1 files changed, 21 insertions, 15 deletions
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 5a7455befc3..30cb2238afa 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -2000,8 +2000,9 @@ X86TargetLowering::LowerReturn(SDValue Chain,
     RetOps.push_back(DAG.getRegister(VA.getLocReg(), VA.getLocVT()));
   }
 
-  // All x86 ABIs require that for returning structs by value we copy
+  // The x86-64 ABIs require that for returning structs by value we copy
   // the sret argument into %rax/%eax (depending on ABI) for the return.
+  // Win32 requires us to put the sret argument to %eax as well.
   // We saved the argument into a virtual register in the entry block,
   // so now we copy the value out and into %rax/%eax.
   //
@@ -2010,6 +2011,8 @@ X86TargetLowering::LowerReturn(SDValue Chain,
   // false, then an sret argument may be implicitly inserted in the SelDAG. In
   // either case FuncInfo->setSRetReturnReg() will have been called.
   if (unsigned SRetReg = FuncInfo->getSRetReturnReg()) {
+    assert((Subtarget->is64Bit() || Subtarget->isTargetKnownWindowsMSVC()) &&
+           "No need for an sret register");
     SDValue Val = DAG.getCopyFromReg(Chain, dl, SRetReg, getPointerTy());
 
     unsigned RetValReg
@@ -2431,21 +2434,24 @@ X86TargetLowering::LowerFormalArguments(SDValue Chain,
     InVals.push_back(ArgValue);
   }
 
-  for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
-    // All x86 ABIs require that for returning structs by value we copy the
-    // sret argument into %rax/%eax (depending on ABI) for the return. Save
-    // the argument into a virtual register so that we can access it from the
-    // return points.
-    if (Ins[i].Flags.isSRet()) {
-      unsigned Reg = FuncInfo->getSRetReturnReg();
-      if (!Reg) {
-        MVT PtrTy = getPointerTy();
-        Reg = MF.getRegInfo().createVirtualRegister(getRegClassFor(PtrTy));
-        FuncInfo->setSRetReturnReg(Reg);
+  if (Subtarget->is64Bit() || Subtarget->isTargetKnownWindowsMSVC()) {
+    for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
+      // The x86-64 ABIs require that for returning structs by value we copy
+      // the sret argument into %rax/%eax (depending on ABI) for the return.
+      // Win32 requires us to put the sret argument to %eax as well.
+      // Save the argument into a virtual register so that we can access it
+      // from the return points.
+      if (Ins[i].Flags.isSRet()) {
+        unsigned Reg = FuncInfo->getSRetReturnReg();
+        if (!Reg) {
+          MVT PtrTy = getPointerTy();
+          Reg = MF.getRegInfo().createVirtualRegister(getRegClassFor(PtrTy));
+          FuncInfo->setSRetReturnReg(Reg);
+        }
+        SDValue Copy = DAG.getCopyToReg(DAG.getEntryNode(), dl, Reg, InVals[i]);
+        Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other, Copy, Chain);
+        break;
       }
-      SDValue Copy = DAG.getCopyToReg(DAG.getEntryNode(), dl, Reg, InVals[i]);
-      Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other, Copy, Chain);
-      break;
     }
   }