[Coroutines] Fix code coverage for coroutine

[lxfind]

Summary

Previously, source-based coverage analysis does not work properly for coroutine.
This patch adds processing of coroutine body and co_return in the coverage analysis, so that we can handle them properly.
For coroutine body, we should only look at the actual function body and ignore the compiler-generated things; for co_return, we need to terminate the region similar to return statement.
Added a test, and confirms that it now works properly. (without this patch, the statement after the if statement will be treated wrongly)

[modocache]

Excellent, thanks for this!

[lxfind]

Rebase

[fhahn]

Looks like this causes a bunch of build bot failures, e.g http://lab.llvm.org:8011/builders/clang-x86_64-debian-fast/builds/31465 b

It would be great if you could take a look.

[lxfind]

In D82928#2126018, @fhahn wrote:

Looks like this causes a bunch of build bot failures, e.g http://lab.llvm.org:8011/builders/clang-x86_64-debian-fast/builds/31465 b

It would be great if you could take a look.

Looks like it's creating a tmp file within the test dir. Let me take a look.

[lxfind]

In D82928#2126018, @fhahn wrote:

Looks like this causes a bunch of build bot failures, e.g http://lab.llvm.org:8011/builders/clang-x86_64-debian-fast/builds/31465 b

It would be great if you could take a look.

Let me revert it for now while fixing it. If you could accept: https://reviews.llvm.org/D82984

[lxfind]

In D82928#2126018, @fhahn wrote:

Looks like this causes a bunch of build bot failures, e.g http://lab.llvm.org:8011/builders/clang-x86_64-debian-fast/builds/31465 b

It would be great if you could take a look.

Fix patch in https://reviews.llvm.org/D82986

[thakis]

clang/test/CoverageMapping/coroutine.cpp

1

Since this line is missing an -o /dev/null, it writes a .ll file into the test directory, which lit tries to run as test next time, causing check-clang to fail: http://45.33.8.238/linux/21841/step_7.txt

Please add -o /dev/null, and please also add a RUN: rm -f %S/coroutine.ll to clean up bots (with a fixme to remove that rm line once it's been in the tree for a week or so)

clang/lib/CodeGen/CoverageMappingGen.cpp

struct CounterCoverageMappingBuilder
 
   void VisitReturnStmt(const ReturnStmt *S) {
     extendRegion(S);
     if (S->getRetValue())
       Visit(S->getRetValue());
     terminateRegion(S);
   }
 
+  void VisitCoroutineBodyStmt(const CoroutineBodyStmt *S) {
+    extendRegion(S);
+    Visit(S->getBody());
+  }
+
+  void VisitCoreturnStmt(const CoreturnStmt *S) {
+    extendRegion(S);
+    if (S->getOperand())
+      Visit(S->getOperand());
+    terminateRegion(S);
+  }
+
   void VisitCXXThrowExpr(const CXXThrowExpr *E) {
     extendRegion(E);
     if (E->getSubExpr())
       Visit(E->getSubExpr());
     terminateRegion(E);
   }
 
   void VisitGotoStmt(const GotoStmt *S) { terminateRegion(S); }

clang/test/CoverageMapping/coroutine.cpp

+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fcoroutines-ts -std=c++14 -emit-llvm -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping %s | FileCheck %s
+
+namespace std::experimental {
+template <typename... T>
+struct coroutine_traits;
+
+template <class Promise = void>
+struct coroutine_handle {
+  coroutine_handle() = default;
+  static coroutine_handle from_address(void *) noexcept { return {}; }
+};
+template <>
+struct coroutine_handle<void> {
+  static coroutine_handle from_address(void *) { return {}; }
+  coroutine_handle() = default;
+  template <class PromiseType>
+  coroutine_handle(coroutine_handle<PromiseType>) noexcept {}
+};
+} // namespace std::experimental
+
+struct suspend_always {
+  bool await_ready() noexcept;
+  void await_suspend(std::experimental::coroutine_handle<>) noexcept;
+  void await_resume() noexcept;
+};
+
+template <>
+struct std::experimental::coroutine_traits<int, int> {
+  struct promise_type {
+    int get_return_object();
+    suspend_always initial_suspend();
+    suspend_always final_suspend() noexcept;
+    void return_value(int);
+  };
+};
+
+// CHECK-LABEL: _Z2f1i:
+int f1(int x) {       // CHECK-NEXT: File 0, [[@LINE]]:15 -> [[@LINE+7]]:2 = #0
+  if (x > 42) {       // CHECK-NEXT: File 0, [[@LINE]]:7 -> [[@LINE]]:13 = #0
+    ++x;              // CHECK-NEXT: Gap,File 0, [[@LINE-1]]:14 -> [[@LINE-1]]:15 = #1
+  } else {            // CHECK-NEXT: File 0, [[@LINE-2]]:15 -> [[@LINE]]:4 = #1
+    co_return x + 42; // CHECK-NEXT: Gap,File 0, [[@LINE-1]]:4 -> [[@LINE-1]]:10 = (#0 - #1)
+  }                   // 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]]:2 = #1