[PowerPC] Fix calculating address of arguments on stack for variadic func

Fix calculating address of arguments larger than 32 bit on stack for
variadic functions (rounding up address to alignment) on ppc32 architecture.

Patch by Strahinja Petrovic.

Differential Revision: http://reviews.llvm.org/D14871

llvm-svn: 254670

1 files changed, 34 insertions, 28 deletions

diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index fe98854897e..da262c1087c 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -162,6 +162,23 @@ void ABIArgInfo::dump() const {
   OS << ")\n";
 }
 
+// Dynamically round a pointer up to a multiple of the given alignment.
+static llvm::Value *emitRoundPointerUpToAlignment(CodeGenFunction &CGF,
+                                                  llvm::Value *Ptr,
+                                                  CharUnits Align) {
+  llvm::Value *PtrAsInt = Ptr;
+  // OverflowArgArea = (OverflowArgArea + Align - 1) & -Align;
+  PtrAsInt = CGF.Builder.CreatePtrToInt(PtrAsInt, CGF.IntPtrTy);
+  PtrAsInt = CGF.Builder.CreateAdd(PtrAsInt,
+        llvm::ConstantInt::get(CGF.IntPtrTy, Align.getQuantity() - 1));
+  PtrAsInt = CGF.Builder.CreateAnd(PtrAsInt,
+           llvm::ConstantInt::get(CGF.IntPtrTy, -Align.getQuantity()));
+  PtrAsInt = CGF.Builder.CreateIntToPtr(PtrAsInt,
+                                        Ptr->getType(),
+                                        Ptr->getName() + ".aligned");
+  return PtrAsInt;
+}
+
 /// Emit va_arg for a platform using the common void* representation,
 /// where arguments are simply emitted in an array of slots on the stack.
 ///
@@ -193,17 +210,10 @@ static Address emitVoidPtrDirectVAArg(CodeGenFunction &CGF,
   // If the CC aligns values higher than the slot size, do so if needed.
   Address Addr = Address::invalid();
   if (AllowHigherAlign && DirectAlign > SlotSize) {
-    llvm::Value *PtrAsInt = Ptr;
-    PtrAsInt = CGF.Builder.CreatePtrToInt(PtrAsInt, CGF.IntPtrTy);
-    PtrAsInt = CGF.Builder.CreateAdd(PtrAsInt,
-          llvm::ConstantInt::get(CGF.IntPtrTy, DirectAlign.getQuantity() - 1));
-    PtrAsInt = CGF.Builder.CreateAnd(PtrAsInt,
-             llvm::ConstantInt::get(CGF.IntPtrTy, -DirectAlign.getQuantity()));
-    Addr = Address(CGF.Builder.CreateIntToPtr(PtrAsInt, Ptr->getType(),
-                                              "argp.cur.aligned"),
-                   DirectAlign);
+    Addr = Address(emitRoundPointerUpToAlignment(CGF, Ptr, DirectAlign),
+                                                 DirectAlign);
   } else {
-    Addr = Address(Ptr, SlotSize);
+    Addr = Address(Ptr, SlotSize); 
   }
 
   // Advance the pointer past the argument, then store that back.
@@ -3072,19 +3082,10 @@ static Address EmitX86_64VAArgFromMemory(CodeGenFunction &CGF,
   // byte boundary if alignment needed by type exceeds 8 byte boundary.
   // It isn't stated explicitly in the standard, but in practice we use
   // alignment greater than 16 where necessary.
-  uint64_t Align = CGF.getContext().getTypeAlignInChars(Ty).getQuantity();
-  if (Align > 8) {
-    // overflow_arg_area = (overflow_arg_area + align - 1) & -align;
-    llvm::Value *Offset =
-      llvm::ConstantInt::get(CGF.Int64Ty, Align - 1);
-    overflow_arg_area = CGF.Builder.CreateGEP(overflow_arg_area, Offset);
-    llvm::Value *AsInt = CGF.Builder.CreatePtrToInt(overflow_arg_area,
-                                                    CGF.Int64Ty);
-    llvm::Value *Mask = llvm::ConstantInt::get(CGF.Int64Ty, -(uint64_t)Align);
-    overflow_arg_area =
-      CGF.Builder.CreateIntToPtr(CGF.Builder.CreateAnd(AsInt, Mask),
-                                 overflow_arg_area->getType(),
-                                 "overflow_arg_area.align");
+  CharUnits Align = CGF.getContext().getTypeAlignInChars(Ty);
+  if (Align > CharUnits::fromQuantity(8)) {
+    overflow_arg_area = emitRoundPointerUpToAlignment(CGF, overflow_arg_area,
+                                                      Align);
   }
 
   // AMD64-ABI 3.5.7p5: Step 8. Fetch type from l->overflow_arg_area.
@@ -3106,7 +3107,7 @@ static Address EmitX86_64VAArgFromMemory(CodeGenFunction &CGF,
   CGF.Builder.CreateStore(overflow_arg_area, overflow_arg_area_p);
 
   // AMD64-ABI 3.5.7p5: Step 11. Return the fetched type.
-  return Address(Res, CharUnits::fromQuantity(Align));
+  return Address(Res, Align);
 }
 
 Address X86_64ABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAListAddr,
@@ -3541,11 +3542,16 @@ Address PPC32_SVR4_ABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAList,
 
     Address OverflowAreaAddr =
       Builder.CreateStructGEP(VAList, 3, CharUnits::fromQuantity(4));
-    Address OverflowArea(Builder.CreateLoad(OverflowAreaAddr),
+    Address OverflowArea(Builder.CreateLoad(OverflowAreaAddr, "argp.cur"),
                          OverflowAreaAlign);
-
-    // The current address is the address of the varargs element.
-    // FIXME: do we not need to round up to alignment?
+    // Round up address of argument to alignment
+    CharUnits Align = CGF.getContext().getTypeAlignInChars(Ty);
+    if (Align > OverflowAreaAlign) {
+      llvm::Value *Ptr = OverflowArea.getPointer();
+      OverflowArea = Address(emitRoundPointerUpToAlignment(CGF, Ptr, Align),
+                                                           Align);
+    }
+ 
     MemAddr = Builder.CreateElementBitCast(OverflowArea, DirectTy);
 
     // Increase the overflow area.