[clang] [compiler-rt] [Coverage] Fix mapping for do-while loops with terminating statements (PR #139777)

[Justin Cady via cfe-commits]

https://github.com/justincady updated https://github.com/llvm/llvm-project/pull/139777

>From be83c3207bf195aa7c6df1ce155402fde5911821 Mon Sep 17 00:00:00 2001
From: Justin Cady <desk at justincady.com>
Date: Tue, 13 May 2025 15:08:45 -0400
Subject: [PATCH] [Coverage] Fix mapping for do-while loops with terminating
 statements

The current region mapping for do-while loops that contain statements
such as break or continue results in inaccurate line coverage reports
for the line following the loop.

This change handles terminating statements the same way that other loop
constructs do, correcting the region mapping for accurate reports. It
also fixes a fragile test relying on exact line numbers.

Fixes #139122
---
 clang/lib/CodeGen/CoverageMappingGen.cpp      |  5 ++---
 .../CoverageMapping/terminate-statements.cpp  | 13 +++++++++++-
 .../test/profile/Linux/coverage-do-while.c    | 21 +++++++++++++++++++
 3 files changed, 35 insertions(+), 4 deletions(-)
 create mode 100644 compiler-rt/test/profile/Linux/coverage-do-while.c

diff --git a/clang/lib/CodeGen/CoverageMappingGen.cpp b/clang/lib/CodeGen/CoverageMappingGen.cpp
index 73811d15979d5..6170dc7f59107 100644
--- a/clang/lib/CodeGen/CoverageMappingGen.cpp
+++ b/clang/lib/CodeGen/CoverageMappingGen.cpp
@@ -1703,14 +1703,13 @@ struct CounterCoverageMappingBuilder
     if (!IsCounterEqual(OutCount, ParentCount)) {
       pushRegion(OutCount);
       GapRegionCounter = OutCount;
+      if (BodyHasTerminateStmt)
+        HasTerminateStmt = true;
     }
 
     // Create Branch Region around condition.
     if (!llvm::EnableSingleByteCoverage)
       createBranchRegion(S->getCond(), BodyCount, BranchCount.Skipped);
-
-    if (BodyHasTerminateStmt)
-      HasTerminateStmt = true;
   }
 
   void VisitForStmt(const ForStmt *S) {
diff --git a/clang/test/CoverageMapping/terminate-statements.cpp b/clang/test/CoverageMapping/terminate-statements.cpp
index ef6b6fd82687d..93d655794ccf5 100644
--- a/clang/test/CoverageMapping/terminate-statements.cpp
+++ b/clang/test/CoverageMapping/terminate-statements.cpp
@@ -348,10 +348,20 @@ int elsecondnoret(void) {
 
 // CHECK-LABEL: _Z18statementexprnoretb:
 int statementexprnoret(bool crash) {
-  int rc = ({ if (crash) abort(); 0; }); // CHECK: File 0, 351:35 -> 352:12 = (#0 - #1)
+  int rc = ({ if (crash) abort(); 0; }); // CHECK: File 0, [[@LINE]]:35 -> [[@LINE+1]]:12 = (#0 - #1)
   return rc;                             // CHECK-NOT: Gap
 }
 
+// CHECK-LABEL: _Z13do_with_breaki:
+int do_with_break(int n) {
+  do {
+    if (n == 87) {
+      break;
+    }               // CHECK: File 0, [[@LINE-2]]:18 -> [[@LINE]]:6 = #2
+  } while (0);      // CHECK: File 0, [[@LINE]]:12 -> [[@LINE]]:13 = ((#0 + #1) - #2)
+  return 0;         // CHECK-NOT: Gap,File 0, [[@LINE-1]]:15
+}
+
 int main() {
   foo(0);
   foo(1);
@@ -375,5 +385,6 @@ int main() {
   abstractcondnoret();
   elsecondnoret();
   statementexprnoret(false);
+  do_with_break(0);
   return 0;
 }
diff --git a/compiler-rt/test/profile/Linux/coverage-do-while.c b/compiler-rt/test/profile/Linux/coverage-do-while.c
new file mode 100644
index 0000000000000..9e112cbc4c6a3
--- /dev/null
+++ b/compiler-rt/test/profile/Linux/coverage-do-while.c
@@ -0,0 +1,21 @@
+// REQUIRES: lld-available
+// XFAIL: powerpc64-target-arch
+
+// RUN: %clangxx_profgen -fuse-ld=lld -fcoverage-mapping -o %t %s
+// RUN: env LLVM_PROFILE_FILE=%t.profraw %run %t
+// RUN: llvm-profdata merge -o %t.profdata %t.profraw
+// RUN: llvm-cov show %t -instr-profile=%t.profdata 2>&1 | FileCheck %s
+
+#include <stdio.h>
+
+// clang-format off
+int main(int argc, char **argv) {           // CHECK:  [[@LINE]]| 1|int main(
+  do {                                      // CHECK:  [[@LINE]]| 1|  do {
+    if (argc == 87) {                       // CHECK:  [[@LINE]]| 1|    if (argc
+      break;                                // CHECK:  [[@LINE]]| 0|      break
+    }                                       // CHECK:  [[@LINE]]| 0|    }
+  } while (0);                              // CHECK:  [[@LINE]]| 1|  } while
+  printf("coverage after do is present\n"); // CHECK:  [[@LINE]]| 1|  printf(
+  return 0;                                 // CHECK:  [[@LINE]]| 1|  return
+}                                           // CHECK:  [[@LINE]]| 1|}
+// clang-format on