| /* |
| * Copyright (C) 2009 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "Dalvik.h" |
| #include "vm/compiler/CompilerInternals.h" |
| #include "ArmLIR.h" |
| |
| /* |
| * Identify unconditional branches that jump to the immediate successor of the |
| * branch itself. |
| */ |
| static void applyRedundantBranchElimination(CompilationUnit *cUnit) |
| { |
| ArmLIR *thisLIR; |
| |
| for (thisLIR = (ArmLIR *) cUnit->firstLIRInsn; |
| thisLIR != (ArmLIR *) cUnit->lastLIRInsn; |
| thisLIR = NEXT_LIR(thisLIR)) { |
| |
| /* Branch to the next instruction */ |
| if (thisLIR->opcode == kThumbBUncond) { |
| ArmLIR *nextLIR = thisLIR; |
| |
| while (true) { |
| nextLIR = NEXT_LIR(nextLIR); |
| |
| /* |
| * Is the branch target the next instruction? |
| */ |
| if (nextLIR == (ArmLIR *) thisLIR->generic.target) { |
| thisLIR->flags.isNop = true; |
| break; |
| } |
| |
| /* |
| * Found real useful stuff between the branch and the target. |
| * Need to explicitly check the lastLIRInsn here since with |
| * method-based JIT the branch might be the last real |
| * instruction. |
| */ |
| if (!isPseudoOpcode(nextLIR->opcode) || |
| (nextLIR = (ArmLIR *) cUnit->lastLIRInsn)) |
| break; |
| } |
| } |
| } |
| } |
| |
| void dvmCompilerApplyGlobalOptimizations(CompilationUnit *cUnit) |
| { |
| applyRedundantBranchElimination(cUnit); |
| } |