2 files changed, 20 insertions, 1 deletions
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index e2cc9212597..7dfff5b83a7 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -4049,10 +4049,17 @@ PPCTargetLowering::IsEligibleForTailCallOptimization_64SVR4(
   if (CalleeCC != CallingConv::Fast && CalleeCC != CallingConv::C)
     return false;
 
-  // Functions containing by val parameters are not supported.
+  // Caller contains any byval parameter is not supported.
   if (any_of(Ins, [](const ISD::InputArg &IA) { return IA.Flags.isByVal(); }))
     return false;
 
+  // Callee contains any byval parameter is not supported, too.
+  // Note: This is a quick work around, because in some cases, e.g.
+  // caller's stack size > callee's stack size, we are still able to apply
+  // sibling call optimization. See: https://reviews.llvm.org/D23441#513574
+  if (any_of(Outs, [](const ISD::OutputArg& OA) { return OA.Flags.isByVal(); }))
+    return false;
+
   // No TCO/SCO on indirect call because Caller have to restore its TOC
   if (!isFunctionGlobalAddress(Callee) &&
       !isa<ExternalSymbolSDNode>(Callee))
diff --git a/llvm/test/CodeGen/PowerPC/ppc64-sibcall.ll b/llvm/test/CodeGen/PowerPC/ppc64-sibcall.ll
index e4fe5468e94..474e845a5ba 100644
--- a/llvm/test/CodeGen/PowerPC/ppc64-sibcall.ll
+++ b/llvm/test/CodeGen/PowerPC/ppc64-sibcall.ll
@@ -189,3 +189,15 @@ define void @w_caller(i8* %ptr) {
 ; CHECK-SCO-LABEL: w_caller:
 ; CHECK-SCO: bl w_callee
 }
+
+%struct.byvalTest = type { [8 x i8] }
+@byval = common global %struct.byvalTest zeroinitializer
+
+define void @byval_callee(%struct.byvalTest* byval %ptr) { ret void }
+define void @byval_caller() {
+  tail call void @byval_callee(%struct.byvalTest* byval @byval)
+  ret void
+
+; CHECK-SCO-LABEL: bl byval_callee
+; CHECK-SCO: bl byval_callee
+}