ART: Fix issues with SplitBlock
The SplitBlock is a public interface from MIRGraph to be able to create two
blocks from one. This interface can be called not just during the control
flow graph building phase, but later. At that later point, extended instructions
may have already been inserted.
For example, SpecialMethodInliner can insert kMirOpNullCheck and kMirOpNop,
and then another pass tries to split block that contains this. The DCHECK
will fail even though the split is semantically correct.
Signed-off-by: Mathew Zaleski <mathew.zaleski@intel.com>
Conflicts:
compiler/dex/mir_graph.cc
Change-Id: I8bb3551407907909cda444a3379da2eb9331b9ff
diff --git a/compiler/dex/mir_graph.cc b/compiler/dex/mir_graph.cc
index bcbfb5a..078f381 100644
--- a/compiler/dex/mir_graph.cc
+++ b/compiler/dex/mir_graph.cc
@@ -178,7 +178,7 @@
BasicBlock* orig_block, BasicBlock** immed_pred_block_p) {
DCHECK_GT(code_offset, orig_block->start_offset);
MIR* insn = orig_block->first_mir_insn;
- MIR* prev = NULL;
+ MIR* prev = NULL; // Will be set to instruction before split.
while (insn) {
if (insn->offset == code_offset) break;
prev = insn;
@@ -187,6 +187,10 @@
if (insn == NULL) {
LOG(FATAL) << "Break split failed";
}
+ // Now insn is at the instruction where we want to split, namely
+ // insn will be the first instruction of the "bottom" block.
+ // Similarly, prev will be the last instruction of the "top" block
+
BasicBlock* bottom_block = CreateNewBB(kDalvikByteCode);
bottom_block->start_offset = code_offset;
@@ -259,7 +263,10 @@
DCHECK(static_cast<int>(insn->dalvikInsn.opcode) == kMirOpCheck ||
!MIR::DecodedInstruction::IsPseudoMirOp(insn->dalvikInsn.opcode));
DCHECK_EQ(dex_pc_to_block_map_[insn->offset], orig_block->id);
+ // Scan the "bottom" instructions, remapping them to the
+ // newly created "bottom" block.
MIR* p = insn;
+ p->bb = bottom_block->id;
dex_pc_to_block_map_[p->offset] = bottom_block->id;
while (p != bottom_block->last_mir_insn) {
p = p->next;
@@ -273,7 +280,11 @@
* the first in a BasicBlock, we can't hit it here.
*/
if ((opcode == kMirOpCheck) || !MIR::DecodedInstruction::IsPseudoMirOp(opcode)) {
- DCHECK_EQ(dex_pc_to_block_map_[p->offset], orig_block->id);
+ BasicBlockId mapped_id = dex_pc_to_block_map_[p->offset];
+ // At first glance the instructions should all be mapped to orig_block.
+ // However, multiple instructions may correspond to the same dex, hence an earlier
+ // instruction may have already moved the mapping for dex to bottom_block.
+ DCHECK((mapped_id == orig_block->id) || (mapped_id == bottom_block->id));
dex_pc_to_block_map_[p->offset] = bottom_block->id;
}
}