Bug 1271968 - IonMonkey: MIPS: Replace long jumps by mixed jumps.

Tag: #1542

4 files changed, 55 insertions, 132 deletions

diff --git a/js/src/jit/mips32/Assembler-mips32.cpp b/js/src/jit/mips32/Assembler-mips32.cpp
index 1b86e9d32..461f8d813 100644
--- a/js/src/jit/mips32/Assembler-mips32.cpp
+++ b/js/src/jit/mips32/Assembler-mips32.cpp
@@ -120,8 +120,11 @@ js::jit::SA(FloatRegister r)
 void
 jit::PatchJump(CodeLocationJump& jump_, CodeLocationLabel label, ReprotectCode reprotect)
 {
-    Instruction* inst1 = (Instruction*)jump_.raw();
-    Instruction* inst2 = inst1->next();
+    Instruction* inst1;
+    Instruction* inst2;
+
+    inst1 = AssemblerMIPSShared::GetInstructionImmediateFromJump((Instruction*)jump_.raw());
+    inst2 = inst1->next();
 
     MaybeAutoWritableJitCode awjc(inst1, 8, reprotect);
     AssemblerMIPSShared::UpdateLuiOriValue(inst1, inst2, (uint32_t)label.raw());
@@ -157,23 +160,6 @@ jit::PatchBackedge(CodeLocationJump& jump, CodeLocationLabel label,
     }
 }
 
-void
-Assembler::executableCopy(uint8_t* buffer)
-{
-    MOZ_ASSERT(isFinished);
-    m_buffer.executableCopy(buffer);
-
-    // Patch all long jumps during code copy.
-    for (size_t i = 0; i < longJumps_.length(); i++) {
-        Instruction* inst1 = (Instruction*) ((uint32_t)buffer + longJumps_[i]);
-
-        uint32_t value = Assembler::ExtractLuiOriValue(inst1, inst1->next());
-        AssemblerMIPSShared::UpdateLuiOriValue(inst1, inst1->next(), (uint32_t)buffer + value);
-    }
-
-    AutoFlushICache::setRange(uintptr_t(buffer), m_buffer.size());
-}
-
 uintptr_t
 Assembler::GetPointer(uint8_t* instPtr)
 {
@@ -314,8 +300,12 @@ void
 Assembler::bind(InstImm* inst, uintptr_t branch, uintptr_t target)
 {
     int32_t offset = target - branch;
-    InstImm inst_bgezal = InstImm(op_regimm, zero, rt_bgezal, BOffImm16(0));
-    InstImm inst_beq = InstImm(op_beq, zero, zero, BOffImm16(0));
+
+    // Generate the patchable mixed jump for call.
+    if (inst->extractOpcode() == ((uint32_t)op_jal >> OpcodeShift)) {
+        addMixedJump(BufferOffset(branch), ImmPtr((void*)target));
+        return;
+    }
 
     // If encoded offset is 4, then the jump must be short
     if (BOffImm16(inst[0]).decode() == 4) {
@@ -325,46 +315,13 @@ Assembler::bind(InstImm* inst, uintptr_t branch, uintptr_t target)
         return;
     }
 
-    // Generate the long jump for calls because return address has to be the
-    // address after the reserved block.
-    if (inst[0].encode() == inst_bgezal.encode()) {
-        addLongJump(BufferOffset(branch));
-        Assembler::WriteLuiOriInstructions(inst, &inst[1], ScratchRegister, target);
-        inst[2] = InstReg(op_special, ScratchRegister, zero, ra, ff_jalr).encode();
-        // There is 1 nop after this.
-        return;
-    }
-
     if (BOffImm16::IsInRange(offset)) {
-        bool conditional = (inst[0].encode() != inst_bgezal.encode() &&
-                            inst[0].encode() != inst_beq.encode());
-
         inst[0].setBOffImm16(BOffImm16(offset));
         inst[1].makeNop();
-
-        // Skip the trailing nops in conditional branches.
-        if (conditional) {
-            inst[2] = InstImm(op_regimm, zero, rt_bgez, BOffImm16(3 * sizeof(void*))).encode();
-            // There are 2 nops after this
-        }
         return;
     }
 
-    if (inst[0].encode() == inst_beq.encode()) {
-        // Handle long unconditional jump.
-        addLongJump(BufferOffset(branch));
-        Assembler::WriteLuiOriInstructions(inst, &inst[1], ScratchRegister, target);
-        inst[2] = InstReg(op_special, ScratchRegister, zero, zero, ff_jr).encode();
-        // There is 1 nop after this.
-    } else {
-        // Handle long conditional jump.
-        inst[0] = invertBranch(inst[0], BOffImm16(5 * sizeof(void*)));
-        // No need for a "nop" here because we can clobber scratch.
-        addLongJump(BufferOffset(branch + sizeof(void*)));
-        Assembler::WriteLuiOriInstructions(&inst[1], &inst[2], ScratchRegister, target);
-        inst[3] = InstReg(op_special, ScratchRegister, zero, zero, ff_jr).encode();
-        // There is 1 nop after this.
-    }
+    addMixedJump(BufferOffset(branch), ImmPtr((const void*)target));
 }
 
 void
@@ -379,19 +336,16 @@ Assembler::bind(RepatchLabel* label)
         InstImm inst_beq = InstImm(op_beq, zero, zero, BOffImm16(0));
         uint32_t offset = dest.getOffset() - label->offset();
 
-        // If first instruction is lui, then this is a long jump.
+        // If first instruction is j, then this is a mixed jump.
         // If second instruction is lui, then this is a loop backedge.
-        if (inst[0].extractOpcode() == (uint32_t(op_lui) >> OpcodeShift)) {
-            // For unconditional long branches generated by ma_liPatchable,
-            // such as under:
-            //     jumpWithpatch
-            AssemblerMIPSShared::UpdateLuiOriValue(inst, inst->next(), dest.getOffset());
+        if (inst[0].extractOpcode() == (uint32_t(op_j) >> OpcodeShift)) {
+            // For unconditional long branches generated by jumpWithPatch
+            addMixedJump(b, ImmPtr((void*)dest.getOffset()), MixedJumpPatch::PATCHABLE);
         } else if (inst[1].extractOpcode() == (uint32_t(op_lui) >> OpcodeShift) ||
                    BOffImm16::IsInRange(offset))
         {
             // Handle code produced by:
             //     backedgeJump
-            //     branchWithCode
             MOZ_ASSERT(BOffImm16::IsInRange(offset));
             MOZ_ASSERT(inst[0].extractOpcode() == (uint32_t(op_beq) >> OpcodeShift) ||
                        inst[0].extractOpcode() == (uint32_t(op_bne) >> OpcodeShift) ||
@@ -399,30 +353,25 @@ Assembler::bind(RepatchLabel* label)
                        inst[0].extractOpcode() == (uint32_t(op_bgtz) >> OpcodeShift));
             inst[0].setBOffImm16(BOffImm16(offset));
         } else if (inst[0].encode() == inst_beq.encode()) {
-            // Handle open long unconditional jumps created by
+            // Handle open mixed unconditional jumps created by
             // MacroAssemblerMIPSShared::ma_b(..., wasm::Trap, ...).
-            // We need to add it to long jumps array here.
+            // We need to add it to mixed jumps array here.
             // See MacroAssemblerMIPS::branchWithCode().
             MOZ_ASSERT(inst[1].encode() == NopInst);
-            MOZ_ASSERT(inst[2].encode() == NopInst);
-            MOZ_ASSERT(inst[3].encode() == NopInst);
-            addLongJump(BufferOffset(label->offset()));
-            Assembler::WriteLuiOriInstructions(inst, &inst[1], ScratchRegister, dest.getOffset());
-            inst[2] = InstReg(op_special, ScratchRegister, zero, zero, ff_jr).encode();
+            addMixedJump(b, ImmPtr((void*)dest.getOffset()), MixedJumpPatch::PATCHABLE);
+            inst[0] = InstJump(op_j, JOffImm26(0)).encode();
         } else {
-            // Handle open long conditional jumps created by
+            // Handle open mixed conditional jumps created by
             // MacroAssemblerMIPSShared::ma_b(..., wasm::Trap, ...).
-            inst[0] = invertBranch(inst[0], BOffImm16(5 * sizeof(void*)));
+            inst[0] = invertBranch(inst[0], BOffImm16(4 * sizeof(void*)));
             // No need for a "nop" here because we can clobber scratch.
-            // We need to add it to long jumps array here.
+            // We need to add it to mixed jumps array here.
             // See MacroAssemblerMIPS::branchWithCode().
             MOZ_ASSERT(inst[1].encode() == NopInst);
             MOZ_ASSERT(inst[2].encode() == NopInst);
             MOZ_ASSERT(inst[3].encode() == NopInst);
-            MOZ_ASSERT(inst[4].encode() == NopInst);
-            addLongJump(BufferOffset(label->offset() + sizeof(void*)));
-            Assembler::WriteLuiOriInstructions(&inst[1], &inst[2], ScratchRegister, dest.getOffset());
-            inst[3] = InstReg(op_special, ScratchRegister, zero, zero, ff_jr).encode();
+            addMixedJump(b, ImmPtr((void*)dest.getOffset()), MixedJumpPatch::PATCHABLE);
+            inst[2] = InstJump(op_j, JOffImm26(0)).encode();
         }
     }
     label->bind(dest.getOffset());
diff --git a/js/src/jit/mips32/Assembler-mips32.h b/js/src/jit/mips32/Assembler-mips32.h
index cf7f0d228..a519b9876 100644
--- a/js/src/jit/mips32/Assembler-mips32.h
+++ b/js/src/jit/mips32/Assembler-mips32.h
@@ -154,10 +154,6 @@ class Assembler : public AssemblerMIPSShared
 
     void bind(InstImm* inst, uintptr_t branch, uintptr_t target);
 
-    // Copy the assembly code to the given buffer, and perform any pending
-    // relocations relying on the target address.
-    void executableCopy(uint8_t* buffer);
-
     static uint32_t PatchWrite_NearCallSize();
 
     static uint32_t ExtractLuiOriValue(Instruction* inst0, Instruction* inst1);
diff --git a/js/src/jit/mips32/MacroAssembler-mips32.cpp b/js/src/jit/mips32/MacroAssembler-mips32.cpp
index d3d3a75d1..53d1a7925 100644
--- a/js/src/jit/mips32/MacroAssembler-mips32.cpp
+++ b/js/src/jit/mips32/MacroAssembler-mips32.cpp
@@ -504,16 +504,13 @@ MacroAssemblerMIPS::ma_b(Address addr, ImmGCPtr imm, Label* label, Condition c,
 }
 
 void
-MacroAssemblerMIPS::ma_bal(Label* label, DelaySlotFill delaySlotFill)
+MacroAssemblerMIPS::ma_jal(Label* label)
 {
     if (label->bound()) {
-        // Generate the long jump for calls because return address has to be
-        // the address after the reserved block.
-        addLongJump(nextOffset());
-        ma_liPatchable(ScratchRegister, Imm32(label->offset()));
-        as_jalr(ScratchRegister);
-        if (delaySlotFill == FillDelaySlot)
-            as_nop();
+        // Generate the mixed jump.
+        addMixedJump(nextOffset(), ImmPtr((void*)label->offset()));
+        as_jal(JOffImm26(0));
+        as_nop();
         return;
     }
 
@@ -521,16 +518,12 @@ MacroAssemblerMIPS::ma_bal(Label* label, DelaySlotFill delaySlotFill)
     uint32_t nextInChain = label->used() ? label->offset() : LabelBase::INVALID_OFFSET;
 
     // Make the whole branch continous in the buffer.
-    m_buffer.ensureSpace(4 * sizeof(uint32_t));
+    m_buffer.ensureSpace(2 * sizeof(uint32_t));
 
-    BufferOffset bo = writeInst(getBranchCode(BranchIsCall).encode());
+    BufferOffset bo = as_jal(JOffImm26(0));
     writeInst(nextInChain);
     if (!oom())
         label->use(bo.getOffset());
-    // Leave space for long jump.
-    as_nop();
-    if (delaySlotFill == FillDelaySlot)
-        as_nop();
 }
 
 void
@@ -554,20 +547,18 @@ MacroAssemblerMIPS::branchWithCode(InstImm code, Label* label, JumpKind jumpKind
         }
 
         if (code.encode() == inst_beq.encode()) {
-            // Handle long jump
-            addLongJump(nextOffset());
-            ma_liPatchable(ScratchRegister, Imm32(label->offset()));
-            as_jr(ScratchRegister);
+            // Handle mixed jump
+            addMixedJump(nextOffset(), ImmPtr((void*)label->offset()));
+            as_j(JOffImm26(0));
             as_nop();
             return;
         }
 
         // Handle long conditional branch
-        writeInst(invertBranch(code, BOffImm16(5 * sizeof(uint32_t))).encode());
-        // No need for a "nop" here because we can clobber scratch.
-        addLongJump(nextOffset());
-        ma_liPatchable(ScratchRegister, Imm32(label->offset()));
-        as_jr(ScratchRegister);
+        writeInst(invertBranch(code, BOffImm16(4 * sizeof(uint32_t))).encode());
+        as_nop();
+        addMixedJump(nextOffset(), ImmPtr((void*)label->offset()));
+        as_j(JOffImm26(0));
         as_nop();
         return;
     }
@@ -577,33 +568,21 @@ MacroAssemblerMIPS::branchWithCode(InstImm code, Label* label, JumpKind jumpKind
     // Second word holds a pointer to the next branch in label's chain.
     uint32_t nextInChain = label->used() ? label->offset() : LabelBase::INVALID_OFFSET;
 
-    if (jumpKind == ShortJump) {
-        // Make the whole branch continous in the buffer.
-        m_buffer.ensureSpace(2 * sizeof(uint32_t));
+    // Make the whole branch continous in the buffer.
+    m_buffer.ensureSpace(4 * sizeof(uint32_t));
 
+    if (jumpKind == ShortJump) {
         // Indicate that this is short jump with offset 4.
         code.setBOffImm16(BOffImm16(4));
-        BufferOffset bo = writeInst(code.encode());
-        writeInst(nextInChain);
-        if (!oom())
-            label->use(bo.getOffset());
-        return;
     }
-
-    bool conditional = code.encode() != inst_beq.encode();
-
-    // Make the whole branch continous in the buffer.
-    m_buffer.ensureSpace((conditional ? 5 : 4) * sizeof(uint32_t));
-
     BufferOffset bo = writeInst(code.encode());
     writeInst(nextInChain);
     if (!oom())
         label->use(bo.getOffset());
-    // Leave space for potential long jump.
-    as_nop();
-    as_nop();
-    if (conditional)
+    if (jumpKind != ShortJump && code.encode() != inst_beq.encode()) {
         as_nop();
+        as_nop();
+    }
 }
 
 void
@@ -1597,13 +1576,12 @@ MacroAssemblerMIPSCompat::jumpWithPatch(RepatchLabel* label, Label* documentatio
 {
     // Only one branch per label.
     MOZ_ASSERT(!label->used());
-    uint32_t dest = label->bound() ? label->offset() : LabelBase::INVALID_OFFSET;
 
     BufferOffset bo = nextOffset();
     label->use(bo.getOffset());
-    addLongJump(bo);
-    ma_liPatchable(ScratchRegister, Imm32(dest));
-    as_jr(ScratchRegister);
+    if (label->bound())
+        addMixedJump(bo, ImmPtr((void*)label->offset()), MixedJumpPatch::PATCHABLE);
+    as_j(JOffImm26(0));
     as_nop();
     return CodeOffsetJump(bo.getOffset());
 }
diff --git a/js/src/jit/mips32/MacroAssembler-mips32.h b/js/src/jit/mips32/MacroAssembler-mips32.h
index fe36c66be..3b5c06399 100644
--- a/js/src/jit/mips32/MacroAssembler-mips32.h
+++ b/js/src/jit/mips32/MacroAssembler-mips32.h
@@ -91,25 +91,25 @@ class MacroAssemblerMIPS : public MacroAssemblerMIPSShared
 
     void branchWithCode(InstImm code, Label* label, JumpKind jumpKind);
     // branches when done from within mips-specific code
-    void ma_b(Register lhs, ImmWord imm, Label* l, Condition c, JumpKind jumpKind = LongJump)
+    void ma_b(Register lhs, ImmWord imm, Label* l, Condition c, JumpKind jumpKind = MixedJump)
     {
         ma_b(lhs, Imm32(uint32_t(imm.value)), l, c, jumpKind);
     }
-    void ma_b(Address addr, ImmWord imm, Label* l, Condition c, JumpKind jumpKind = LongJump)
+    void ma_b(Address addr, ImmWord imm, Label* l, Condition c, JumpKind jumpKind = MixedJump)
     {
         ma_b(addr, Imm32(uint32_t(imm.value)), l, c, jumpKind);
     }
 
-    void ma_b(Register lhs, Address addr, Label* l, Condition c, JumpKind jumpKind = LongJump);
-    void ma_b(Address addr, Imm32 imm, Label* l, Condition c, JumpKind jumpKind = LongJump);
-    void ma_b(Address addr, ImmGCPtr imm, Label* l, Condition c, JumpKind jumpKind = LongJump);
-    void ma_b(Address addr, Register rhs, Label* l, Condition c, JumpKind jumpKind = LongJump) {
+    void ma_b(Register lhs, Address addr, Label* l, Condition c, JumpKind jumpKind = MixedJump);
+    void ma_b(Address addr, Imm32 imm, Label* l, Condition c, JumpKind jumpKind = MixedJump);
+    void ma_b(Address addr, ImmGCPtr imm, Label* l, Condition c, JumpKind jumpKind = MixedJump);
+    void ma_b(Address addr, Register rhs, Label* l, Condition c, JumpKind jumpKind = MixedJump) {
         MOZ_ASSERT(rhs != ScratchRegister);
         ma_load(ScratchRegister, addr, SizeWord);
         ma_b(ScratchRegister, rhs, l, c, jumpKind);
     }
 
-    void ma_bal(Label* l, DelaySlotFill delaySlotFill = FillDelaySlot);
+    void ma_jal(Label* l);
 
     // fp instructions
     void ma_lid(FloatRegister dest, double value);