[ARM] Do not perform a tail call when the caller returns several values.

The fix is slightly different then x86 (see r216117) because the number of values
attached to a return can vary even for a single returned value (e.g., f64 yields
two returned values).

<rdar://problem/18352998>

llvm-svn: 218076

1 files changed, 11 insertions, 1 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 14cd7d7bd85..ca6b614ce2e 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -2313,9 +2313,15 @@ bool ARMTargetLowering::isUsedByReturnOnly(SDNode *N, SDValue &Chain) const {
       if (Copies.count(UseChain.getNode()))
         // Second CopyToReg
         Copy = *UI;
-      else
+      else {
+        // We are at the top of this chain.
+        // If the copy has a glue operand, we conservatively assume it
+        // isn't safe to perform a tail call.
+        if (UI->getOperand(UI->getNumOperands()-1).getValueType() == MVT::Glue)
+          return false;
         // First CopyToReg
         TCChain = UseChain;
+      }
     }
   } else if (Copy->getOpcode() == ISD::BITCAST) {
     // f32 returned in a single GPR.
@@ -2324,6 +2330,10 @@ bool ARMTargetLowering::isUsedByReturnOnly(SDNode *N, SDValue &Chain) const {
     Copy = *Copy->use_begin();
     if (Copy->getOpcode() != ISD::CopyToReg || !Copy->hasNUsesOfValue(1, 0))
       return false;
+    // If the copy has a glue operand, we conservatively assume it isn't safe to
+    // perform a tail call.
+    if (Copy->getOperand(Copy->getNumOperands()-1).getValueType() == MVT::Glue)
+      return false;
     TCChain = Copy->getOperand(0);
   } else {
     return false;