[CodeGen] Don't attempt a tail-call with a non-forwarded explicit sret.
Tailcalls are only OK with forwarded sret pointers. With explicit sret,
one approximation is to check that the pointer isn't an Instruction, as
in that case it might point into some local memory (alloca). That's not
OK with tailcalls.
Explicit sret counterpart to r233409.
Differential Revison: http://reviews.llvm.org/D8510
llvm-svn: 233410
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 67ab548..37f945f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -5556,6 +5556,11 @@
// Skip the first return-type Attribute to get to params.
Entry.setAttributes(&CS, i - CS.arg_begin() + 1);
Args.push_back(Entry);
+
+ // If we have an explicit sret argument that is an Instruction, (i.e., it
+ // might point to function-local memory), we can't meaningfully tail-call.
+ if (Entry.isSRet && isa<Instruction>(V))
+ isTailCall = false;
}
// Check if target-independent constraints permit a tail call here.