[PATCH] D23441: [ppc64] Don't apply sibling call optimization if callee has any byval arg

[Chuang-Yu Cheng via llvm-commits]

cycheng created this revision.
cycheng added reviewers: hfinkel, kbarton, nemanjai, amehsan.
cycheng added subscribers: llvm-commits, tjablin.
Herald added a subscriber: nemanjai.

This is a quick work around, because in some situations, e.g. caller's stack size > callee's stack size, we are still able to apply sibling call optimization even callee has byval arg.

This patch fix: https://llvm.org/bugs/show_bug.cgi?id=28328

https://reviews.llvm.org/D23441

Files:
  lib/Target/PowerPC/PPCISelLowering.cpp
  test/CodeGen/PowerPC/ppc64-sibcall.ll

Index: test/CodeGen/PowerPC/ppc64-sibcall.ll
===================================================================
--- test/CodeGen/PowerPC/ppc64-sibcall.ll
+++ test/CodeGen/PowerPC/ppc64-sibcall.ll
@@ -189,3 +189,15 @@
 ; CHECK-SCO-LABEL: w_caller:
 ; CHECK-SCO: bl w_callee
 }
+
+%struct.byvalTest = type { [8 x i8] }
+ at 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
+}
Index: lib/Target/PowerPC/PPCISelLowering.cpp
===================================================================
--- lib/Target/PowerPC/PPCISelLowering.cpp
+++ lib/Target/PowerPC/PPCISelLowering.cpp
@@ -3964,11 +3964,16 @@
   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 (std::any_of(Ins.begin(), Ins.end(),
                   [](const ISD::InputArg& IA) { return IA.Flags.isByVal(); }))
     return false;
 
+  // Callee contains any byval parameter is not supported, too.
+  if (std::any_of(Outs.begin(), Outs.end(),
+                  [](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))


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