release/18.x: [clang][CoverageMapping] do not emit a gap region when either end doesn't have valid source locations (#89564)

[llvmbot]

Backport c1b6cca

Requested by: @whentojump

[llvmbot]

@ZequanWu What do you think about merging this PR to the release branch?

[llvmbot]

@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-codegen

Author: None (llvmbot)

Changes

Backport c1b6cca

Requested by: @whentojump

---

Full diff: https://github.com/llvm/llvm-project/pull/90369.diff

2 Files Affected:

• (modified) clang/lib/CodeGen/CoverageMappingGen.cpp (+8-3)
• (added) clang/test/CoverageMapping/statement-expression.c (+36)

diff --git a/clang/lib/CodeGen/CoverageMappingGen.cpp b/clang/lib/CodeGen/CoverageMappingGen.cpp
index 0c43317642bca4..ae4e6d4c88c02d 100644
--- a/clang/lib/CodeGen/CoverageMappingGen.cpp
+++ b/clang/lib/CodeGen/CoverageMappingGen.cpp
@@ -1207,6 +1207,12 @@ struct CounterCoverageMappingBuilder
   /// Find a valid gap range between \p AfterLoc and \p BeforeLoc.
   std::optional<SourceRange> findGapAreaBetween(SourceLocation AfterLoc,
                                                 SourceLocation BeforeLoc) {
+    // Some statements (like AttributedStmt and ImplicitValueInitExpr) don't
+    // have valid source locations. Do not emit a gap region if this is the case
+    // in either AfterLoc end or BeforeLoc end.
+    if (AfterLoc.isInvalid() || BeforeLoc.isInvalid())
+      return std::nullopt;
+
     // If AfterLoc is in function-like macro, use the right parenthesis
     // location.
     if (AfterLoc.isMacroID()) {
@@ -1370,9 +1376,8 @@ struct CounterCoverageMappingBuilder
     for (const Stmt *Child : S->children())
       if (Child) {
         // If last statement contains terminate statements, add a gap area
-        // between the two statements. Skipping attributed statements, because
-        // they don't have valid start location.
-        if (LastStmt && HasTerminateStmt && !isa<AttributedStmt>(Child)) {
+        // between the two statements.
+        if (LastStmt && HasTerminateStmt) {
           auto Gap = findGapAreaBetween(getEnd(LastStmt), getStart(Child));
           if (Gap)
             fillGapAreaWithCount(Gap->getBegin(), Gap->getEnd(),
diff --git a/clang/test/CoverageMapping/statement-expression.c b/clang/test/CoverageMapping/statement-expression.c
new file mode 100644
index 00000000000000..5f9ab5838af342
--- /dev/null
+++ b/clang/test/CoverageMapping/statement-expression.c
@@ -0,0 +1,36 @@
+// RUN: %clang_cc1 -mllvm -emptyline-comment-coverage=false -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only -main-file-name statement-expression.c %s
+
+// No crash for the following examples, where GNU Statement Expression extension
+// could introduce region terminators (break, goto etc) before implicit
+// initializers in a struct or an array.
+// See https://github.com/llvm/llvm-project/pull/89564
+
+struct Foo {
+  int field1;
+  int field2;
+};
+
+void f1(void) {
+  struct Foo foo = {
+    .field1 = ({
+      switch (0) {
+      case 0:
+        break; // A region terminator
+      }
+      0;
+    }),
+    // ImplicitValueInitExpr introduced here for .field2
+  };
+}
+
+void f2(void) {
+  int arr[3] = {
+    [0] = ({
+        goto L0; // A region terminator
+L0:
+      0;
+    }),
+    // ImplicitValueInitExpr introduced here for subscript [1]
+    [2] = 0,
+  };
+}

[tstellar]

Hi @whentojump (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR.

[whentojump]

Hi @whentojump (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR.

Fixes a Clang assertion failure caused by emitting gap coverage mapping regions between statements with <invalid sloc>.