[Sparc] Allow passing of empty structs.

Passing an empty struct as a function call argument is now supported.

unit tests for various scenarios added.

llvm-svn: 271374

2 files changed, 72 insertions, 11 deletions

diff --git a/llvm/lib/Target/Sparc/SparcISelLowering.cpp b/llvm/lib/Target/Sparc/SparcISelLowering.cpp
index e772a0faa49..0aa68357329 100644
--- a/llvm/lib/Target/Sparc/SparcISelLowering.cpp
+++ b/llvm/lib/Target/Sparc/SparcISelLowering.cpp
@@ -775,16 +775,22 @@ SparcTargetLowering::LowerCall_32(TargetLowering::CallLoweringInfo &CLI,
     unsigned Size = Flags.getByValSize();
     unsigned Align = Flags.getByValAlign();
 
-    int FI = MFI->CreateStackObject(Size, Align, false);
-    SDValue FIPtr = DAG.getFrameIndex(FI, getPointerTy(DAG.getDataLayout()));
-    SDValue SizeNode = DAG.getConstant(Size, dl, MVT::i32);
-
-    Chain = DAG.getMemcpy(Chain, dl, FIPtr, Arg, SizeNode, Align,
-                          false,        // isVolatile,
-                          (Size <= 32), // AlwaysInline if size <= 32,
-                          false,        // isTailCall
-                          MachinePointerInfo(), MachinePointerInfo());
-    ByValArgs.push_back(FIPtr);
+    if (Size > 0U) {
+      int FI = MFI->CreateStackObject(Size, Align, false);
+      SDValue FIPtr = DAG.getFrameIndex(FI, getPointerTy(DAG.getDataLayout()));
+      SDValue SizeNode = DAG.getConstant(Size, dl, MVT::i32);
+
+      Chain = DAG.getMemcpy(Chain, dl, FIPtr, Arg, SizeNode, Align,
+                            false,        // isVolatile,
+                            (Size <= 32), // AlwaysInline if size <= 32,
+                            false,        // isTailCall
+                            MachinePointerInfo(), MachinePointerInfo());
+      ByValArgs.push_back(FIPtr);
+    }
+    else {
+      SDValue nullVal;
+      ByValArgs.push_back(nullVal);
+    }
   }
 
   Chain = DAG.getCALLSEQ_START(Chain, DAG.getIntPtrConstant(ArgsSize, dl, true),
@@ -805,8 +811,12 @@ SparcTargetLowering::LowerCall_32(TargetLowering::CallLoweringInfo &CLI,
     ISD::ArgFlagsTy Flags = Outs[realArgIdx].Flags;
 
     // Use local copy if it is a byval arg.
-    if (Flags.isByVal())
+    if (Flags.isByVal()) {
       Arg = ByValArgs[byvalArgIdx++];
+      if (!Arg) {
+        continue;
+      }
+    }
 
     // Promote the value if needed.
     switch (VA.getLocInfo()) {
diff --git a/llvm/test/CodeGen/SPARC/zerostructcall.ll b/llvm/test/CodeGen/SPARC/zerostructcall.ll
new file mode 100644
index 00000000000..0a8ff65e158
--- /dev/null
+++ b/llvm/test/CodeGen/SPARC/zerostructcall.ll
@@ -0,0 +1,51 @@
+; RUN: llc < %s -march=sparc | FileCheck %s
+
+; CHECK-LABEL: struct_ptr_test
+; CHECK:       call struct_ptr_fn
+; CHECK-NEXT:  st %i0, [%fp+-4]
+; CHECK-NEXT:  ret
+
+%struct.S = type {}
+
+define void @struct_ptr_test(i32 %i) {
+entry:
+  %i.addr = alloca i32, align 4
+  store i32 %i, i32* %i.addr, align 4
+  %0 = bitcast i32* %i.addr to %struct.S*
+  call void @struct_ptr_fn(%struct.S* byval align 1 %0)
+  ret void
+}
+
+declare void @struct_ptr_fn(%struct.S* byval align 1)
+
+; CHECK-LABEL: struct_test
+; CHECK:       call struct_fn
+; CHECK-NEXT:  nop
+; CHECK-NEXT:  ret
+
+%struct.U = type {}
+
+@a = internal global [1 x %struct.U] zeroinitializer, align 1
+
+define void @struct_test() {
+entry:
+  tail call void @struct_fn(%struct.U* byval align 1 getelementptr inbounds ([1 x %struct.U], [1 x %struct.U]* @a, i32 0, i32 0))
+  ret void
+}
+
+; CHECK-LABEL: struct_arg_test
+; CHECK:       call struct_arg_fn
+; CHECK-NEXT:  nop
+; CHECK-NEXT:  ret
+
+declare void @struct_fn(%struct.U* byval align 1)
+
+@b = internal global [1 x %struct.U] zeroinitializer, align 1
+
+define void @struct_arg_test() {
+entry:
+  tail call void @struct_arg_fn(%struct.U* byval align 1 getelementptr inbounds ([1 x %struct.U], [1 x %struct.U]* @b, i32 0, i32 0))
+  ret void
+}
+
+declare void @struct_arg_fn(%struct.U* byval align 1)