diff options
| -rw-r--r-- | lib/Target/PowerPC/PPCISelLowering.cpp | 19 | ||||
| -rw-r--r-- | test/CodeGen/PowerPC/emptystruct.ll | 51 |
2 files changed, 70 insertions, 0 deletions
diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp index 541bda5..5768f42 100644 --- a/lib/Target/PowerPC/PPCISelLowering.cpp +++ b/lib/Target/PowerPC/PPCISelLowering.cpp @@ -2091,6 +2091,19 @@ PPCTargetLowering::LowerFormalArguments_64SVR4( // ObjSize is the true size, ArgSize rounded up to multiple of registers. ObjSize = Flags.getByValSize(); ArgSize = ((ObjSize + PtrByteSize - 1)/PtrByteSize) * PtrByteSize; + // Empty aggregate parameters do not take up registers. Examples: + // struct { } a; + // union { } b; + // int c[0]; + // etc. However, we have to provide a place-holder in InVals, so + // pretend we have an 8-byte item at the current address for that + // purpose. + if (!ObjSize) { + int FI = MFI->CreateFixedObject(PtrByteSize, ArgOffset, true); + SDValue FIN = DAG.getFrameIndex(FI, PtrVT); + InVals.push_back(FIN); + continue; + } // All aggregates smaller than 8 bytes must be passed right-justified. if (ObjSize < PtrByteSize) CurArgOffset = CurArgOffset + (PtrByteSize - ObjSize); @@ -3655,6 +3668,12 @@ PPCTargetLowering::LowerCall_64SVR4(SDValue Chain, SDValue Callee, // These are the proper values we need for right-justifying the // aggregate in a parameter register. unsigned Size = Flags.getByValSize(); + + // An empty aggregate parameter takes up no storage and no + // registers. + if (Size == 0) + continue; + // All aggregates smaller than 8 bytes must be passed right-justified. if (Size==1 || Size==2 || Size==4) { EVT VT = (Size==1) ? MVT::i8 : ((Size==2) ? MVT::i16 : MVT::i32); diff --git a/test/CodeGen/PowerPC/emptystruct.ll b/test/CodeGen/PowerPC/emptystruct.ll new file mode 100644 index 0000000..36b4abd --- /dev/null +++ b/test/CodeGen/PowerPC/emptystruct.ll @@ -0,0 +1,51 @@ +; RUN: llc -mcpu=pwr7 -O0 < %s | FileCheck %s + +; This tests correct handling of empty aggregate parameters and return values. +; An empty parameter passed by value does not consume a protocol register or +; a parameter save area doubleword. An empty parameter passed by reference +; is treated as any other pointer parameter. An empty aggregate return value +; is treated as any other aggregate return value, passed via address as a +; hidden parameter in GPR3. In this example, GPR3 contains the return value +; address, GPR4 contains the address of e2, and e1 and e3 are not passed or +; received. + +target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f128:128:128-v128:128:128-n32:64" +target triple = "powerpc64-unknown-linux-gnu" + +%struct.empty = type {} + +define void @callee(%struct.empty* noalias sret %agg.result, %struct.empty* byval %a1, %struct.empty* %a2, %struct.empty* byval %a3) nounwind { +entry: + %a2.addr = alloca %struct.empty*, align 8 + store %struct.empty* %a2, %struct.empty** %a2.addr, align 8 + %0 = load %struct.empty** %a2.addr, align 8 + %1 = bitcast %struct.empty* %agg.result to i8* + %2 = bitcast %struct.empty* %0 to i8* + call void @llvm.memcpy.p0i8.p0i8.i64(i8* %1, i8* %2, i64 0, i32 1, i1 false) + ret void +} + +; CHECK: callee: +; CHECK: std 4, +; CHECK: std 3, +; CHECK-NOT: std 5, +; CHECK-NOT: std 6, +; CHECK: blr + +declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i32, i1) nounwind + +define void @caller(%struct.empty* noalias sret %agg.result) nounwind { +entry: + %e1 = alloca %struct.empty, align 1 + %e2 = alloca %struct.empty, align 1 + %e3 = alloca %struct.empty, align 1 + call void @callee(%struct.empty* sret %agg.result, %struct.empty* byval %e1, %struct.empty* %e2, %struct.empty* byval %e3) + ret void +} + +; CHECK: caller: +; CHECK: addi 4, +; CHECK: std 3, +; CHECK-NOT: std 5, +; CHECK-NOT: std 6, +; CHECK: bl callee |