diff options
| -rw-r--r-- | compiler/optimizing/ssa_builder.cc | 18 | ||||
| -rw-r--r-- | compiler/optimizing/ssa_test.cc | 30 | ||||
| -rw-r--r-- | test/402-optimizing-control-flow/src/Main.java | 13 |
3 files changed, 58 insertions, 3 deletions
diff --git a/compiler/optimizing/ssa_builder.cc b/compiler/optimizing/ssa_builder.cc index 33084df94b..1284a97cd1 100644 --- a/compiler/optimizing/ssa_builder.cc +++ b/compiler/optimizing/ssa_builder.cc @@ -95,14 +95,26 @@ void SsaBuilder::VisitBasicBlock(HBasicBlock* block) { // All predecessors have already been visited because we are visiting in reverse post order. // We merge the values of all locals, creating phis if those values differ. for (size_t local = 0; local < current_locals_->Size(); local++) { + bool one_predecessor_has_no_value = false; bool is_different = false; HInstruction* value = ValueOfLocal(block->GetPredecessors().Get(0), local); - for (size_t i = 1; i < block->GetPredecessors().Size(); i++) { - if (ValueOfLocal(block->GetPredecessors().Get(i), local) != value) { + + for (size_t i = 0, e = block->GetPredecessors().Size(); i < e; ++i) { + HInstruction* current = ValueOfLocal(block->GetPredecessors().Get(i), local); + if (current == nullptr) { +// one_predecessor_has_no_value = true; +// break; + } else if (current != value) { is_different = true; - break; } } + + if (one_predecessor_has_no_value) { + // If one predecessor has no value for this local, we trust the verifier has + // successfully checked that there is a store dominating any read after this block. + continue; + } + if (is_different) { HPhi* phi = new (GetGraph()->GetArena()) HPhi( GetGraph()->GetArena(), local, block->GetPredecessors().Size(), Primitive::kPrimVoid); diff --git a/compiler/optimizing/ssa_test.cc b/compiler/optimizing/ssa_test.cc index d10461980d..485ea279ad 100644 --- a/compiler/optimizing/ssa_test.cc +++ b/compiler/optimizing/ssa_test.cc @@ -459,4 +459,34 @@ TEST(SsaTest, DeadLocal) { TestCode(data, expected); } +TEST(SsaTest, LocalInIf) { + // Test that we do not create a phi in the join block when one predecessor + // does not update the local. + const char* expected = + "BasicBlock 0, succ: 1\n" + " 0: IntConstant 0 [3, 3]\n" + " 1: IntConstant 4\n" + " 2: Goto\n" + "BasicBlock 1, pred: 0, succ: 2, 5\n" + " 3: Equal(0, 0) [4]\n" + " 4: If(3)\n" + "BasicBlock 2, pred: 1, succ: 3\n" + " 5: Goto\n" + "BasicBlock 3, pred: 2, 5, succ: 4\n" + " 6: ReturnVoid\n" + "BasicBlock 4, pred: 3\n" + " 7: Exit\n" + // Synthesized block to avoid critical edge. + "BasicBlock 5, pred: 1, succ: 3\n" + " 8: Goto\n"; + + const uint16_t data[] = TWO_REGISTERS_CODE_ITEM( + Instruction::CONST_4 | 0 | 0, + Instruction::IF_EQ, 3, + Instruction::CONST_4 | 4 << 12 | 1 << 8, + Instruction::RETURN_VOID); + + TestCode(data, expected); +} + } // namespace art diff --git a/test/402-optimizing-control-flow/src/Main.java b/test/402-optimizing-control-flow/src/Main.java index 3339ef436e..c9c24dd568 100644 --- a/test/402-optimizing-control-flow/src/Main.java +++ b/test/402-optimizing-control-flow/src/Main.java @@ -40,6 +40,9 @@ public class Main { result = $opt$testForLoop(42); expectEquals(44, result); + + result = $opt$testIfWithLocal(5); + expectEquals(7, result); } static int $opt$testIfEq1(int a) { @@ -73,4 +76,14 @@ public class Main { for (; a != 44; a++) {} return a; } + + static int $opt$testIfWithLocal(int a) { + if (a == 5) { + int f = 2; + a += f; + } + // The SSA builder should not create a phi for f. + + return a; + } } |