[llvm] 6400905 - Fix branch coverage merging in FunctionCoverageSummary::get() for instantiation

[Alan Phipps via llvm-commits]

Author: Alan Phipps
Date: 2021-05-11T10:42:40-05:00
New Revision: 6400905a615282c83a2fc6e49e57ff716aa8b4de

URL: https://github.com/llvm/llvm-project/commit/6400905a615282c83a2fc6e49e57ff716aa8b4de
DIFF: https://github.com/llvm/llvm-project/commit/6400905a615282c83a2fc6e49e57ff716aa8b4de.diff

LOG: Fix branch coverage merging in FunctionCoverageSummary::get() for instantiation
groups.

This change corrects the implementation for the branch coverage
summary to do the same thing for branches that is done for lines and regions.
That is, across function instantiations in an instantiation group, the maximum
branch coverage found in any of those instantiations is returned, with the
total number of branches being the same across instantiations.

Differential Revision: https://reviews.llvm.org/D102193

Added: 
    

Modified: 
    llvm/test/tools/llvm-cov/branch-templates.cpp
    llvm/tools/llvm-cov/CoverageSummaryInfo.cpp
    llvm/tools/llvm-cov/CoverageSummaryInfo.h

Removed: 
    


################################################################################
diff  --git a/llvm/test/tools/llvm-cov/branch-templates.cpp b/llvm/test/tools/llvm-cov/branch-templates.cpp
index 750dc7bd58f27..6025f8ae88459 100644
--- a/llvm/test/tools/llvm-cov/branch-templates.cpp
+++ b/llvm/test/tools/llvm-cov/branch-templates.cpp
@@ -1,9 +1,9 @@
 // RUN: llvm-profdata merge %S/Inputs/branch-templates.proftext -o %t.profdata
 // RUN: llvm-cov show --show-expansions --show-branches=count %S/Inputs/branch-templates.o32l -instr-profile %t.profdata -path-equivalence=/tmp,%S %s | FileCheck %s
 // RUN: llvm-cov report --show-branch-summary %S/Inputs/branch-templates.o32l -instr-profile %t.profdata -show-functions -path-equivalence=/tmp,%S %s | FileCheck %s -check-prefix=REPORT
+// RUN: llvm-cov report --show-branch-summary %S/Inputs/branch-templates.o32l -instr-profile %t.profdata -path-equivalence=/tmp,%S %s | FileCheck %s -check-prefix=REPORTFILE
 
 #include <stdio.h>
-
 template<typename T>
 void unused(T x) {
   return;
@@ -45,3 +45,17 @@ int main() {
 // REPORT-NEXT: _Z4funcIfEiT_                     5       2  60.00%         7       3  57.14%         2       1  50.00%
 // REPORT-NEXT: ---
 // REPORT-NEXT: TOTAL                            22       7  68.18%        31      11  64.52%        12       6  50.00%
+
+// Make sure the covered branch tally for the function instantiation group is
+// merged to reflect maximum branch coverage of a single instantiation, just
+// like what is done for lines and regions. Also, the total branch tally
+// summary for an instantiation group should agree with the total number of
+// branches in the definition (In this case, 2 and 6 for func<>() and main(),
+// respectively).  This is returned by: FunctionCoverageSummary::get(const
+// InstantiationGroup &Group, ...)
+
+// REPORTFILE: Filename                      Regions    Missed Regions     Cover   Functions  Missed Functions  Executed       Lines      Missed Lines     Cover    Branches   Missed Branches     Cover
+// REPORTFILE-NEXT: ---
+// REPORTFILE-NEXT: /tmp/branch-templates.cpp          12                 3    75.00%           2                 0   100.00%          17                 4    76.47%           8                 4    50.00%
+// REPORTFILE-NEXT: ---
+// REPORTFILE-NEXT: TOTAL                              12                 3    75.00%           2                 0   100.00%          17                 4    76.47%           8                 4    50.00%

diff  --git a/llvm/tools/llvm-cov/CoverageSummaryInfo.cpp b/llvm/tools/llvm-cov/CoverageSummaryInfo.cpp
index 4a0a86168908f..10e059adeb7d8 100644
--- a/llvm/tools/llvm-cov/CoverageSummaryInfo.cpp
+++ b/llvm/tools/llvm-cov/CoverageSummaryInfo.cpp
@@ -100,11 +100,7 @@ FunctionCoverageSummary::get(const InstantiationGroup &Group,
   for (const auto &FCS : Summaries.drop_front()) {
     Summary.RegionCoverage.merge(FCS.RegionCoverage);
     Summary.LineCoverage.merge(FCS.LineCoverage);
-
-    // Sum branch coverage across instantiation groups for the summary rather
-    // than "merge" the maximum count. This is a clearer view into whether all
-    // created branches are covered.
-    Summary.BranchCoverage += FCS.BranchCoverage;
+    Summary.BranchCoverage.merge(FCS.BranchCoverage);
   }
   return Summary;
 }

diff  --git a/llvm/tools/llvm-cov/CoverageSummaryInfo.h b/llvm/tools/llvm-cov/CoverageSummaryInfo.h
index 4bc1c24a079f2..62e7cad1012b1 100644
--- a/llvm/tools/llvm-cov/CoverageSummaryInfo.h
+++ b/llvm/tools/llvm-cov/CoverageSummaryInfo.h
@@ -123,6 +123,11 @@ class BranchCoverageInfo {
     return *this;
   }
 
+  void merge(const BranchCoverageInfo &RHS) {
+    Covered = std::max(Covered, RHS.Covered);
+    NumBranches = std::max(NumBranches, RHS.NumBranches);
+  }
+
   size_t getCovered() const { return Covered; }
 
   size_t getNumBranches() const { return NumBranches; }