This patch solves a problem with passing varargs parameters under the PPC64
ELF ABI.
A varargs parameter consisting of a single-precision floating-point value,
or of a single-element aggregate containing a single-precision floating-point
value, must be passed in the low-order (rightmost) four bytes of the
doubleword stack slot reserved for that parameter. If there are GPR protocol
registers remaining, the parameter must also be mirrored in the low-order
four bytes of the reserved GPR.
Prior to this patch, such parameters were being passed in the high-order
four bytes of the stack slot and the mirrored GPR.
The patch adds a new test case to verify the correct code generation.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166968 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp
index cbb043c..f277910 100644
--- a/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -3751,7 +3751,17 @@
RegsToPass.push_back(std::make_pair(FPR[FPR_idx++], Arg));
if (isVarArg) {
- SDValue Store = DAG.getStore(Chain, dl, Arg, PtrOff,
+ // A single float or an aggregate containing only a single float
+ // must be passed right-justified in the stack doubleword, and
+ // in the GPR, if one is available.
+ SDValue StoreOff;
+ if (Arg.getValueType().getSimpleVT().SimpleTy == MVT::f32) {
+ SDValue ConstFour = DAG.getConstant(4, PtrOff.getValueType());
+ StoreOff = DAG.getNode(ISD::ADD, dl, PtrVT, PtrOff, ConstFour);
+ } else
+ StoreOff = PtrOff;
+
+ SDValue Store = DAG.getStore(Chain, dl, Arg, StoreOff,
MachinePointerInfo(), false, false, 0);
MemOpChains.push_back(Store);