Fix bug 14779 for passing anonymous aggregates [patch by Kai Nacke].

The PPC backend doesn't handle these correctly.  This patch uses logic
similar to that in the X86 and ARM backends to track these arguments
properly.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175635 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp
index f3ef38a..338d73f 100644
--- a/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -2163,13 +2163,16 @@
   SmallVector<SDValue, 8> MemOps;
   unsigned nAltivecParamsAtEnd = 0;
   Function::const_arg_iterator FuncArg = MF.getFunction()->arg_begin();
-  for (unsigned ArgNo = 0, e = Ins.size(); ArgNo != e; ++ArgNo, ++FuncArg) {
+  unsigned CurArgIdx = 0;
+  for (unsigned ArgNo = 0, e = Ins.size(); ArgNo != e; ++ArgNo) {
     SDValue ArgVal;
     bool needsLoad = false;
     EVT ObjectVT = Ins[ArgNo].VT;
     unsigned ObjSize = ObjectVT.getSizeInBits()/8;
     unsigned ArgSize = ObjSize;
     ISD::ArgFlagsTy Flags = Ins[ArgNo].Flags;
+    std::advance(FuncArg, Ins[ArgNo].OrigArgIndex - CurArgIdx);
+    CurArgIdx = Ins[ArgNo].OrigArgIndex;
 
     unsigned CurArgOffset = ArgOffset;
 
@@ -2504,6 +2507,9 @@
 
   SmallVector<SDValue, 8> MemOps;
   unsigned nAltivecParamsAtEnd = 0;
+  // FIXME: FuncArg and Ins[ArgNo] must reference the same argument.
+  // When passing anonymous aggregates, this is currently not true.
+  // See LowerFormalArguments_64SVR4 for a fix.
   Function::const_arg_iterator FuncArg = MF.getFunction()->arg_begin();
   for (unsigned ArgNo = 0, e = Ins.size(); ArgNo != e; ++ArgNo, ++FuncArg) {
     SDValue ArgVal;