[Coverage] Introduce "partial fold" on BranchRegion (#112694)

Currently both True/False counts were folded. It lost the information,
"It is True or False before folding." It prevented recalling branch
counts in merging template instantiations.

In `llvm-cov`, a folded branch is shown as:

- `[True: n, Folded]`
- `[Folded, False n]`

In the case If `n` is zero, a branch is reported as "uncovered". This is
distinguished from "folded" branch. When folded branches are merged,
`Folded` may be dissolved.

In the coverage map, either `Counter` is `Zero`. Currently both were
`Zero`.

Since "partial fold" has been introduced, either case in `switch` is
omitted as `Folded`.

Each `case:` in `switch` is reported as `[True: n, Folded]`, since
`False` count doesn't show meaningful value.

When `switch` doesn't have `default:`, `switch (Cond)` is reported as
`[Folded, False: n]`, since `True` count was just the sum of `case`(s).
`switch` with `default` can be considered as "the statement that doesn't
have any `False`(s)".

Author: chapuni

Diff for: clang/lib/CodeGen/CoverageMappingGen.cpp

@@ -1098,12 +1098,6 @@ struct CounterCoverageMappingBuilder
     return ExitCount;
   }
 
-  /// Determine whether the given condition can be constant folded.
-  bool ConditionFoldsToBool(const Expr *Cond) {
-    Expr::EvalResult Result;
-    return (Cond->EvaluateAsInt(Result, CVM.getCodeGenModule().getContext()));
-  }
-
   /// Create a Branch Region around an instrumentable condition for coverage
   /// and add it to the function's SourceRegions.  A branch region tracks a
   /// "True" counter and a "False" counter for boolean expressions that
@@ -1133,13 +1127,15 @@ struct CounterCoverageMappingBuilder
       // Alternatively, we can prevent any optimization done via
       // constant-folding by ensuring that ConstantFoldsToSimpleInteger() in
       // CodeGenFunction.c always returns false, but that is very heavy-handed.
-      if (ConditionFoldsToBool(C))
-        popRegions(pushRegion(Counter::getZero(), getStart(C), getEnd(C),
-                              Counter::getZero(), BranchParams));
-      else
-        // Otherwise, create a region with the True counter and False counter.
-        popRegions(pushRegion(TrueCnt, getStart(C), getEnd(C), FalseCnt,
-                              BranchParams));
+      Expr::EvalResult Result;
+      if (C->EvaluateAsInt(Result, CVM.getCodeGenModule().getContext())) {
+        if (Result.Val.getInt().getBoolValue())
+          FalseCnt = Counter::getZero();
+        else
+          TrueCnt = Counter::getZero();
+      }
+      popRegions(
+          pushRegion(TrueCnt, getStart(C), getEnd(C), FalseCnt, BranchParams));
     }
   }
 
@@ -1153,12 +1149,12 @@ struct CounterCoverageMappingBuilder
 
   /// Create a Branch Region around a SwitchCase for code coverage
   /// and add it to the function's SourceRegions.
-  void createSwitchCaseRegion(const SwitchCase *SC, Counter TrueCnt,
-                              Counter FalseCnt) {
+  void createSwitchCaseRegion(const SwitchCase *SC, Counter TrueCnt) {
     // Push region onto RegionStack but immediately pop it (which adds it to
     // the function's SourceRegions) because it doesn't apply to any other
     // source other than the SwitchCase.
-    popRegions(pushRegion(TrueCnt, getStart(SC), SC->getColonLoc(), FalseCnt));
+    popRegions(pushRegion(TrueCnt, getStart(SC), SC->getColonLoc(),
+                          Counter::getZero()));
   }
 
   /// Check whether a region with bounds \c StartLoc and \c EndLoc
@@ -1870,24 +1866,16 @@ struct CounterCoverageMappingBuilder
     const SwitchCase *Case = S->getSwitchCaseList();
     for (; Case; Case = Case->getNextSwitchCase()) {
       HasDefaultCase = HasDefaultCase || isa<DefaultStmt>(Case);
-      CaseCountSum =
-          addCounters(CaseCountSum, getRegionCounter(Case), /*Simplify=*/false);
-      createSwitchCaseRegion(
-          Case, getRegionCounter(Case),
-          subtractCounters(ParentCount, getRegionCounter(Case)));
+      auto CaseCount = getRegionCounter(Case);
+      CaseCountSum = addCounters(CaseCountSum, CaseCount, /*Simplify=*/false);
+      createSwitchCaseRegion(Case, CaseCount);
     }
-    // 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());
-
     // If no explicit default case exists, create a branch region to represent
     // the hidden branch, which will be added later by the CodeGen. This region
     // will be associated with the switch statement's condition.
     if (!HasDefaultCase) {
-      Counter DefaultTrue = subtractCounters(ParentCount, CaseCountSum);
-      Counter DefaultFalse = subtractCounters(ParentCount, DefaultTrue);
-      createBranchRegion(S->getCond(), DefaultTrue, DefaultFalse);
+      Counter DefaultCount = subtractCounters(ParentCount, CaseCountSum);
+      createBranchRegion(S->getCond(), Counter::getZero(), DefaultCount);
     }
   }
 

Diff for: clang/test/CoverageMapping/branch-constfolded.cpp

@@ -5,94 +5,94 @@
 
 // CHECK-LABEL: _Z6fand_0b:
 bool fand_0(bool a) {      // MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:20 = M:3, C:2
-  return false && a;       // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:15 = 0, 0
+  return false && a;       // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:15 = 0, (#0 - #1)
 }                          // CHECK: Branch,File 0, [[@LINE-1]]:19 -> [[@LINE-1]]:20 = #2, (#1 - #2)
 
 // CHECK-LABEL: _Z6fand_1b:
 bool fand_1(bool a) {      // MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:19 = M:3, C:2
   return a && true;        // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:11 = #1, (#0 - #1)
-}                          // CHECK: Branch,File 0, [[@LINE-1]]:15 -> [[@LINE-1]]:19 = 0, 0
+}                          // CHECK: Branch,File 0, [[@LINE-1]]:15 -> [[@LINE-1]]:19 = #2, 0
 
 // CHECK-LABEL: _Z6fand_2bb:
 bool fand_2(bool a, bool b) {// MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:25 = M:4, C:3
-  return false && a && b;  // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:15 = 0, 0
+  return false && a && b;  // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:15 = 0, (#0 - #3)
 }                          // CHECK: Branch,File 0, [[@LINE-1]]:19 -> [[@LINE-1]]:20 = #4, (#3 - #4)
                            // CHECK: Branch,File 0, [[@LINE-2]]:24 -> [[@LINE-2]]:25 = #2, (#1 - #2)
 
 // CHECK-LABEL: _Z6fand_3bb:
 bool fand_3(bool a, bool b) {// MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:24 = M:4, C:3
   return a && true && b;   // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:11 = #3, (#0 - #3)
-}                          // CHECK: Branch,File 0, [[@LINE-1]]:15 -> [[@LINE-1]]:19 = 0, 0
+}                          // CHECK: Branch,File 0, [[@LINE-1]]:15 -> [[@LINE-1]]:19 = #4, 0
                            // CHECK: Branch,File 0, [[@LINE-2]]:23 -> [[@LINE-2]]:24 = #2, (#1 - #2)
 
 // CHECK-LABEL: _Z6fand_4bb:
 bool fand_4(bool a, bool b) {// MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:25 = M:4, C:3
   return a && b && false;  // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:11 = #3, (#0 - #3)
 }                          // CHECK: Branch,File 0, [[@LINE-1]]:15 -> [[@LINE-1]]:16 = #4, (#3 - #4)
-                           // CHECK: Branch,File 0, [[@LINE-2]]:20 -> [[@LINE-2]]:25 = 0, 0
+                           // CHECK: Branch,File 0, [[@LINE-2]]:20 -> [[@LINE-2]]:25 = 0, (#1 - #2)
 
 // CHECK-LABEL: _Z6fand_5b:
 bool fand_5(bool a) {      // MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:23 = M:3, C:2
-  return false && true;    // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:15 = 0, 0
-}                          // CHECK: Branch,File 0, [[@LINE-1]]:19 -> [[@LINE-1]]:23 = 0, 0
+  return false && true;    // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:15 = 0, (#0 - #1)
+}                          // CHECK: Branch,File 0, [[@LINE-1]]:19 -> [[@LINE-1]]:23 = #2, 0
 
 // CHECK-LABEL: _Z6fand_6b:
 bool fand_6(bool a) {      // MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:19 = M:3, C:2
-  return true && a;        // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:14 = 0, 0
+  return true && a;        // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:14 = #1, 0
 }                          // CHECK: Branch,File 0, [[@LINE-1]]:18 -> [[@LINE-1]]:19 = #2, (#1 - #2)
 
 // CHECK-LABEL: _Z6fand_7b:
 bool fand_7(bool a) {      // MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:20 = M:3, C:2
   return a && false;       // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:11 = #1, (#0 - #1)
-}                          // CHECK: Branch,File 0, [[@LINE-1]]:15 -> [[@LINE-1]]:20 = 0, 0
+}                          // CHECK: Branch,File 0, [[@LINE-1]]:15 -> [[@LINE-1]]:20 = 0, (#1 - #2)
 
 // CHECK-LABEL: _Z5for_0b:
 bool for_0(bool a) {       // MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:19 = M:3, C:2
-  return true || a;        // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:14 = 0, 0
+  return true || a;        // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:14 = (#0 - #1), 0
 }                          // CHECK: Branch,File 0, [[@LINE-1]]:18 -> [[@LINE-1]]:19 = (#1 - #2), #2
 
 // CHECK-LABEL: _Z5for_1b:
 bool for_1(bool a) {       // MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:20 = M:3, C:2
   return a || false;       // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:11 = (#0 - #1), #1
-}                          // CHECK: Branch,File 0, [[@LINE-1]]:15 -> [[@LINE-1]]:20 = 0, 0
+}                          // CHECK: Branch,File 0, [[@LINE-1]]:15 -> [[@LINE-1]]:20 = 0, #2
 
 // CHECK-LABEL: _Z5for_2bb:
 bool for_2(bool a, bool b) {// MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:24 = M:4, C:3
-  return true || a || b;   // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:14 = 0, 0
+  return true || a || b;   // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:14 = (#0 - #3), 0
 }                          // CHECK: Branch,File 0, [[@LINE-1]]:18 -> [[@LINE-1]]:19 = (#3 - #4), #4
                            // CHECK: Branch,File 0, [[@LINE-2]]:23 -> [[@LINE-2]]:24 = (#1 - #2), #2
 
 // CHECK-LABEL: _Z5for_3bb:
 bool for_3(bool a, bool b) {// MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:25 = M:4, C:3
   return a || false || b;  // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:11 = (#0 - #3), #3
-}                          // CHECK: Branch,File 0, [[@LINE-1]]:15 -> [[@LINE-1]]:20 = 0, 0
+}                          // CHECK: Branch,File 0, [[@LINE-1]]:15 -> [[@LINE-1]]:20 = 0, #4
                            // CHECK: Branch,File 0, [[@LINE-2]]:24 -> [[@LINE-2]]:25 = (#1 - #2), #2
 
 // CHECK-LABEL: _Z5for_4bb:
 bool for_4(bool a, bool b) {// MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:24 = M:4, C:3
   return a || b || true;   // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:11 = (#0 - #3), #3
 }                          // CHECK: Branch,File 0, [[@LINE-1]]:15 -> [[@LINE-1]]:16 = (#3 - #4), #4
-                           // CHECK: Branch,File 0, [[@LINE-2]]:20 -> [[@LINE-2]]:24 = 0, 0
+                           // CHECK: Branch,File 0, [[@LINE-2]]:20 -> [[@LINE-2]]:24 = (#1 - #2), 0
 
 // CHECK-LABEL: _Z5for_5b:
 bool for_5(bool a) {       // MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:23 = M:3, C:2
-  return true || false;    // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:14 = 0, 0
-}                          // CHECK: Branch,File 0, [[@LINE-1]]:18 -> [[@LINE-1]]:23 = 0, 0
+  return true || false;    // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:14 = (#0 - #1), 0
+}                          // CHECK: Branch,File 0, [[@LINE-1]]:18 -> [[@LINE-1]]:23 = 0, #2
 
 // CHECK-LABEL: _Z5for_6b:
 bool for_6(bool a) {       // MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:20 = M:3, C:2
-  return false || a;       // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:15 = 0, 0
+  return false || a;       // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:15 = 0, #1
 }                          // CHECK: Branch,File 0, [[@LINE-1]]:19 -> [[@LINE-1]]:20 = (#1 - #2), #2
 
 // CHECK-LABEL: _Z5for_7b:
 bool for_7(bool a) {       // MCDC: Decision,File 0, [[@LINE+1]]:10 -> [[@LINE+1]]:19 = M:3, C:2
   return a || true;        // CHECK: Branch,File 0, [[@LINE]]:10 -> [[@LINE]]:11 = (#0 - #1), #1
-}                          // CHECK: Branch,File 0, [[@LINE-1]]:15 -> [[@LINE-1]]:19 = 0, 0
+}                          // CHECK: Branch,File 0, [[@LINE-1]]:15 -> [[@LINE-1]]:19 = (#1 - #2), 0
 
 // CHECK-LABEL: _Z5for_8b:
 bool for_8(bool a) {       // MCDC: Decision,File 0, [[@LINE+3]]:7 -> [[@LINE+3]]:20 = M:3, C:2
-                           // CHECK: Branch,File 0, [[@LINE+2]]:7 -> [[@LINE+2]]:11 = 0, 0
-                           // CHECK: Branch,File 0, [[@LINE+1]]:15 -> [[@LINE+1]]:20 = 0, 0
+                           // CHECK: Branch,File 0, [[@LINE+2]]:7 -> [[@LINE+2]]:11 = #2, 0
+                           // CHECK: Branch,File 0, [[@LINE+1]]:15 -> [[@LINE+1]]:20 = 0, (#2 - #3)
   if (true && false)
       return true;
   else

Diff for: clang/test/CoverageMapping/if.cpp

@@ -14,7 +14,7 @@ struct S {
 // CHECK-LABEL: _Z3foov:
                                 // CHECK-NEXT: [[@LINE+3]]:12 -> [[@LINE+8]]:2 = #0
                                 // CHECK-NEXT: [[@LINE+3]]:15 -> [[@LINE+3]]:19 = #0
-                                // CHECK-NEXT: Branch,File 0, [[@LINE+2]]:15 -> [[@LINE+2]]:19 = 0, 0
+                                // CHECK-NEXT: Branch,File 0, [[@LINE+2]]:15 -> [[@LINE+2]]:19 = #2, 0
 void foo() {                    // CHECK-NEXT: Gap,File 0, [[@LINE+1]]:21 -> [[@LINE+1]]:22 = #2
   if (int j = true ? nop()      // CHECK-NEXT: [[@LINE]]:22 -> [[@LINE]]:27 = #2
                    : nop();     // CHECK-NEXT: [[@LINE]]:22 -> [[@LINE]]:27 = (#0 - #2)
@@ -168,7 +168,7 @@ int main() {                    // CHECK: File 0, [[@LINE]]:12 -> {{[0-9]+}}:2 =
   // GH-45481
   S s;                    
   s.the_prop = 0? 1 : 2;        // CHECK-NEXT: File 0, [[@LINE]]:16 -> [[@LINE]]:17 = #0
-                                // CHECK-NEXT: Branch,File 0, [[@LINE-1]]:16 -> [[@LINE-1]]:17 = 0, 0
+                                // CHECK-NEXT: Branch,File 0, [[@LINE-1]]:16 -> [[@LINE-1]]:17 = 0, (#0 - #7)
                                 // CHECK-NEXT: Gap,File 0, [[@LINE-2]]:18 -> [[@LINE-2]]:19 = #7
                                 // CHECK-NEXT: File 0, [[@LINE-3]]:19 -> [[@LINE-3]]:20 = #7
                                 // CHECK-NEXT: File 0, [[@LINE-4]]:23 -> [[@LINE-4]]:24 = (#0 - #7)

Diff for: clang/test/CoverageMapping/macro-expansion.c

@@ -4,29 +4,29 @@
 // CHECK:      File 1, [[@LINE+7]]:12 -> [[@LINE+7]]:38 = #0
 // CHECK-NEXT: File 1, [[@LINE+6]]:15 -> [[@LINE+6]]:28 = (#0 + #2)
 // CHECK-NEXT: File 1, [[@LINE+5]]:21 -> [[@LINE+5]]:22 = (#0 + #2)
-// CHECK: Branch,File 1, [[@LINE+4]]:21 -> [[@LINE+4]]:22 = 0, 0
+// CHECK: Branch,File 1, [[@LINE+4]]:21 -> [[@LINE+4]]:22 = 0, ((#0 + #2) - #3)
 // CHECK-NEXT: File 1, [[@LINE+3]]:24 -> [[@LINE+3]]:26 = #3
 // CHECK-NEXT: File 1, [[@LINE+2]]:36 -> [[@LINE+2]]:37 = (#0 + #2)
-// CHECK-NEXT: Branch,File 1, [[@LINE+1]]:36 -> [[@LINE+1]]:37 = 0, 0
+// CHECK-NEXT: Branch,File 1, [[@LINE+1]]:36 -> [[@LINE+1]]:37 = 0, #0
 #define M1 do { if (0) {} } while (0)
 // CHECK-NEXT: File 2, [[@LINE+12]]:15 -> [[@LINE+12]]:41 = #0
 // CHECK-NEXT: File 2, [[@LINE+11]]:18 -> [[@LINE+11]]:31 = (#0 + #4)
 // CHECK-NEXT: File 2, [[@LINE+10]]:24 -> [[@LINE+10]]:25 = (#0 + #4)
 // CHECK: File 2, [[@LINE+9]]:27 -> [[@LINE+9]]:29 = #5
 // CHECK-NEXT: File 2, [[@LINE+8]]:39 -> [[@LINE+8]]:40 = (#0 + #4)
-// CHECK-NEXT: Branch,File 2, [[@LINE+7]]:39 -> [[@LINE+7]]:40 = 0, 0
+// CHECK-NEXT: Branch,File 2, [[@LINE+7]]:39 -> [[@LINE+7]]:40 = 0, #0
 // CHECK-NEXT: File 3, [[@LINE+6]]:15 -> [[@LINE+6]]:41 = #0
 // CHECK-NEXT: File 3, [[@LINE+5]]:18 -> [[@LINE+5]]:31 = (#0 + #6)
 // CHECK-NEXT: File 3, [[@LINE+4]]:24 -> [[@LINE+4]]:25 = (#0 + #6)
 // CHECK: File 3, [[@LINE+3]]:27 -> [[@LINE+3]]:29 = #7
 // CHECK-NEXT: File 3, [[@LINE+2]]:39 -> [[@LINE+2]]:40 = (#0 + #6)
-// CHECK-NEXT: Branch,File 3, [[@LINE+1]]:39 -> [[@LINE+1]]:40 = 0, 0
+// CHECK-NEXT: Branch,File 3, [[@LINE+1]]:39 -> [[@LINE+1]]:40 = 0, #0
 #define M2(x) do { if (x) {} } while (0)
 // CHECK-NEXT: File 4, [[@LINE+5]]:15 -> [[@LINE+5]]:38 = #0
 // CHECK-NEXT: File 4, [[@LINE+4]]:18 -> [[@LINE+4]]:28 = (#0 + #8)
 // CHECK-NEXT: Expansion,File 4, [[@LINE+3]]:20 -> [[@LINE+3]]:22 = (#0 + #8)
 // CHECK-NEXT: File 4, [[@LINE+2]]:36 -> [[@LINE+2]]:37 = (#0 + #8)
-// CHECK-NEXT: Branch,File 4, [[@LINE+1]]:36 -> [[@LINE+1]]:37 = 0, 0
+// CHECK-NEXT: Branch,File 4, [[@LINE+1]]:36 -> [[@LINE+1]]:37 = 0, #0
 #define M3(x) do { M2(x); } while (0)
 // CHECK-NEXT: File 5, [[@LINE+4]]:15 -> [[@LINE+4]]:27 = #0
 // CHECK-NEXT: File 5, [[@LINE+3]]:16 -> [[@LINE+3]]:19 = #0

Diff for: clang/test/CoverageMapping/mcdc-scratch-space.c

@@ -3,15 +3,15 @@
 // CHECK: builtin_macro0:
 int builtin_macro0(int a) {
   // CHECK: Decision,File 0, [[@LINE+1]]:11 -> [[@LINE+2]]:15 = M:3, C:2
-  return (__LINE__ // CHECK: Branch,File 0, [[@LINE]]:11 -> [[@LINE]]:11 = 0, 0 [1,2,0]
+  return (__LINE__ // CHECK: Branch,File 0, [[@LINE]]:11 -> [[@LINE]]:11 = #1, 0 [1,2,0]
           && a); //   CHECK: Branch,File 0, [[@LINE]]:14 -> [[@LINE]]:15 = #2, (#1 - #2) [2,0,0]
 }
 
 // CHECK: builtin_macro1:
 int builtin_macro1(int a) {
   // CHECK: Decision,File 0, [[@LINE+1]]:11 -> [[@LINE+2]]:22 = M:3, C:2
   return (a // CHECK: Branch,File 0, [[@LINE]]:11 -> [[@LINE]]:12 = (#0 - #1), #1 [1,0,2]
-          || __LINE__); // CHECK: Branch,File 0, [[@LINE]]:14 -> [[@LINE]]:14 = 0, 0 [2,0,0]
+          || __LINE__); // CHECK: Branch,File 0, [[@LINE]]:14 -> [[@LINE]]:14 = (#1 - #2), 0 [2,0,0]
 }
 
 #define PRE(x) pre_##x

Diff for: clang/test/CoverageMapping/mcdc-system-headers.cpp

@@ -17,10 +17,10 @@
 int func0(int a) {
   // CHECK: Decision,File 0, [[@LINE+3]]:11 -> [[@LINE+3]]:21 = M:3, C:2
   // W_SYS: Expansion,File 0, [[@LINE+2]]:11 -> [[@LINE+2]]:16 = #0 (Expanded file = 1)
-  // X_SYS: Branch,File 0, [[@LINE+1]]:11 -> [[@LINE+1]]:11 = 0, 0 [1,2,0]
+  // X_SYS: Branch,File 0, [[@LINE+1]]:11 -> [[@LINE+1]]:11 = #1, 0 [1,2,0]
   return (CONST && a);
   // CHECK: Branch,File 0, [[@LINE-1]]:20 -> [[@LINE-1]]:21 = #2, (#1 - #2) [2,0,0]
-  // W_SYS: Branch,File 1, [[@LINE-16]]:15 -> [[@LINE-16]]:17 = 0, 0 [1,2,0]
+  // W_SYS: Branch,File 1, [[@LINE-16]]:15 -> [[@LINE-16]]:17 = #1, 0 [1,2,0]
 }
 
 // CHECK: _Z5func1ii: