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llvm-cov assertion failure when handling MC/DC that involves macros #80098

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llvm-cov assertion failure when handling MC/DC that involves macros #80098

wants to merge 2 commits into from

Commits on Jan 31, 2024

  1. [Coverage][llvm-cov] Fix failures to handle MC/DC decisions involving… 

    … macros (1/2)

This patch lets MC/DC code regions for the same composite logical
expression get sorted next to each other, so that `llvm-cov show` won't
hit assertion failures.

The problematic cases are mostly when macros are involved:

  (FOO(x) && BAR(y))

   <-R2->    <-R3->
  <-------R1------->

Let's call the full expression Region 1, `FOO(x)` Region 2 and `BAR(y)`
Region 3. If these macros are defined far away from their invocations,
the eventual order of all regions would look like: Region 1, (many other
irrelevant regions), Region 2, Region 3. This will break an assertion in
CoverageMapping::loadFunctionRecord() which assumes branch regions of an
MC/DC decision would immediately follow the decision region itself.

This patch adds a new field `GroupID` to `MCDCParameters` struct, sort
all regions based on this information, and place related MC/DC regions
together. The `GroupID` assignment is included in the other patch to
Clang CodeGen. This patch also disables 3 assertions that's based on the
old sorting criteria.
    @whentojump
    whentojump committed Jan 31, 2024
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  2. [Coverage][clang] Fix failures to handle MC/DC decisions involving ma… 

    …cros (2/2)

This patch lets MC/DC code regions for the same composite logical
expression get sorted next to each other, so that `llvm-cov show` won't
hit assertion failures.

The problematic cases are mostly when macros are involved:

  (FOO(x) && BAR(y))

   <-R2->    <-R3->
  <-------R1------->

Let's call the full expression Region 1, `FOO(x)` Region 2 and `BAR(y)`
Region 3. If these macros are defined far away from their invocations,
the eventual order of all regions would look like: Region 1, (many other
irrelevant regions), Region 2, Region 3. This will break an assertion in
CoverageMapping::loadFunctionRecord() which assumes branch regions of an
MC/DC decision would immediately follow the decision region itself.

An earlier patch adds a new field `GroupID` to `MCDCParameters` struct,
sort all regions based on this information, and place related MC/DC
regions together. This patch let Clang assign the same `GroupID` to
decision- and branch-regions that are related to each other.
    @whentojump
    whentojump committed Jan 31, 2024
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    cd5a338 View commit details
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