ThreadSanitizer	Insert module constructors in a module pass	2019-10-11 08:47:03 +00:00
cgprofile.ll	[BFI] Use rounding while computing profile counts.	2018-08-16 00:26:59 +00:00