This patch enables general varargs support for the 64-bit PPC SVR4 ABI.

Most of the pieces for this were already in place, but a proper EmitVAArg
is needed for aggregates and complex numbers to be handled.  Although the
va_list for 64-bit PowerPC SVR4 consists of GPRs 3 through 10 together with
the overflow portion of the parameter save area, we can treat va_list as
pointing to contiguous memory for all parameters, since the back end forces
the parameter GPRs to memory for varargs functions.

There is no need at this time to model parameters and return values beyond
what the DefaultABIInfo provides.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@165143 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 102 insertions, 4 deletions

diff --git a/lib/CodeGen/TargetInfo.cpp b/lib/CodeGen/TargetInfo.cpp
index 419ce022e5..5582efab28 100644
--- a/lib/CodeGen/TargetInfo.cpp
+++ b/lib/CodeGen/TargetInfo.cpp
@@ -2581,6 +2581,39 @@ PPC32TargetCodeGenInfo::initDwarfEHRegSizeTable(CodeGen::CodeGenFunction &CGF,
 // PowerPC-64
 
 namespace {
+/// PPC64_SVR4_ABIInfo - The 64-bit PowerPC ELF (SVR4) ABI information.
+class PPC64_SVR4_ABIInfo : public DefaultABIInfo {
+
+public:
+  PPC64_SVR4_ABIInfo(CodeGen::CodeGenTypes &CGT) : DefaultABIInfo(CGT) {}
+
+  // TODO: Could override computeInfo to model the ABI more completely if
+  // it would be helpful.  Example: We might remove the byVal flag from
+  // aggregate arguments that fit in a register to avoid pushing them to
+  // memory on function entry.  Note that this is a performance optimization,
+  // not a compliance issue.  In general we prefer to keep ABI details in
+  // the back end where possible, but modifying an argument flag seems like
+  // a good thing to do before invoking the back end.
+
+  virtual llvm::Value *EmitVAArg(llvm::Value *VAListAddr, 
+                                 QualType Ty,
+                                 CodeGenFunction &CGF) const;
+};
+
+class PPC64_SVR4_TargetCodeGenInfo : public TargetCodeGenInfo {
+public:
+  PPC64_SVR4_TargetCodeGenInfo(CodeGenTypes &CGT)
+    : TargetCodeGenInfo(new PPC64_SVR4_ABIInfo(CGT)) {}
+
+  int getDwarfEHStackPointer(CodeGen::CodeGenModule &M) const {
+    // This is recovered from gcc output.
+    return 1; // r1 is the dedicated stack pointer
+  }
+
+  bool initDwarfEHRegSizeTable(CodeGen::CodeGenFunction &CGF,
+                               llvm::Value *Address) const;
+};
+
 class PPC64TargetCodeGenInfo : public DefaultTargetCodeGenInfo {
 public:
   PPC64TargetCodeGenInfo(CodeGenTypes &CGT) : DefaultTargetCodeGenInfo(CGT) {}
@@ -2596,9 +2629,56 @@ public:
 
 }
 
-bool
-PPC64TargetCodeGenInfo::initDwarfEHRegSizeTable(CodeGen::CodeGenFunction &CGF,
-                                                llvm::Value *Address) const {
+// Based on ARMABIInfo::EmitVAArg, adjusted for 64-bit machine.
+llvm::Value *PPC64_SVR4_ABIInfo::EmitVAArg(llvm::Value *VAListAddr,
+                                           QualType Ty,
+                                           CodeGenFunction &CGF) const {
+  llvm::Type *BP = CGF.Int8PtrTy;
+  llvm::Type *BPP = CGF.Int8PtrPtrTy;
+
+  CGBuilderTy &Builder = CGF.Builder;
+  llvm::Value *VAListAddrAsBPP = Builder.CreateBitCast(VAListAddr, BPP, "ap");
+  llvm::Value *Addr = Builder.CreateLoad(VAListAddrAsBPP, "ap.cur");
+
+  // Handle address alignment for type alignment > 64 bits.  Although
+  // long double normally requires 16-byte alignment, this is not the
+  // case when it is passed as an argument; so handle that special case.
+  const BuiltinType *BT = Ty->getAs<BuiltinType>();
+  unsigned TyAlign = CGF.getContext().getTypeAlign(Ty) / 8;
+
+  if (TyAlign > 8 && (!BT || !BT->isFloatingPoint())) {
+    assert((TyAlign & (TyAlign - 1)) == 0 &&
+           "Alignment is not power of 2!");
+    llvm::Value *AddrAsInt = Builder.CreatePtrToInt(Addr, CGF.Int64Ty);
+    AddrAsInt = Builder.CreateAdd(AddrAsInt, Builder.getInt64(TyAlign - 1));
+    AddrAsInt = Builder.CreateAnd(AddrAsInt, Builder.getInt64(~(TyAlign - 1)));
+    Addr = Builder.CreateIntToPtr(AddrAsInt, BP);
+  }
+
+  // Update the va_list pointer.
+  unsigned SizeInBytes = CGF.getContext().getTypeSize(Ty) / 8;
+  unsigned Offset = llvm::RoundUpToAlignment(SizeInBytes, 8);
+  llvm::Value *NextAddr =
+    Builder.CreateGEP(Addr, llvm::ConstantInt::get(CGF.Int64Ty, Offset),
+                      "ap.next");
+  Builder.CreateStore(NextAddr, VAListAddrAsBPP);
+
+  // If the argument is smaller than 8 bytes, it is right-adjusted in
+  // its doubleword slot.  Adjust the pointer to pick it up from the
+  // correct offset.
+  if (SizeInBytes < 8) {
+    llvm::Value *AddrAsInt = Builder.CreatePtrToInt(Addr, CGF.Int64Ty);
+    AddrAsInt = Builder.CreateAdd(AddrAsInt, Builder.getInt64(8 - SizeInBytes));
+    Addr = Builder.CreateIntToPtr(AddrAsInt, BP);
+  }
+
+  llvm::Type *PTy = llvm::PointerType::getUnqual(CGF.ConvertType(Ty));
+  return Builder.CreateBitCast(Addr, PTy);
+}
+
+static bool
+PPC64_initDwarfEHRegSizeTable(CodeGen::CodeGenFunction &CGF,
+                              llvm::Value *Address) {
   // This is calculated from the LLVM and GCC tables and verified
   // against gcc output.  AFAIK all ABIs use the same encoding.
 
@@ -2637,6 +2717,21 @@ PPC64TargetCodeGenInfo::initDwarfEHRegSizeTable(CodeGen::CodeGenFunction &CGF,
   return false;
 }
 
+bool
+PPC64_SVR4_TargetCodeGenInfo::initDwarfEHRegSizeTable(
+  CodeGen::CodeGenFunction &CGF,
+  llvm::Value *Address) const {
+
+  return PPC64_initDwarfEHRegSizeTable(CGF, Address);
+}
+
+bool
+PPC64TargetCodeGenInfo::initDwarfEHRegSizeTable(CodeGen::CodeGenFunction &CGF,
+                                                llvm::Value *Address) const {
+
+  return PPC64_initDwarfEHRegSizeTable(CGF, Address);
+}
+
 //===----------------------------------------------------------------------===//
 // ARM ABI Implementation
 //===----------------------------------------------------------------------===//
@@ -3878,7 +3973,10 @@ const TargetCodeGenInfo &CodeGenModule::getTargetCodeGenInfo() {
   case llvm::Triple::ppc:
     return *(TheTargetCodeGenInfo = new PPC32TargetCodeGenInfo(Types));
   case llvm::Triple::ppc64:
-    return *(TheTargetCodeGenInfo = new PPC64TargetCodeGenInfo(Types));
+    if (Triple.isOSBinFormatELF())
+      return *(TheTargetCodeGenInfo = new PPC64_SVR4_TargetCodeGenInfo(Types));
+    else
+      return *(TheTargetCodeGenInfo = new PPC64TargetCodeGenInfo(Types));
 
   case llvm::Triple::nvptx:
   case llvm::Triple::nvptx64: