[Coverage] Make SingleByteCoverage work consistent to merging

- Round `Counts` as 1/0
- Confirm both `ExecutionCount` and `AltExecutionCount` are in range.

Author: chapuni

compiler-rt/test/profile/instrprof-block-coverage.c

@@ -49,4 +49,4 @@ int main(int argc, char *argv[]) {
 
 // CHECK-ERROR-NOT: warning: {{.*}}: Found inconsistent block coverage
 
-// COUNTS: Maximum function count: 4
+// COUNTS: Maximum function count: 1

compiler-rt/test/profile/instrprof-entry-coverage.c

@@ -36,4 +36,4 @@ int main(int argc, char *argv[]) {
 // CHECK-DAG: foo
 // CHECK-DAG: bar
 
-// COUNTS: Maximum function count: 2
+// COUNTS: Maximum function count: 1

llvm/include/llvm/ProfileData/InstrProf.h

@@ -830,6 +830,7 @@ struct InstrProfValueSiteRecord {
 /// Profiling information for a single function.
 struct InstrProfRecord {
   std::vector<uint64_t> Counts;
+  bool SingleByteCoverage = false;
   std::vector<uint8_t> BitmapBytes;
 
   InstrProfRecord() = default;
@@ -839,13 +840,15 @@ struct InstrProfRecord {
       : Counts(std::move(Counts)), BitmapBytes(std::move(BitmapBytes)) {}
   InstrProfRecord(InstrProfRecord &&) = default;
   InstrProfRecord(const InstrProfRecord &RHS)
-      : Counts(RHS.Counts), BitmapBytes(RHS.BitmapBytes),
+      : Counts(RHS.Counts), SingleByteCoverage(RHS.SingleByteCoverage),
+        BitmapBytes(RHS.BitmapBytes),
         ValueData(RHS.ValueData
                       ? std::make_unique<ValueProfData>(*RHS.ValueData)
                       : nullptr) {}
   InstrProfRecord &operator=(InstrProfRecord &&) = default;
   InstrProfRecord &operator=(const InstrProfRecord &RHS) {
     Counts = RHS.Counts;
+    SingleByteCoverage = RHS.SingleByteCoverage;
     BitmapBytes = RHS.BitmapBytes;
     if (!RHS.ValueData) {
       ValueData = nullptr;

llvm/lib/ProfileData/Coverage/CoverageMapping.cpp

@@ -874,6 +874,9 @@ Error CoverageMapping::loadFunctionRecord(
       consumeError(std::move(E));
       return Error::success();
     }
+    assert(!SingleByteCoverage ||
+           (0 <= *ExecutionCount && *ExecutionCount <= 1 &&
+            0 <= *AltExecutionCount && *AltExecutionCount <= 1));
     Function.pushRegion(Region, *ExecutionCount, *AltExecutionCount);
 
     // Record ExpansionRegion.

llvm/lib/ProfileData/InstrProf.cpp

@@ -952,7 +952,7 @@ void InstrProfRecord::merge(InstrProfRecord &Other, uint64_t Weight,
       Value = getInstrMaxCountValue();
       Overflowed = true;
     }
-    Counts[I] = Value;
+    Counts[I] = (SingleByteCoverage && Value != 0 ? 1 : Value);
     if (Overflowed)
       Warn(instrprof_error::counter_overflow);
   }

llvm/lib/ProfileData/InstrProfReader.cpp

@@ -743,6 +743,7 @@ Error RawInstrProfReader<IntPtrT>::readRawCounts(
 
   Record.Counts.clear();
   Record.Counts.reserve(NumCounters);
+  Record.SingleByteCoverage = hasSingleByteCoverage();
   for (uint32_t I = 0; I < NumCounters; I++) {
     const char *Ptr =
         CountersStart + CounterBaseOffset + I * getCounterTypeSize();