[clang] [compiler-rt] [Coverage] Fix region termination for GNU statement expressions (PR #130976)

[Fangrui Song via llvm-commits]

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@@ -346,6 +346,12 @@ int elsecondnoret(void) {
   return 0;
 }
 
+// CHECK-LABEL: _Z18statementexprnoretb
+int statementexprnoret(bool crash) {
+  int rc = ({ if (crash) abort(); 0; }); // CHECK-NOT: Gap,File 0, [[@LINE]]:41 -> [[@LINE+1]]:3 = 0
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MaskRay wrote:

CHECK-NOT with a long pattern can easily become stale without being noticed. E.g., the columns 41 and 3 are pretty fragile.

You can use `CHECK(match a previous thing), CHECK-NEXT(match the next thing)` to state that there is no line in between, or add some newlines within the GNU statement expression..

https://github.com/llvm/llvm-project/pull/130976