[PATCH] [mips] Defer va_arg expansion to the backend.

[Daniel Sanders]

Hi sstankovic,

This patch causes clang to emit va_arg instructions to the backend instead of
expanding them into an implementation itself. The backend already implements
va_arg since this is necessary for NaCl so this patch is removing redundant
code.

Together with the llvm patch (D4556) that accounts for the effect of endianness
on the expansion of va_arg, this fixes PR19612.

Depends on D4556

http://reviews.llvm.org/D4742

Files:
  lib/CodeGen/TargetInfo.cpp
  lib/Driver/.ToolChains.cpp.swo
  lib/Driver/.Tools.cpp.swo
  test/CodeGen/mips-vaarg.c

Index: lib/CodeGen/TargetInfo.cpp
===================================================================
--- lib/CodeGen/TargetInfo.cpp
+++ lib/CodeGen/TargetInfo.cpp
@@ -5560,39 +5560,7 @@
 
 llvm::Value* MipsABIInfo::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");
-  int64_t TypeAlign = getContext().getTypeAlign(Ty) / 8;
-  llvm::Type *PTy = llvm::PointerType::getUnqual(CGF.ConvertType(Ty));
-  llvm::Value *AddrTyped;
-  unsigned PtrWidth = getTarget().getPointerWidth(0);
-  llvm::IntegerType *IntTy = (PtrWidth == 32) ? CGF.Int32Ty : CGF.Int64Ty;
-
-  if (TypeAlign > MinABIStackAlignInBytes) {
-    llvm::Value *AddrAsInt = CGF.Builder.CreatePtrToInt(Addr, IntTy);
-    llvm::Value *Inc = llvm::ConstantInt::get(IntTy, TypeAlign - 1);
-    llvm::Value *Mask = llvm::ConstantInt::get(IntTy, -TypeAlign);
-    llvm::Value *Add = CGF.Builder.CreateAdd(AddrAsInt, Inc);
-    llvm::Value *And = CGF.Builder.CreateAnd(Add, Mask);
-    AddrTyped = CGF.Builder.CreateIntToPtr(And, PTy);
-  }
-  else
-    AddrTyped = Builder.CreateBitCast(Addr, PTy);  
-
-  llvm::Value *AlignedAddr = Builder.CreateBitCast(AddrTyped, BP);
-  TypeAlign = std::max((unsigned)TypeAlign, MinABIStackAlignInBytes);
-  uint64_t Offset =
-    llvm::RoundUpToAlignment(CGF.getContext().getTypeSize(Ty) / 8, TypeAlign);
-  llvm::Value *NextAddr =
-    Builder.CreateGEP(AlignedAddr, llvm::ConstantInt::get(IntTy, Offset),
-                      "ap.next");
-  Builder.CreateStore(NextAddr, VAListAddrAsBPP);
-  
-  return AddrTyped;
+  return nullptr;
 }
 
 bool
Index: test/CodeGen/mips-vaarg.c
===================================================================
--- /dev/null
+++ test/CodeGen/mips-vaarg.c
@@ -0,0 +1,18 @@
+// RUN: %clang -target mips-unknown-linux -S -o - -emit-llvm %s | FileCheck %s
+// RUN: %clang -target mipsel-unknown-linux -S -o - -emit-llvm %s | FileCheck %s
+// RUN: %clang -target mips64-unknown-linux -S -o - -emit-llvm %s | FileCheck %s
+// RUN: %clang -target mips64el-unknown-linux -S -o - -emit-llvm %s | FileCheck %s
+
+int foo (int a, ...)
+{
+    __builtin_va_list va;
+
+    __builtin_va_start (va, a);
+
+    int n = __builtin_va_arg (va, int);
+    // CHECK: = va_arg i8** %va, i32
+    
+    __builtin_va_end (va);
+
+    return n;
+}
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D4742.12067.patch
Type: text/x-patch
Size: 2583 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20140731/3b451ed5/attachment.bin>