// src only holds uninitialized values at the moment of the call, meaning that
// the memcpy can be discarded rather than moved.
+ // Lifetime marks shouldn't be operated on.
+ if (Function *F = C->getCalledFunction())
+ if (F->isIntrinsic() && F->getIntrinsicID() == Intrinsic::lifetime_start)
+ return false;
+
// Deliberately get the source and destination with bitcasts stripped away,
// because we'll need to do type comparisons based on the underlying type.
CallSite CS(C);
--- /dev/null
+; RUN: opt < %s -O1 -S | FileCheck %s
+
+; performCallSlotOptzn in MemCpy should not exchange the calls to
+; @llvm.lifetime.start and @llvm.memcpy.
+
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture readonly, i64, i32, i1) #1
+declare void @llvm.lifetime.start(i64, i8* nocapture) #1
+declare void @llvm.lifetime.end(i64, i8* nocapture) #1
+
+define void @_ZN4CordC2EOS_(i8* nocapture dereferenceable(16) %arg1) {
+bb:
+; CHECK-LABEL: @_ZN4CordC2EOS_
+; CHECK-NOT: call void @llvm.lifetime.start
+; CHECK: ret void
+ %tmp = alloca [8 x i8], align 8
+ %tmp5 = bitcast [8 x i8]* %tmp to i8*
+ call void @llvm.lifetime.start(i64 16, i8* %tmp5)
+ %tmp10 = getelementptr inbounds i8, i8* %tmp5, i64 7
+ store i8 0, i8* %tmp10, align 1
+ call void @llvm.memcpy.p0i8.p0i8.i64(i8* %arg1, i8* %tmp5, i64 16, i32 8, i1 false)
+ call void @llvm.lifetime.end(i64 16, i8* %tmp5)
+ ret void
+}
+
+attributes #1 = { argmemonly nounwind }