[clang] 0529da5 - [Coverage] Handle invalid end location of an expression/statement.

[Zequan Wu via cfe-commits]

Author: Zequan Wu
Date: 2023-04-13T10:53:02-04:00
New Revision: 0529da5b948cf168f65bec65b0559139f4f5a426

URL: https://github.com/llvm/llvm-project/commit/0529da5b948cf168f65bec65b0559139f4f5a426
DIFF: https://github.com/llvm/llvm-project/commit/0529da5b948cf168f65bec65b0559139f4f5a426.diff

LOG: [Coverage] Handle invalid end location of an expression/statement.

Fix a crash when an expression/statement can have valid start location but invalid end location in some situations. For example: https://github.com/llvm/llvm-project/blob/llvmorg-16.0.1/clang/lib/Sema/SemaExprCXX.cpp#L1536

This confuses `CounterCoverageMappingBuilder` when popping a region from region
stack as if the end location is a macro or include location.

Reviewed By: hans, aaron.ballman

Differential Revision: https://reviews.llvm.org/D147073

Added: 
    

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/lib/CodeGen/CoverageMappingGen.cpp

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 9abfaf5b2322a..b838858c09179 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -297,6 +297,10 @@ Bug Fixes in This Version
   not a type concept.
 - Fix crash when a doc comment contains a line splicing.
   (`#62054 <https://github.com/llvm/llvm-project/issues/62054>`_)
+- Work around with a clang coverage crash which happens when visiting 
+  expressions/statements with invalid source locations in non-assert builds. 
+  Assert builds may still see assertions triggered from this.
+  (`#62105 <https://github.com/llvm/llvm-project/issues/62105>`_)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

diff  --git a/clang/lib/CodeGen/CoverageMappingGen.cpp b/clang/lib/CodeGen/CoverageMappingGen.cpp
index 426ac39b8767e..bac01c7ff67f2 100644
--- a/clang/lib/CodeGen/CoverageMappingGen.cpp
+++ b/clang/lib/CodeGen/CoverageMappingGen.cpp
@@ -602,6 +602,19 @@ struct CounterCoverageMappingBuilder
       MostRecentLocation = *StartLoc;
     }
 
+    // If either of these locations is invalid, something elsewhere in the
+    // compiler has broken.
+    assert((!StartLoc || StartLoc->isValid()) && "Start location is not valid");
+    assert((!EndLoc || EndLoc->isValid()) && "End location is not valid");
+
+    // However, we can still recover without crashing.
+    // If either location is invalid, set it to std::nullopt to avoid
+    // letting users of RegionStack think that region has a valid start/end
+    // location.
+    if (StartLoc && StartLoc->isInvalid())
+      StartLoc = std::nullopt;
+    if (EndLoc && EndLoc->isInvalid())
+      EndLoc = std::nullopt;
     RegionStack.emplace_back(Count, FalseCount, StartLoc, EndLoc);
 
     return RegionStack.size() - 1;
@@ -624,7 +637,8 @@ struct CounterCoverageMappingBuilder
     assert(RegionStack.size() >= ParentIndex && "parent not in stack");
     while (RegionStack.size() > ParentIndex) {
       SourceMappingRegion &Region = RegionStack.back();
-      if (Region.hasStartLoc()) {
+      if (Region.hasStartLoc() &&
+          (Region.hasEndLoc() || RegionStack[ParentIndex].hasEndLoc())) {
         SourceLocation StartLoc = Region.getBeginLoc();
         SourceLocation EndLoc = Region.hasEndLoc()
                                     ? Region.getEndLoc()
@@ -691,7 +705,7 @@ struct CounterCoverageMappingBuilder
         assert(SM.isWrittenInSameFile(Region.getBeginLoc(), EndLoc));
         assert(SpellingRegion(SM, Region).isInSourceOrder());
         SourceRegions.push_back(Region);
-        }
+      }
       RegionStack.pop_back();
     }
   }