[Clang] Fix crash in coverage of if consteval.

Clang crashes when encountering an `if consteval` statement.
This is the minimum fix not to crash.
The fix is consistent with the current behavior of if constexpr,
which does generate coverage data for the discarded branches.
This is of course not correct and a better solution is
needed for both if constexpr and if consteval.
See https://github.com/llvm/llvm-project/issues/54419.

Fixes #57377

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D132723

1 files changed, 19 insertions, 13 deletions

diff --git a/clang/lib/CodeGen/CoverageMappingGen.cpp b/clang/lib/CodeGen/CoverageMappingGen.cpp
index 0fe084b..836aabf 100644
--- a/clang/lib/CodeGen/CoverageMappingGen.cpp
+++ b/clang/lib/CodeGen/CoverageMappingGen.cpp
@@ -1377,19 +1377,23 @@ struct CounterCoverageMappingBuilder
 
     // Extend into the condition before we propagate through it below - this is
     // needed to handle macros that generate the "if" but not the condition.
-    extendRegion(S->getCond());
+    if (!S->isConsteval())
+      extendRegion(S->getCond());
 
     Counter ParentCount = getRegion().getCounter();
     Counter ThenCount = getRegionCounter(S);
 
-    // Emitting a counter for the condition makes it easier to interpret the
-    // counter for the body when looking at the coverage.
-    propagateCounts(ParentCount, S->getCond());
+    if (!S->isConsteval()) {
+      // Emitting a counter for the condition makes it easier to interpret the
+      // counter for the body when looking at the coverage.
+      propagateCounts(ParentCount, S->getCond());
 
-    // The 'then' count applies to the area immediately after the condition.
-    auto Gap = findGapAreaBetween(S->getRParenLoc(), getStart(S->getThen()));
-    if (Gap)
-      fillGapAreaWithCount(Gap->getBegin(), Gap->getEnd(), ThenCount);
+      // The 'then' count applies to the area immediately after the condition.
+      Optional<SourceRange> Gap =
+          findGapAreaBetween(S->getRParenLoc(), getStart(S->getThen()));
+      if (Gap)
+        fillGapAreaWithCount(Gap->getBegin(), Gap->getEnd(), ThenCount);
+    }
 
     extendRegion(S->getThen());
     Counter OutCount = propagateCounts(ThenCount, S->getThen());
@@ -1398,9 +1402,9 @@ struct CounterCoverageMappingBuilder
     if (const Stmt *Else = S->getElse()) {
       bool ThenHasTerminateStmt = HasTerminateStmt;
       HasTerminateStmt = false;
-
       // The 'else' count applies to the area immediately after the 'then'.
-      Gap = findGapAreaBetween(getEnd(S->getThen()), getStart(Else));
+      Optional<SourceRange> Gap =
+          findGapAreaBetween(getEnd(S->getThen()), getStart(Else));
       if (Gap)
         fillGapAreaWithCount(Gap->getBegin(), Gap->getEnd(), ElseCount);
       extendRegion(Else);
@@ -1416,9 +1420,11 @@ struct CounterCoverageMappingBuilder
       GapRegionCounter = OutCount;
     }
 
-    // Create Branch Region around condition.
-    createBranchRegion(S->getCond(), ThenCount,
-                       subtractCounters(ParentCount, ThenCount));
+    if (!S->isConsteval()) {
+      // Create Branch Region around condition.
+      createBranchRegion(S->getCond(), ThenCount,
+                         subtractCounters(ParentCount, ThenCount));
+    }
   }
 
   void VisitCXXTryStmt(const CXXTryStmt *S) {