[Coverage] Introduce the type `CounterPair` for RegionCounterMap. NFC. (#112724)

`CounterPair` can hold `<uint32_t, uint32_t>` instead of current
`unsigned`, to hold also the counter number of SkipPath. For now, this
change provides the skeleton and only `CounterPair::Executed` is used.

Each counter number can have `None` to suppress emitting counter
increment. 2nd element `Skipped` is initialized as `None` by default,
since most `Stmt*` don't have a pair of counters.

This change also provides stubs for the verifier. I'll provide the impl
of verifier for `+Asserts` later.

`markStmtAsUsed(bool, Stmt*)` may be used to inform that other side
counter may not emitted.

`markStmtMaybeUsed(S)` may be used for the `Stmt` and its inner will be
excluded for emission in the case of skipping by constant folding. I put
it into places where I found.

`verifyCounterMap()` will check the coverage map and the counter map,
and can be used to report inconsistency.

These verifier methods shall be eliminated in `-Asserts`.


https://discourse.llvm.org/t/rfc-integrating-singlebytecoverage-with-branch-coverage/82492

1 files changed, 3 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/CoverageMappingGen.cpp b/clang/lib/CodeGen/CoverageMappingGen.cpp
index dfffa12..f091577 100644
--- a/clang/lib/CodeGen/CoverageMappingGen.cpp
+++ b/clang/lib/CodeGen/CoverageMappingGen.cpp
@@ -882,7 +882,7 @@ struct CounterCoverageMappingBuilder
     : public CoverageMappingBuilder,
       public ConstStmtVisitor<CounterCoverageMappingBuilder> {
   /// The map of statements to count values.
-  llvm::DenseMap<const Stmt *, unsigned> &CounterMap;
+  llvm::DenseMap<const Stmt *, CounterPair> &CounterMap;
 
   MCDC::State &MCDCState;
 
@@ -931,7 +931,7 @@ struct CounterCoverageMappingBuilder
   ///
   /// This should only be called on statements that have a dedicated counter.
   Counter getRegionCounter(const Stmt *S) {
-    return Counter::getCounter(CounterMap[S]);
+    return Counter::getCounter(CounterMap[S].Executed);
   }
 
   struct BranchCounterPair {
@@ -1457,7 +1457,7 @@ struct CounterCoverageMappingBuilder
 
   CounterCoverageMappingBuilder(
       CoverageMappingModuleGen &CVM,
-      llvm::DenseMap<const Stmt *, unsigned> &CounterMap,
+      llvm::DenseMap<const Stmt *, CounterPair> &CounterMap,
       MCDC::State &MCDCState, SourceManager &SM, const LangOptions &LangOpts)
       : CoverageMappingBuilder(CVM, SM, LangOpts), CounterMap(CounterMap),
         MCDCState(MCDCState), MCDCBuilder(CVM.getCodeGenModule(), MCDCState) {}