Handle branch relative to pc in ARM integrated assembler.

src/IceAssemblerARM32.h

 //===- subzero/src/IceAssemblerARM32.h - Assembler for ARM32 ----*- C++ -*-===//
 //
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 //
 // Modified by the Subzero authors.
 //
 //===----------------------------------------------------------------------===//
 //
@@ skipping 20 matching lines @@
 #include "IceConditionCodesARM32.h"
 #include "IceDefs.h"
 #include "IceFixups.h"
 #include "IceInstARM32.h"
 #include "IceRegistersARM32.h"
 #include "IceTargetLowering.h"
 
 namespace Ice {
 namespace ARM32 {
 
+/// Encoding of an ARM 32-bit instruction.
+using InstValueType = uint32_t;

[Jim Stichnoth, 2015/10/23 21:32:07]

You might consider shortening these to InstValueT and InstOffsetT, analogous to
Ice::SizeT.  Even shorter possibilities might be IValueT/IOffsetT or
ValueT/OffsetT.

[Karl, 2015/10/26 18:32:43]

ValueT appeared too easy to confuse with other possibilities. Used IValueT and
IOffsetT.

+
+/// An Offset value (+/-) used in an ARM 32-bit instruction.
+using InstOffsetType = int32_t;
+
 class AssemblerARM32 : public Assembler {
   AssemblerARM32() = delete;
   AssemblerARM32(const AssemblerARM32 &) = delete;
   AssemblerARM32 &operator=(const AssemblerARM32 &) = delete;
 
 public:
   explicit AssemblerARM32(GlobalContext *Ctx, bool use_far_branches = false)
       : Assembler(Asm_ARM32, Ctx) {
     // TODO(kschimpf): Add mode if needed when branches are handled.
     (void)use_far_branches;
   }
   ~AssemblerARM32() override {
     if (BuildDefs::asserts()) {
       for (const Label *Label : CfgNodeLabels) {
         Label->finalCheck();
       }
       for (const Label *Label : LocalLabels) {
         Label->finalCheck();
       }
     }
   }
 
   void alignFunction() override {
     const SizeT Align = 1 << getBundleAlignLog2Bytes();
     SizeT BytesNeeded = Utils::OffsetToAlignment(Buffer.getPosition(), Align);
-    constexpr uint32_t UndefinedInst = 0xe7fedef0; // udf #60896
-    constexpr SizeT InstSize = sizeof(int32_t);
+    constexpr InstValueType UndefinedInst = 0xe7fedef0; // udf #60896
+    constexpr SizeT InstSize = sizeof(InstValueType);
     assert(BytesNeeded % InstSize == 0);
     while (BytesNeeded > 0) {
       AssemblerBuffer::EnsureCapacity ensured(&Buffer);
       emitInst(UndefinedInst);
       BytesNeeded -= InstSize;
     }
   }
 
   SizeT getBundleAlignLog2Bytes() const override { return 4; }
 
   const char *getAlignDirective() const override { return ".p2alignl"; }
 
   llvm::ArrayRef<uint8_t> getNonExecBundlePadding() const override {
     // Use a particular UDF encoding -- TRAPNaCl in LLVM: 0xE7FEDEF0
     // http://llvm.org/viewvc/llvm-project?view=revision&revision=173943
     static const uint8_t Padding[] = {0xE7, 0xFE, 0xDE, 0xF0};
     return llvm::ArrayRef<uint8_t>(Padding, 4);
   }
 
   void padWithNop(intptr_t Padding) override {
     (void)Padding;
     llvm_unreachable("Not yet implemented.");
   }
 
   Ice::Label *getCfgNodeLabel(SizeT NodeNumber) override {
     assert(NodeNumber < CfgNodeLabels.size());
     return CfgNodeLabels[NodeNumber];
   }
 
-  void bindCfgNodeLabel(const CfgNode *Node) override;
+  Label *getOrCreateCfgNodeLabel(SizeT NodeNumber) {
+    return getOrCreateLabel(NodeNumber, CfgNodeLabels);
+  }
+
+  Label *getOrCreateLocalLabel(SizeT Number) {
+    return getOrCreateLabel(Number, LocalLabels);
+  }
 
   void bindLocalLabel(SizeT Number) {
     Label *L = getOrCreateLocalLabel(Number);
     if (!getPreliminary())
       this->bind(L);
   }
 
   bool fixupIsPCRel(FixupKind Kind) const override {
     (void)Kind;
     // TODO(kschimpf) Decide if we need this.
     return false;
   }
 
   void bind(Label *label);
 
   // List of instructions implemented by integrated assembler.
 
   void add(const Operand *OpRd, const Operand *OpRn, const Operand *OpSrc1,
            bool SetFlags, CondARM32::Cond Cond);
 
+  void b(Label *L, CondARM32::Cond Cond);
+
   void bkpt(uint16_t Imm16);
 
   void ldr(const Operand *OpRt, const Operand *OpAddress, CondARM32::Cond Cond);
 
   void mov(const Operand *OpRd, const Operand *OpSrc, CondARM32::Cond Cond);
 
   void bx(RegARM32::GPRRegister Rm, CondARM32::Cond Cond = CondARM32::AL);
 
   void str(const Operand *OpRt, const Operand *OpAddress, CondARM32::Cond Cond);
 
   void sub(const Operand *OpRd, const Operand *OpRn, const Operand *OpSrc1,
            bool SetFlags, CondARM32::Cond Cond);
 
   static bool classof(const Assembler *Asm) {
     return Asm->getKind() == Asm_ARM32;
   }
 
-  void emitTextInst(const std::string &Text, SizeT InstSize = sizeof(uint32_t));
+  void emitTextInst(const std::string &Text,
+                    SizeT InstSize = sizeof(InstValueType));
 
 private:
   // A vector of pool-allocated x86 labels for CFG nodes.
   using LabelVector = std::vector<Label *>;
   LabelVector CfgNodeLabels;
   // A vector of pool-allocated x86 labels for Local labels.
   LabelVector LocalLabels;
 
   Label *getOrCreateLabel(SizeT Number, LabelVector &Labels);
-  Label *getOrCreateCfgNodeLabel(SizeT NodeNumber) {
-    return getOrCreateLabel(NodeNumber, CfgNodeLabels);
-  }
-  Label *getOrCreateLocalLabel(SizeT Number) {
-    return getOrCreateLabel(Number, LocalLabels);
-  }
 
-  void emitInst(uint32_t Value) { Buffer.emit<uint32_t>(Value); }
+  void bindCfgNodeLabel(const CfgNode *Node) override;
+
+  void emitInst(InstValueType Value) { Buffer.emit<InstValueType>(Value); }
 
   // Pattern cccctttoooosnnnnddddiiiiiiiiiiii where cccc=Cond, ttt=Type,
   // oooo=Opcode, nnnn=Rn, dddd=Rd, iiiiiiiiiiii=imm12 (See ARM section A5.2.3).
-  void emitType01(CondARM32::Cond Cond, uint32_t Type, uint32_t Opcode,
-                  bool SetCc, uint32_t Rn, uint32_t Rd, uint32_t imm12);
+  void emitType01(CondARM32::Cond Cond, InstValueType Type,
+                  InstValueType Opcode, bool SetCc, InstValueType Rn,
+                  InstValueType Rd, InstValueType imm12);
+
+  void emitType05(CondARM32::Cond COnd, int32_t Offset, bool Link);
 
   // Pattern ccccoooaabalnnnnttttaaaaaaaaaaaa where cccc=Cond, ooo=InstType,
   // l=isLoad, b=isByte, and aaa0a0aaaa0000aaaaaaaaaaaa=Address. Note that
   // Address is assumed to be defined by decodeAddress() in
   // IceAssemblerARM32.cpp.
-  void emitMemOp(CondARM32::Cond Cond, uint32_t InstType, bool IsLoad,
+  void emitMemOp(CondARM32::Cond Cond, InstValueType InstType, bool IsLoad,
                  bool IsByte, uint32_t Rt, uint32_t Address);
+
+  void emitBranch(Label *L, CondARM32::Cond, bool Link);
+
+  // Encodes The given Offset into the branch instruction Inst.
+  InstValueType encodeBranchOffset(InstOffsetType Offset, InstValueType Inst);
+
+  // Returns the offset encoded in the branch instruction Inst.
+  static InstOffsetType decodeBranchOffset(InstValueType Inst);
 };
 
 } // end of namespace ARM32
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEASSEMBLERARM32_H