From 96b6682d2d65f94c262590ef88bafdc70171ab8c Mon Sep 17 00:00:00 2001
From: Alexey Frunze <Alexey.Frunze@imgtec.com>
Date: Sat, 10 Sep 2016 02:32:44 -0700
Subject: MIPS32: Implement table-based packed switch

Test: booted MIPS32R2 in QEMU
Test: test-art-target-run-test-optimizing (MIPS32R2) on CI20
Test: booted MIPS64 (with 2nd arch MIPS32R6) in QEMU
Test: test-art-target-run-test-optimizing (MIPS32R6) in QEMU
Test: test-art-host-gtest

Change-Id: I2e1a65ff1ba9406b84351ba7998f853b1ce4aef9
---
 compiler/utils/mips/assembler_mips.h | 65 ++++++++++++++++++++++++++++++++++--
 1 file changed, 62 insertions(+), 3 deletions(-)

(limited to 'compiler/utils/mips/assembler_mips.h')

diff --git a/compiler/utils/mips/assembler_mips.h b/compiler/utils/mips/assembler_mips.h
index d50c439418..099620ccb8 100644
--- a/compiler/utils/mips/assembler_mips.h
+++ b/compiler/utils/mips/assembler_mips.h
@@ -126,6 +126,36 @@ class Literal {
   DISALLOW_COPY_AND_ASSIGN(Literal);
 };
 
+// Jump table: table of labels emitted after the literals. Similar to literals.
+class JumpTable {
+ public:
+  explicit JumpTable(std::vector<MipsLabel*>&& labels)
+      : label_(), labels_(std::move(labels)) {
+  }
+
+  uint32_t GetSize() const {
+    return static_cast<uint32_t>(labels_.size()) * sizeof(uint32_t);
+  }
+
+  const std::vector<MipsLabel*>& GetData() const {
+    return labels_;
+  }
+
+  MipsLabel* GetLabel() {
+    return &label_;
+  }
+
+  const MipsLabel* GetLabel() const {
+    return &label_;
+  }
+
+ private:
+  MipsLabel label_;
+  std::vector<MipsLabel*> labels_;
+
+  DISALLOW_COPY_AND_ASSIGN(JumpTable);
+};
+
 // Slowpath entered when Thread::Current()->_exception is non-null.
 class MipsExceptionSlowPath {
  public:
@@ -158,6 +188,7 @@ class MipsAssembler FINAL : public Assembler, public JNIMacroAssembler<PointerSi
         ds_fsm_state_(kExpectingLabel),
         ds_fsm_target_pc_(0),
         literals_(arena->Adapter(kArenaAllocAssembler)),
+        jump_tables_(arena->Adapter(kArenaAllocAssembler)),
         last_position_adjustment_(0),
         last_old_position_(0),
         last_branch_id_(0),
@@ -685,6 +716,11 @@ class MipsAssembler FINAL : public Assembler, public JNIMacroAssembler<PointerSi
     return NewLiteral(sizeof(value), reinterpret_cast<const uint8_t*>(&value));
   }
 
+  // Load label address using the base register (for R2 only) or using PC-relative loads
+  // (for R6 only; base_reg must be ZERO). To be used with data labels in the literal /
+  // jump table area only and not with regular code labels.
+  void LoadLabelAddress(Register dest_reg, Register base_reg, MipsLabel* label);
+
   // Create a new literal with the given data.
   Literal* NewLiteral(size_t size, const uint8_t* data);
 
@@ -692,6 +728,12 @@ class MipsAssembler FINAL : public Assembler, public JNIMacroAssembler<PointerSi
   // (for R6 only; base_reg must be ZERO).
   void LoadLiteral(Register dest_reg, Register base_reg, Literal* literal);
 
+  // Create a jump table for the given labels that will be emitted when finalizing.
+  // When the table is emitted, offsets will be relative to the location of the table.
+  // The table location is determined by the location of its label (the label precedes
+  // the table data) and should be loaded using LoadLabelAddress().
+  JumpTable* CreateJumpTable(std::vector<MipsLabel*>&& labels);
+
   //
   // Overridden common assembler high-level functionality.
   //
@@ -935,24 +977,32 @@ class MipsAssembler FINAL : public Assembler, public JNIMacroAssembler<PointerSi
       kUncondBranch,
       kCondBranch,
       kCall,
+      // R2 near label.
+      kLabel,
       // R2 near literal.
       kLiteral,
       // R2 long branches.
       kLongUncondBranch,
       kLongCondBranch,
       kLongCall,
+      // R2 far label.
+      kFarLabel,
       // R2 far literal.
       kFarLiteral,
       // R6 short branches.
       kR6UncondBranch,
       kR6CondBranch,
       kR6Call,
+      // R6 near label.
+      kR6Label,
       // R6 near literal.
       kR6Literal,
       // R6 long branches.
       kR6LongUncondBranch,
       kR6LongCondBranch,
       kR6LongCall,
+      // R6 far label.
+      kR6FarLabel,
       // R6 far literal.
       kR6FarLiteral,
     };
@@ -1009,8 +1059,12 @@ class MipsAssembler FINAL : public Assembler, public JNIMacroAssembler<PointerSi
            BranchCondition condition,
            Register lhs_reg,
            Register rhs_reg);
-    // Literal.
-    Branch(bool is_r6, uint32_t location, Register dest_reg, Register base_reg);
+    // Label address (in literal area) or literal.
+    Branch(bool is_r6,
+           uint32_t location,
+           Register dest_reg,
+           Register base_reg,
+           Type label_or_literal_type);
 
     // Some conditional branches with lhs = rhs are effectively NOPs, while some
     // others are effectively unconditional. MIPSR6 conditional branches require lhs != rhs.
@@ -1105,7 +1159,7 @@ class MipsAssembler FINAL : public Assembler, public JNIMacroAssembler<PointerSi
 
    private:
     // Completes branch construction by determining and recording its type.
-    void InitializeType(bool is_call, bool is_literal, bool is_r6);
+    void InitializeType(Type initial_type, bool is_r6);
     // Helper for the above.
     void InitShortOrLong(OffsetBits ofs_size, Type short_type, Type long_type);
 
@@ -1178,6 +1232,8 @@ class MipsAssembler FINAL : public Assembler, public JNIMacroAssembler<PointerSi
   uint32_t GetBranchOrPcRelBaseForEncoding(const MipsAssembler::Branch* branch) const;
 
   void EmitLiterals();
+  void ReserveJumpTableSpace();
+  void EmitJumpTables();
   void PromoteBranches();
   void EmitBranch(Branch* branch);
   void EmitBranches();
@@ -1227,6 +1283,9 @@ class MipsAssembler FINAL : public Assembler, public JNIMacroAssembler<PointerSi
   // without invalidating pointers and references to existing elements.
   ArenaDeque<Literal> literals_;
 
+  // Jump table list.
+  ArenaDeque<JumpTable> jump_tables_;
+
   // There's no PC-relative addressing on MIPS32R2. So, in order to access literals relative to PC
   // we get PC using the NAL instruction. This label marks the position within the assembler buffer
   // that PC (from NAL) points to.
-- 
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