[Modules] Record side effect info in EvaluatedStmt (#146468)

All deserialized VarDecl initializers are EvaluatedStmt, but not all
EvaluatedStmt initializers are from a PCH. Calling
`VarDecl::hasInitWithSideEffects` can trigger constant evaluation, but
it's hard to know ahead of time whether that will trigger
deserialization - even if the initializer is fully deserialized, it may
contain a call to a constructor whose body is not deserialized. By
caching the result of `VarDecl::hasInitWithSideEffects` and populating
that cache during deserialization we can guarantee that calling it won't
trigger deserialization regardless of the state of the initializer.
This also reduces memory usage by removing the `InitSideEffectVars` set
in `ASTReader`.

rdar://154717930

1 files changed, 4 insertions, 0 deletions

diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 874b24b..2bd9ae5 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -7320,6 +7320,10 @@ void ASTRecordWriter::AddVarDeclInit(const VarDecl *VD) {
 
   uint64_t Val = 1;
   if (EvaluatedStmt *ES = VD->getEvaluatedStmt()) {
+    // This may trigger evaluation, so run it first
+    if (VD->hasInitWithSideEffects())
+      Val |= 16;
+    assert(ES->CheckedForSideEffects);
     Val |= (ES->HasConstantInitialization ? 2 : 0);
     Val |= (ES->HasConstantDestruction ? 4 : 0);
     APValue *Evaluated = VD->getEvaluatedValue();