[Coverage] Handle CoroutineSuspendExpr correctly (#88898)

This avoids visiting `co_await` or `co_yield` operand 5 times (it is
repeated under transformed awaiter subexpression, and under
`await_ready`, `await_suspend`, and `await_resume` generated call
subexpressions).

clang/lib/CodeGen/CoverageMappingGen.cpp

@@ -1439,6 +1439,10 @@ struct CounterCoverageMappingBuilder
     terminateRegion(S);
   }
 
+  void VisitCoroutineSuspendExpr(const CoroutineSuspendExpr *E) {
+    Visit(E->getOperand());
+  }
+
   void VisitCXXThrowExpr(const CXXThrowExpr *E) {
     extendRegion(E);
     if (E->getSubExpr())

clang/test/CoverageMapping/coroutine.cpp

@@ -32,6 +32,7 @@ struct std::coroutine_traits<int, int> {
     suspend_always final_suspend() noexcept;
     void unhandled_exception() noexcept;
     void return_value(int);
+    suspend_always yield_value(int);
   };
 };
 
@@ -45,3 +46,21 @@ int f1(int x) {       // CHECK-NEXT: File 0, [[@LINE]]:15 -> [[@LINE+8]]:2 = #0
   }                   // CHECK-NEXT: File 0, [[@LINE-2]]:10 -> [[@LINE]]:4 = (#0 - #1)
   co_return x;        // CHECK-NEXT: Gap,File 0, [[@LINE-1]]:4 -> [[@LINE]]:3 = #1
 } // CHECK-NEXT: File 0, [[@LINE-1]]:3 -> [[@LINE-1]]:14 = #1
+
+// CHECK-LABEL: _Z2f2i:
+// CHECK-NEXT: File 0, [[@LINE+1]]:15 -> [[@LINE+15]]:2 = #0
+int f2(int x) {
+// CHECK-NEXT: File 0, [[@LINE+5]]:13 -> [[@LINE+5]]:18 = #0
+// CHECK-NEXT: Branch,File 0, [[@LINE+4]]:13 -> [[@LINE+4]]:18 = #1, (#0 - #1)
+// CHECK-NEXT: Gap,File 0, [[@LINE+3]]:20 -> [[@LINE+3]]:21 = #1
+// CHECK-NEXT: File 0, [[@LINE+2]]:21 -> [[@LINE+2]]:37 = #1
+// CHECK-NEXT: File 0, [[@LINE+1]]:40 -> [[@LINE+1]]:56 = (#0 - #1)
+  co_await (x > 0 ? suspend_always{} : suspend_always{});
+// CHECK-NEXT: File 0, [[@LINE+5]]:12 -> [[@LINE+5]]:17 = #0
+// CHECK-NEXT: Branch,File 0, [[@LINE+4]]:12 -> [[@LINE+4]]:17 = #2, (#0 - #2)
+// CHECK-NEXT: Gap,File 0, [[@LINE+3]]:19 -> [[@LINE+3]]:20 = #2
+// CHECK-NEXT: File 0, [[@LINE+2]]:20 -> [[@LINE+2]]:21 = #2
+// CHECK-NEXT: File 0, [[@LINE+1]]:24 -> [[@LINE+1]]:25 = (#0 - #2)
+  co_yield x > 0 ? 1 : 2;
+  co_return 0;
+}