llvm-project

Commit Graph

Author	SHA1	Message	Date
George Karpenkov	a1c532784d	Fix coverage check for full post-dominator basic blocks. Coverage instrumentation which does not instrument full post-dominators and full-dominators may skip valid paths, as the reasoning for skipping blocks may become circular. This patch fixes that, by only skipping full post-dominators with multiple predecessors, as such predecessors by definition can not be full-dominators. llvm-svn: 303827	2017-05-25 01:41:46 +00:00
George Karpenkov	018472c34a	Revert "Disable coverage opt-out for strong postdominator blocks." This reverts commit 2ed06f05fc10869dd1239cff96fcdea2ee8bf4ef. Buildbots do not like this on Linux. llvm-svn: 303710	2017-05-24 00:29:12 +00:00
George Karpenkov	9017ca290a	Disable coverage opt-out for strong postdominator blocks. Coverage instrumentation has an optimization not to instrument extra blocks, if the pass is already "accounted for" by a successor/predecessor basic block. However (https://github.com/google/sanitizers/issues/783) this reasoning may become circular, which stops valid paths from having coverage. In the worst case this can cause fuzzing to stop working entirely. This change simplifies logic to something which trivially can not have such circular reasoning, as losing valid paths does not seem like a good trade-off for a ~15% decrease in the # of instrumented basic blocks. llvm-svn: 303698	2017-05-23 21:58:54 +00:00

Author

SHA1

Message

Date

George Karpenkov

a1c532784d

Fix coverage check for full post-dominator basic blocks.

Coverage instrumentation which does not instrument full post-dominators
and full-dominators may skip valid paths, as the reasoning for skipping
blocks may become circular.
This patch fixes that, by only skipping
full post-dominators with multiple predecessors, as such predecessors by
definition can not be full-dominators.

llvm-svn: 303827

2017-05-25 01:41:46 +00:00

George Karpenkov

018472c34a

Revert "Disable coverage opt-out for strong postdominator blocks."

This reverts commit 2ed06f05fc10869dd1239cff96fcdea2ee8bf4ef.
Buildbots do not like this on Linux.

llvm-svn: 303710

2017-05-24 00:29:12 +00:00

George Karpenkov

9017ca290a

Disable coverage opt-out for strong postdominator blocks.

Coverage instrumentation has an optimization not to instrument extra
blocks, if the pass is already "accounted for" by a
successor/predecessor basic block.
However (https://github.com/google/sanitizers/issues/783) this
reasoning may become circular, which stops valid paths from having
coverage.
In the worst case this can cause fuzzing to stop working entirely.

This change simplifies logic to something which trivially can not have
such circular reasoning, as losing valid paths does not seem like a
good trade-off for a ~15% decrease in the # of instrumented basic blocks.

llvm-svn: 303698

2017-05-23 21:58:54 +00:00

3 Commits