GlobalISel: translate @llvm.va_start intrinsic.

Because we need to preserve the memory access being performed we need a
separate instruction to represent this.

llvm-svn: 294492

llvm/include/llvm/Target/GenericOpcodes.td

@@ -91,6 +91,13 @@ def G_FCONSTANT : Instruction {
   let hasSideEffects = 0;
 }
 
+def G_VASTART : Instruction {
+  let OutOperandList = (outs);
+  let InOperandList = (ins type0:$list);
+  let hasSideEffects = 0;
+  let mayStore = 1;
+}
+
 //------------------------------------------------------------------------------
 // Binary ops.
 //------------------------------------------------------------------------------

llvm/include/llvm/Target/TargetLowering.h

@@ -987,6 +987,11 @@ public:
     return GatherAllAliasesMaxDepth;
   }
 
+  /// Returns the size of the platform's va_list object.
+  virtual unsigned getVaListSizeInBits(const DataLayout &DL) const {
+    return getPointerTy(DL).getSizeInBits();
+  }
+
   /// \brief Get maximum # of store operations permitted for llvm.memset
   ///
   /// This function returns the maximum number of store operations permitted

llvm/include/llvm/Target/TargetOpcodes.def

@@ -280,6 +280,9 @@ HANDLE_TARGET_OPCODE(G_CONSTANT)
 /// Generic floating constant.
 HANDLE_TARGET_OPCODE(G_FCONSTANT)
 
+/// Generic va_start instruction. Stores to its one pointer operand.
+HANDLE_TARGET_OPCODE(G_VASTART)
+
 // Generic sign extend
 HANDLE_TARGET_OPCODE(G_SEXT)
 

llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp

@@ -583,6 +583,17 @@ bool IRTranslator::translateKnownIntrinsic(const CallInst &CI, Intrinsic::ID ID,
     // No target I know of cares about va_end. Certainly no in-tree target
     // does. Simplest intrinsic ever!
     return true;
+  case Intrinsic::vastart: {
+    auto &TLI = *MF->getSubtarget().getTargetLowering();
+    Value *Ptr = CI.getArgOperand(0);
+    unsigned ListSize = TLI.getVaListSizeInBits(*DL) / 8;
+
+    MIRBuilder.buildInstr(TargetOpcode::G_VASTART)
+        .addUse(getOrCreateVReg(*Ptr))
+        .addMemOperand(MF->getMachineMemOperand(
+            MachinePointerInfo(Ptr), MachineMemOperand::MOStore, ListSize, 0));
+    return true;
+  }
   case Intrinsic::dbg_value: {
     // This form of DBG_VALUE is target-independent.
     const DbgValueInst &DI = cast<DbgValueInst>(CI);

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

@@ -10702,3 +10702,11 @@ bool AArch64TargetLowering::isIntDivCheap(EVT VT, AttributeSet Attr) const {
       Attr.hasAttribute(AttributeSet::FunctionIndex, Attribute::MinSize);
   return OptSize && !VT.isVector();
 }
+
+unsigned
+AArch64TargetLowering::getVaListSizeInBits(const DataLayout &DL) const {
+  if (Subtarget->isTargetDarwin())
+    return getPointerTy(DL).getSizeInBits();
+
+  return 3 * getPointerTy(DL).getSizeInBits() + 2 * 32;
+}

llvm/lib/Target/AArch64/AArch64ISelLowering.h

@@ -435,6 +435,9 @@ public:
     return true;
   }
 
+  /// Returns the size of the platform's va_list object.
+  unsigned getVaListSizeInBits(const DataLayout &DL) const override;
+
 private:
   bool isExtFreeImpl(const Instruction *Ext) const override;
 

llvm/test/CodeGen/AArch64/GlobalISel/vastart.ll

@@ -0,0 +1,13 @@
+; RUN: llc -O0 -stop-after=irtranslator -global-isel -verify-machineinstrs %s -o -  -mtriple=aarch64-apple-ios7.0 | FileCheck --check-prefix=CHECK --check-prefix=CHECK-IOS %s
+; RUN: llc -O0 -stop-after=irtranslator -global-isel -verify-machineinstrs %s -o -  -mtriple=aarch64-linux-gnu | FileCheck --check-prefix=CHECK --check-prefix=CHECK-LINUX %s
+
+
+declare void @llvm.va_start(i8*)
+define void @test_va_start(i8* %list) {
+; CHECK-LABEL: name: test_va_start
+; CHECK: [[LIST:%[0-9]+]](p0) = COPY %x0
+; CHECK-IOS: G_VASTART [[LIST]](p0) :: (store 8 into %ir.list, align 0)
+; CHECK-LINUX: G_VASTART [[LIST]](p0) :: (store 32 into %ir.list, align 0)
+  call void @llvm.va_start(i8* %list)
+  ret void
+}