diff options
Diffstat (limited to 'compiler/dex')
| -rw-r--r-- | compiler/dex/dex_to_dex_compiler.cc | 85 |
1 files changed, 58 insertions, 27 deletions
diff --git a/compiler/dex/dex_to_dex_compiler.cc b/compiler/dex/dex_to_dex_compiler.cc index ee68a5d..4419fed 100644 --- a/compiler/dex/dex_to_dex_compiler.cc +++ b/compiler/dex/dex_to_dex_compiler.cc @@ -30,8 +30,8 @@ namespace optimizer { // Controls quickening activation. const bool kEnableQuickening = true; -// Controls logging. -const bool kEnableLogging = false; +// Control check-cast elision. +const bool kEnableCheckCastEllision = true; class DexCompiler { public: @@ -59,6 +59,11 @@ class DexCompiler { // a barrier is required. void CompileReturnVoid(Instruction* inst, uint32_t dex_pc); + // Compiles a CHECK-CAST into 2 NOP instructions if it is known to be safe. In + // this case, returns the second NOP instruction pointer. Otherwise, returns + // the given "inst". + Instruction* CompileCheckCast(Instruction* inst, uint32_t dex_pc); + // Compiles a field access into a quick field access. // The field index is replaced by an offset within an Object where we can read // from / write to this field. Therefore, this does not involve any resolution @@ -145,6 +150,10 @@ void DexCompiler::Compile() { CompileReturnVoid(inst, dex_pc); break; + case Instruction::CHECK_CAST: + inst = CompileCheckCast(inst, dex_pc); + break; + case Instruction::IGET: CompileInstanceFieldAccess(inst, dex_pc, Instruction::IGET_QUICK, false); break; @@ -202,16 +211,44 @@ void DexCompiler::CompileReturnVoid(Instruction* inst, uint32_t dex_pc) { return; } // Replace RETURN_VOID by RETURN_VOID_BARRIER. - if (kEnableLogging) { - LOG(INFO) << "Replacing " << Instruction::Name(inst->Opcode()) - << " by " << Instruction::Name(Instruction::RETURN_VOID_BARRIER) - << " at dex pc " << StringPrintf("0x%x", dex_pc) << " in method " - << PrettyMethod(unit_.GetDexMethodIndex(), GetDexFile(), true); - } + VLOG(compiler) << "Replacing " << Instruction::Name(inst->Opcode()) + << " by " << Instruction::Name(Instruction::RETURN_VOID_BARRIER) + << " at dex pc " << StringPrintf("0x%x", dex_pc) << " in method " + << PrettyMethod(unit_.GetDexMethodIndex(), GetDexFile(), true); ScopedDexWriteAccess sdwa(GetModifiableDexFile(), inst, 2u); inst->SetOpcode(Instruction::RETURN_VOID_BARRIER); } +Instruction* DexCompiler::CompileCheckCast(Instruction* inst, uint32_t dex_pc) { + if (!kEnableCheckCastEllision) { + return inst; + } + MethodReference referrer(&GetDexFile(), unit_.GetDexMethodIndex()); + if (!driver_.IsSafeCast(referrer, dex_pc)) { + return inst; + } + // Ok, this is a safe cast. Since the "check-cast" instruction size is 2 code + // units and a "nop" instruction size is 1 code unit, we need to replace it by + // 2 consecutive NOP instructions. + // Because the caller loops over instructions by calling Instruction::Next onto + // the current instruction, we need to return the 2nd NOP instruction. Indeed, + // its next instruction is the former check-cast's next instruction. + VLOG(compiler) << "Removing " << Instruction::Name(inst->Opcode()) + << " by replacing it with 2 NOPs at dex pc " + << StringPrintf("0x%x", dex_pc) << " in method " + << PrettyMethod(unit_.GetDexMethodIndex(), GetDexFile(), true); + // We are modifying 4 consecutive bytes. + ScopedDexWriteAccess sdwa(GetModifiableDexFile(), inst, 4u); + inst->SetOpcode(Instruction::NOP); + inst->SetVRegA_10x(0u); // keep compliant with verifier. + // Get to next instruction which is the second half of check-cast and replace + // it by a NOP. + inst = const_cast<Instruction*>(inst->Next()); + inst->SetOpcode(Instruction::NOP); + inst->SetVRegA_10x(0u); // keep compliant with verifier. + return inst; +} + void DexCompiler::CompileInstanceFieldAccess(Instruction* inst, uint32_t dex_pc, Instruction::Code new_opcode, @@ -225,15 +262,12 @@ void DexCompiler::CompileInstanceFieldAccess(Instruction* inst, bool fast_path = driver_.ComputeInstanceFieldInfo(field_idx, &unit_, field_offset, is_volatile, is_put); if (fast_path && !is_volatile && IsUint(16, field_offset)) { - // TODO: use VLOG ? - if (kEnableLogging) { - LOG(INFO) << "Quickening " << Instruction::Name(inst->Opcode()) - << " to " << Instruction::Name(new_opcode) - << " by replacing field index " << field_idx - << " by field offset " << field_offset - << " at dex pc " << StringPrintf("0x%x", dex_pc) << " in method " - << PrettyMethod(unit_.GetDexMethodIndex(), GetDexFile(), true); - } + VLOG(compiler) << "Quickening " << Instruction::Name(inst->Opcode()) + << " to " << Instruction::Name(new_opcode) + << " by replacing field index " << field_idx + << " by field offset " << field_offset + << " at dex pc " << StringPrintf("0x%x", dex_pc) << " in method " + << PrettyMethod(unit_.GetDexMethodIndex(), GetDexFile(), true); // We are modifying 4 consecutive bytes. ScopedDexWriteAccess sdwa(GetModifiableDexFile(), inst, 4u); inst->SetOpcode(new_opcode); @@ -263,16 +297,13 @@ void DexCompiler::CompileInvokeVirtual(Instruction* inst, // TODO: support devirtualization. if (fast_path && original_invoke_type == invoke_type) { if (vtable_idx >= 0 && IsUint(16, vtable_idx)) { - // TODO: use VLOG ? - if (kEnableLogging) { - LOG(INFO) << "Quickening " << Instruction::Name(inst->Opcode()) - << "(" << PrettyMethod(method_idx, GetDexFile(), true) << ")" - << " to " << Instruction::Name(new_opcode) - << " by replacing method index " << method_idx - << " by vtable index " << vtable_idx - << " at dex pc " << StringPrintf("0x%x", dex_pc) << " in method " - << PrettyMethod(unit_.GetDexMethodIndex(), GetDexFile(), true); - } + VLOG(compiler) << "Quickening " << Instruction::Name(inst->Opcode()) + << "(" << PrettyMethod(method_idx, GetDexFile(), true) << ")" + << " to " << Instruction::Name(new_opcode) + << " by replacing method index " << method_idx + << " by vtable index " << vtable_idx + << " at dex pc " << StringPrintf("0x%x", dex_pc) << " in method " + << PrettyMethod(unit_.GetDexMethodIndex(), GetDexFile(), true); // We are modifying 4 consecutive bytes. ScopedDexWriteAccess sdwa(GetModifiableDexFile(), inst, 4u); inst->SetOpcode(new_opcode); |