commit fafc6e4fdf3673dcf557d6c8ae0c0a4bb3184402
author Erik Pilkington <erik.pilkington@gmail.com> Fri Feb 07 09:37:15 2020 -0800
committer Erik Pilkington <erik.pilkington@gmail.com> Fri Feb 07 14:39:31 2020 -0800
tree fbeb9f4c859ab9b7873a3822bc50cb1daf7aaa1a
parent 5858c9d69f5efa94b721e3d37edadae21cbb77f3

[IRGen] Emit lifetime intrinsics around temporary aggregate argument allocas

These temporaries are only used in the callee, and their memory can be reused
after the call is complete.

rdar://58552124

Differential revision: https://reviews.llvm.org/D74094

clang/lib/CodeGen/CGCall.cpp

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index b55d585..3edcfb2 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -3689,7 +3689,22 @@
     return;
   }
 
-  args.add(EmitAnyExprToTemp(E), type);
+  AggValueSlot ArgSlot = AggValueSlot::ignored();
+  if (hasAggregateEvaluationKind(E->getType())) {
+    ArgSlot = CreateAggTemp(E->getType(), "agg.tmp");
+
+    // Emit a lifetime start/end for this temporary. If the type has a
+    // destructor, then we need to keep it alive. FIXME: We should still be able
+    // to end the lifetime after the destructor returns.
+    if (!E->getType().isDestructedType()) {
+      uint64_t size =
+          CGM.getDataLayout().getTypeAllocSize(ConvertTypeForMem(E->getType()));
+      if (auto *lifetimeSize = EmitLifetimeStart(size, ArgSlot.getPointer()))
+        args.addLifetimeCleanup({ArgSlot.getPointer(), lifetimeSize});
+    }
+  }
+
+  args.add(EmitAnyExpr(E, ArgSlot), type);
 }
 
 QualType CodeGenFunction::getVarArgType(const Expr *Arg) {
@@ -4769,6 +4784,9 @@
   for (CallLifetimeEnd &LifetimeEnd : CallLifetimeEndAfterCall)
     LifetimeEnd.Emit(*this, /*Flags=*/{});
 
+  for (auto &LT : CallArgs.getLifetimeCleanups())
+    EmitLifetimeEnd(LT.Size, LT.Addr);
+
   return Ret;
 }