[Coverage][Single] Enable Branch coverage for SwitchStmt

clang/lib/CodeGen/CGStmt.cpp

@@ -2286,6 +2286,18 @@ void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) {
 
   ConditionScope.ForceCleanup();
 
+  // Close the last case (or DefaultBlock).
+  EmitBranch(SwitchExit.getBlock());
+
+  // Insert a False Counter if SwitchStmt doesn't have DefaultStmt.
+  if (getIsCounterPair(S.getCond()).second) {
+    auto *ImplicitDefaultBlock = createBasicBlock("sw.false");
+    EmitBlock(ImplicitDefaultBlock);
+    incrementProfileCounter(UseSkipPath, S.getCond());
+    Builder.CreateBr(SwitchInsn->getDefaultDest());
+    SwitchInsn->setDefaultDest(ImplicitDefaultBlock);
+  }
+
   // Emit continuation.
   EmitBlock(SwitchExit.getBlock(), true);
   incrementProfileCounter(&S);

clang/lib/CodeGen/CoverageMappingGen.cpp

@@ -993,6 +993,25 @@ struct CounterCoverageMappingBuilder
     return Counters;
   }
 
+  /// Returns {TrueCnt,FalseCnt} for "implicit default".
+  /// FalseCnt is considered as the False count on SwitchStmt.
+  std::pair<Counter, Counter>
+  getSwitchImplicitDefaultCounterPair(const Stmt *Cond, Counter ParentCount,
+                                      Counter CaseCountSum) {
+    if (llvm::EnableSingleByteCoverage)
+      // Allocate the new Counter since `subtract(Parent - Sum)` is unavailable.
+      return {Counter::getZero(), // Folded
+              Counter::getCounter(CounterMap[Cond].Skipped = NextCounterNum++)};
+
+    // Simplify is skipped while building the counters above: it can get
+    // really slow on top of switches with thousands of cases. Instead,
+    // trigger simplification by adding zero to the last counter.
+    CaseCountSum =
+        addCounters(CaseCountSum, Counter::getZero(), /*Simplify=*/true);
+
+    return {CaseCountSum, Builder.subtract(ParentCount, CaseCountSum)};
+  }
+
   bool IsCounterEqual(Counter OutCount, Counter ParentCount) {
     if (OutCount == ParentCount)
       return true;
@@ -1922,7 +1941,7 @@ struct CounterCoverageMappingBuilder
       propagateCounts(Counter::getZero(), Body);
     BreakContinue BC = BreakContinueStack.pop_back_val();
 
-    if (!BreakContinueStack.empty() && !llvm::EnableSingleByteCoverage)
+    if (!BreakContinueStack.empty())
       BreakContinueStack.back().ContinueCount = addCounters(
           BreakContinueStack.back().ContinueCount, BC.ContinueCount);
 
@@ -1937,11 +1956,6 @@ struct CounterCoverageMappingBuilder
     MostRecentLocation = getStart(S);
     handleFileExit(ExitLoc);
 
-    // When single byte coverage mode is enabled, do not create branch region by
-    // early returning.
-    if (llvm::EnableSingleByteCoverage)
-      return;
-
     // Create a Branch Region around each Case. Subtract the case's
     // counter from the Parent counter to track the "False" branch count.
     Counter CaseCountSum;
@@ -1956,25 +1970,17 @@ struct CounterCoverageMappingBuilder
     // the hidden branch, which will be added later by the CodeGen. This region
     // will be associated with the switch statement's condition.
     if (!HasDefaultCase) {
-      // Simplify is skipped while building the counters above: it can get
-      // really slow on top of switches with thousands of cases. Instead,
-      // trigger simplification by adding zero to the last counter.
-      CaseCountSum =
-          addCounters(CaseCountSum, Counter::getZero(), /*Simplify=*/true);
-
-      // This is considered as the False count on SwitchStmt.
-      Counter SwitchFalse = subtractCounters(ParentCount, CaseCountSum);
-      createBranchRegion(S->getCond(), CaseCountSum, SwitchFalse);
+      auto Counters = getSwitchImplicitDefaultCounterPair(
+          S->getCond(), ParentCount, CaseCountSum);
+      createBranchRegion(S->getCond(), Counters.first, Counters.second);
     }
   }
 
   void VisitSwitchCase(const SwitchCase *S) {
     extendRegion(S);
 
     SourceMappingRegion &Parent = getRegion();
-    Counter Count = llvm::EnableSingleByteCoverage
-                        ? getRegionCounter(S)
-                        : addCounters(Parent.getCounter(), getRegionCounter(S));
+    Counter Count = addCounters(Parent.getCounter(), getRegionCounter(S));
 
     // Reuse the existing region if it starts at our label. This is typical of
     // the first case in a switch.

clang/test/CoverageMapping/single-byte-counters.cpp

@@ -55,17 +55,17 @@ int testSwitch(int x) { // CHECK-NEXT: File 0, [[@LINE]]:23 -> [[@LINE+20]]:2 =
   switch (x) {
                         // CHECK-NEXT: Gap,File 0, [[@LINE-1]]:14 -> [[@LINE+13]]:15 = 0
   case 1:               // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+3]]:10 = [[C31:#2]]
-
+                        // CHECK-NEXT: Branch,File 0, [[@LINE-1]]:3 -> [[@LINE-1]]:9 = [[C31]], 0
     result = 1;
     break;
                         // CHECK-NEXT: Gap,File 0, [[@LINE-1]]:11 -> [[@LINE+1]]:3 = 0
   case 2:               // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+3]]:10 = [[C32:#3]]
-
+                        // CHECK-NEXT: Branch,File 0, [[@LINE-1]]:3 -> [[@LINE-1]]:9 = [[C32]], 0
     result = 2;
     break;
                         // CHECK-NEXT: Gap,File 0, [[@LINE-1]]:11 -> [[@LINE+1]]:3 = 0
   default:              // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+2]]:15 = [[C3D:#4]]
-
+                        // CHECK-NEXT: Branch,File 0, [[@LINE-1]]:3 -> [[@LINE-1]]:10 = [[C3D]], 0
     result = 0;
   }
                         // CHECK-NEXT: Gap,File 0, [[@LINE-1]]:4 -> [[@LINE+1]]:3 = [[C3E:#1]]

llvm/test/tools/llvm-cov/Inputs/branch-c-general-single.proftext

@@ -192,7 +192,7 @@ jumps
 # Func Hash:
 15051420506203462683
 # Num Counters:
-38
+39
 # Counter Values:
 1
 1
@@ -232,6 +232,7 @@ jumps
 1
 1
 1
+0
 
 main
 # Func Hash:
@@ -263,7 +264,7 @@ switches
 # Func Hash:
 43242458792028222
 # Num Counters:
-29
+30
 # Counter Values:
 1
 1
@@ -294,4 +295,5 @@ switches
 1
 0
 0
+0
 

llvm/test/tools/llvm-cov/Inputs/branch-c-general-single.yaml

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@@ -124,19 +124,19 @@ Symbols:
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     Type:            STT_OBJECT
     Section:         '__llvm_covfun (5)'
     Binding:         STB_WEAK
-    Size:            0x14E
+    Size:            0x181
     Other:           [ STV_HIDDEN ]
   - Name:            __covrec_58A39A89A88AA459u
     Type:            STT_OBJECT

llvm/test/tools/llvm-cov/Inputs/branch-c-general.c

@@ -86,11 +86,11 @@ void jumps() {                  // CHECK: @LINE|{{.*}}jumps()
   while (i < 3) {               // BRCOV: Branch ([[@LINE]]:10): [True: 0, False: 1]
   loop2:
     switch (i) {
-    case 0:                     // BRCOV: Branch ([[@LINE]]:5): [True: 1, Folded]
+    case 0:                     // CHECK: Branch ([[@LINE]]:5): [True: 1, Folded]
       goto first;
-    case 1:                     // BRCOV: Branch ([[@LINE]]:5): [True: 1, Folded]
+    case 1:                     // CHECK: Branch ([[@LINE]]:5): [True: 1, Folded]
       goto second;
-    case 2:                     // BRCOV: Branch ([[@LINE]]:5): [True: 1, Folded]
+    case 2:                     // CHECK: Branch ([[@LINE]]:5): [True: 1, Folded]
       goto third;
     }
   }
@@ -110,30 +110,30 @@ void switches() {               // CHECK: @LINE|{{.*}}switches()
 
   // No cases -> no weights
   switch (weights[0]) {
-  default:                      // BRCOV: Branch ([[@LINE]]:3): [True: 1, Folded]
+  default:                      // CHECK: Branch ([[@LINE]]:3): [True: 1, Folded]
     break;
   }
                                 // BRCOV: Branch ([[@LINE+1]]:63): [True: [[#min(C,15)]], False: 0]
   for (int i = 0, len = sizeof(weights) / sizeof(weights[0]); i < len; ++i) {
     switch (i[weights]) {
-    case 1:                     // BRCOV: Branch ([[@LINE]]:5): [True: 1, Folded]
+    case 1:                     // CHECK: Branch ([[@LINE]]:5): [True: 1, Folded]
       if (i) {}                 // BRCOV: Branch ([[@LINE]]:11): [True: 0, False: 1]
       // fallthrough
-    case 2:                     // BRCOV: Branch ([[@LINE]]:5): [True: [[#min(C,2)]], Folded]
+    case 2:                     // CHECK: Branch ([[@LINE]]:5): [True: [[#min(C,2)]], Folded]
       if (i) {}                 // BRCOV: Branch ([[@LINE]]:11): [True: [[#min(C,2)]], False: 1]
       break;
-    case 3:                     // BRCOV: Branch ([[@LINE]]:5): [True: [[#min(C,3)]], Folded]
+    case 3:                     // CHECK: Branch ([[@LINE]]:5): [True: [[#min(C,3)]], Folded]
       if (i) {}                 // BRCOV: Branch ([[@LINE]]:11): [True: [[#min(C,3)]], False: 0]
       continue;
-    case 4:                     // BRCOV: Branch ([[@LINE]]:5): [True: [[#min(C,4)]], Folded]
+    case 4:                     // CHECK: Branch ([[@LINE]]:5): [True: [[#min(C,4)]], Folded]
       if (i) {}                 // BRCOV: Branch ([[@LINE]]:11): [True: [[#min(C,4)]], False: 0]
       switch (i) {
-      case 6 ... 9:             // BRCOV: Branch ([[@LINE]]:7): [True: [[#min(C,4)]], Folded]
+      case 6 ... 9:             // CHECK: Branch ([[@LINE]]:7): [True: [[#min(C,4)]], Folded]
         if (i) {}               // BRCOV: Branch ([[@LINE]]:13): [True: [[#min(C,4)]], False: 0]
         continue;
       }
 
-    default:                    // BRCOV: Branch ([[@LINE]]:5): [True: [[#min(C,5)]], Folded]
+    default:                    // CHECK: Branch ([[@LINE]]:5): [True: [[#min(C,5)]], Folded]
       if (i == len - 1)         // BRCOV: Branch ([[@LINE]]:11): [True: 1, False: [[#min(C,4)]]]
         return;
     }
@@ -147,29 +147,29 @@ void switches() {               // CHECK: @LINE|{{.*}}switches()
 void big_switch() {             // CHECK: @LINE|{{.*}}big_switch()
   for (int i = 0; i < 32; ++i) {// BRCOV: Branch ([[@LINE]]:19): [True: [[#min(C,32)]], False: 1]
     switch (1 << i) {
-    case (1 << 0):              // BRCOV: Branch ([[@LINE]]:5): [True: 1, Folded]
+    case (1 << 0):              // CHECK: Branch ([[@LINE]]:5): [True: 1, Folded]
       if (i) {}                 // BRCOV: Branch ([[@LINE]]:11): [True: 0, False: 1]
       // fallthrough
-    case (1 << 1):              // BRCOV: Branch ([[@LINE]]:5): [True: 1, Folded]
+    case (1 << 1):              // CHECK: Branch ([[@LINE]]:5): [True: 1, Folded]
       if (i) {}                 // BRCOV: Branch ([[@LINE]]:11): [True: 1, False: 1]
       break;
-    case (1 << 2) ... (1 << 12):// BRCOV: Branch ([[@LINE]]:5): [True: [[#min(C,11)]], Folded]
+    case (1 << 2) ... (1 << 12):// CHECK: Branch ([[@LINE]]:5): [True: [[#min(C,11)]], Folded]
       if (i) {}                 // BRCOV: Branch ([[@LINE]]:11): [True: [[#min(C,11)]], False: 0]
       break;
       // The branch for the large case range above appears after the case body.
 
-    case (1 << 13):             // BRCOV: Branch ([[@LINE]]:5): [True: 1, Folded]
+    case (1 << 13):             // CHECK: Branch ([[@LINE]]:5): [True: 1, Folded]
       if (i) {}                 // BRCOV: Branch ([[@LINE]]:11): [True: 1, False: 0]
       break;
-    case (1 << 14) ... (1 << 28)://BRCOV: Branch ([[@LINE]]:5): [True: [[#min(C,15)]], Folded]
+    case (1 << 14) ... (1 << 28)://CHECK: Branch ([[@LINE]]:5): [True: [[#min(C,15)]], Folded]
       if (i) {}                 // BRCOV: Branch ([[@LINE]]:11): [True: [[#min(C,15)]], False: 0]
       break;
     // The branch for the large case range above appears after the case body.
 
     case (1 << 29) ... ((1 << 29) + 1):
       if (i) {}                 // BRCOV: Branch ([[@LINE]]:11): [True: 1, False: 0]
       break;
-    default:                    // BRCOV: Branch ([[@LINE]]:5): [True: [[#min(C,2)]], Folded]
+    default:                    // CHECK: Branch ([[@LINE]]:5): [True: [[#min(C,2)]], Folded]
       if (i) {}                 // BRCOV: Branch ([[@LINE]]:11): [True: [[#min(C,2)]], False: 0]
       break;
     }