public SwitchBlock(NodeBlock source, ControlBlock defaultCase, List <Case> cases, ControlBlock join)
: base(source)
{
defaultCase_ = defaultCase;
cases_ = cases;
join_ = join;
}
public WhileLoop(ControlType type, NodeBlock source, ControlBlock body, ControlBlock join)
: base(source)
{
body_ = body;
join_ = join;
type_ = type;
}
public WhileLoop(ControlType type, LogicChain logic, ControlBlock body, ControlBlock join)
: base(null)
{
body_ = body;
join_ = join;
logic_ = logic;
type_ = type;
}
public IfBlock(NodeBlock source, bool invert, ControlBlock trueArm, ControlBlock falseArm, ControlBlock join)
: base(source)
{
trueArm_ = trueArm;
falseArm_ = falseArm;
join_ = join;
invert_ = invert;
}
public void write(ControlBlock root)
{
writeSignature(root.source);
outputLine("{");
increaseIndent();
writeBlock(root);
decreaseIndent();
outputLine("}");
}
public IfBlock(NodeBlock source, LogicChain chain, ControlBlock trueArm, ControlBlock falseArm, ControlBlock join)
: base(source)
{
trueArm_ = trueArm;
falseArm_ = falseArm;
join_ = join;
invert_ = invert;
logic_ = logic;
}
private IfBlock traverseIf(NodeBlock block, DJumpCondition jcc)
{
if (HasSharedTarget(block, jcc))
{
return(traverseComplexIf(block, jcc));
}
NodeBlock trueTarget = (jcc.spop == SPOpcode.jzer) ? jcc.falseTarget : jcc.trueTarget;
NodeBlock falseTarget = (jcc.spop == SPOpcode.jzer) ? jcc.trueTarget : jcc.falseTarget;
NodeBlock joinTarget = findJoinOfSimpleIf(block, jcc);
// If there is no join block (both arms terminate control flow),
// eliminate one arm and use the other as a join point.
if (joinTarget == null)
{
joinTarget = falseTarget;
}
// If the false target is equivalent to the join point, eliminate
// it.
if (BlockAnalysis.EffectiveTarget(falseTarget) == joinTarget)
{
falseTarget = null;
}
// If the true target is equivalent to the join point, promote
// the false target to the true target and undo the inversion.
bool invert = false;
if (BlockAnalysis.EffectiveTarget(trueTarget) == joinTarget)
{
trueTarget = falseTarget;
falseTarget = null;
invert ^= true;
}
// If there is always a true target and a join target.
pushScope(joinTarget);
ControlBlock trueArm = traverseBlock(trueTarget);
popScope();
ControlBlock joinArm = traverseJoin(joinTarget);
if (falseTarget == null)
{
return(new IfBlock(block, invert, trueArm, joinArm));
}
pushScope(joinTarget);
ControlBlock falseArm = traverseBlock(falseTarget);
popScope();
return(new IfBlock(block, invert, trueArm, falseArm, joinArm));
}
private ControlBlock traverseLoop(NodeBlock block)
{
DNode last = block.nodes.last;
NodeBlock effectiveHeader = block;
LogicChain chain = null;
if (last.type == NodeType.JumpCondition)
{
DJumpCondition jcc = (DJumpCondition)last;
if (HasSharedTarget(block, jcc))
{
chain = buildLogicChain(block, null, out effectiveHeader);
}
}
last = effectiveHeader.nodes.last;
//Debug.Assert(last.type == NodeType.JumpCondition);
if (last.type == NodeType.JumpCondition)
{
// Assert that the backedge is a straight jump.
//Debug.Assert(BlockAnalysis.GetSingleTarget(graph_[block.lir.backedge.id]) == block);
NodeBlock join, body, cond;
ControlType type = findLoopJoinAndBody(block, effectiveHeader, out join, out body, out cond);
ControlBlock joinArm = traverseBlock(join);
ControlBlock bodyArm = null;
if (body != null)
{
pushScope(block);
pushScope(cond);
bodyArm = traverseBlockNoLoop(body);
popScope();
popScope();
}
if (chain != null)
{
return(new WhileLoop(type, chain, bodyArm, joinArm));
}
return(new WhileLoop(type, cond, bodyArm, joinArm));
}
return(null);
}
private ControlBlock traverseSwitch(NodeBlock block, DSwitch switch_)
{
var dominators = new List <LBlock>();
for (int i = 0; i < block.lir.idominated.Length; i++)
{
dominators.Add(block.lir.idominated[i]);
}
dominators.Remove(switch_.defaultCase);
for (int i = 0; i < switch_.numCases; i++)
{
dominators.Remove(switch_.getCase(i).target);
}
NodeBlock join = null;
if (dominators.Count > 0)
{
//Debug.Assert(dominators.Count == 1);
join = graph_[dominators[dominators.Count - 1].id];
}
ControlBlock joinArm = null;
if (join != null)
{
joinArm = traverseBlock(join);
}
pushScope(join);
var cases = new List <SwitchBlock.Case>();
ControlBlock defaultArm = traverseBlock(graph_[switch_.defaultCase.id]);
for (int i = 0; i < switch_.numCases; i++)
{
ControlBlock arm = traverseBlock(graph_[switch_.getCase(i).target.id]);
cases.Add(new SwitchBlock.Case(switch_.getCase(i).value, arm));
}
popScope();
return(new SwitchBlock(block, defaultArm, cases, joinArm));
}
private void writeBlock(ControlBlock block)
{
if (block == null)
{
return;
}
switch (block.type)
{
case ControlType.If:
writeIf((IfBlock)block);
break;
case ControlType.WhileLoop:
writeWhileLoop((WhileLoop)block);
break;
case ControlType.DoWhileLoop:
writeDoWhileLoop((WhileLoop)block);
break;
case ControlType.Statement:
writeStatementBlock((StatementBlock)block);
break;
case ControlType.Return:
writeStatements(block.source);
writeReturn((DReturn)block.source.nodes.last);
break;
case ControlType.Switch:
writeSwitch((SwitchBlock)block);
break;
default:
Debug.Assert(false);
break;
}
}
private ControlBlock traverseBlockNoLoop(NodeBlock block)
{
if (block == null)
{
return(null);
}
DNode last = block.nodes.last;
if (last.type == NodeType.JumpCondition)
{
return(traverseIf(block, (DJumpCondition)last));
}
if (last.type == NodeType.Jump)
{
DJump jump = (DJump)last;
NodeBlock target = BlockAnalysis.EffectiveTarget(jump.target);
ControlBlock next = null;
if (!isJoin(target))
{
next = traverseBlock(target);
}
return(new StatementBlock(block, next));
}
if (last.type == NodeType.Switch)
{
return(traverseSwitch(block, (DSwitch)last));
}
//Debug.Assert(last.type == NodeType.Return);
return(new ReturnBlock(block));
}
public void write(ControlBlock root)
{
writeSignature(root.source);
outputLine("{");
increaseIndent();
writeBlock(root);
decreaseIndent();
outputLine("}");
}
public Case(int value, ControlBlock target)
{
value_ = value;
target_ = target;
}
public StatementBlock(NodeBlock source, ControlBlock next)
: base(source)
{
next_ = next;
}
public SwitchBlock(NodeBlock source, ControlBlock defaultCase, List<Case> cases, ControlBlock join)
: base(source)
{
defaultCase_ = defaultCase;
cases_ = cases;
join_ = join;
}
public Case(int value, ControlBlock target)
{
value_ = value;
target_ = target;
}
public WhileLoop(ControlType type, LogicChain logic, ControlBlock body, ControlBlock join)
: base(null)
{
body_ = body;
join_ = join;
logic_ = logic;
type_ = type;
}
public WhileLoop(ControlType type, NodeBlock source, ControlBlock body, ControlBlock join)
: base(source)
{
body_ = body;
join_ = join;
type_ = type;
}
public IfBlock(NodeBlock source, LogicChain chain, ControlBlock trueArm, ControlBlock falseArm, ControlBlock join)
: base(source)
{
trueArm_ = trueArm;
falseArm_ = falseArm;
join_ = join;
invert_ = invert;
logic_ = logic;
}
public IfBlock(NodeBlock source, bool invert, ControlBlock trueArm, ControlBlock falseArm, ControlBlock join)
: base(source)
{
trueArm_ = trueArm;
falseArm_ = falseArm;
join_ = join;
invert_ = invert;
}
public StatementBlock(NodeBlock source, ControlBlock next)
: base(source)
{
next_ = next;
}
private void writeBlock(ControlBlock block)
{
if (block == null)
{
return;
}
switch (block.type)
{
case ControlType.If:
writeIf((IfBlock)block);
break;
case ControlType.WhileLoop:
writeWhileLoop((WhileLoop)block);
break;
case ControlType.DoWhileLoop:
writeDoWhileLoop((WhileLoop)block);
break;
case ControlType.Statement:
writeStatementBlock((StatementBlock)block);
break;
case ControlType.Return:
writeStatements(block.source);
writeReturn((DReturn)block.source.nodes.last);
break;
case ControlType.Switch:
writeSwitch((SwitchBlock)block);
break;
default:
Debug.Assert(false);
break;
}
}
private IfBlock traverseComplexIf(NodeBlock block, DJumpCondition jcc)
{
// Degenerate case: using || or &&, or any combination thereof,
// will generate a chain of n+1 conditional blocks, where each
// |n| has a target to a shared "success" block, setting a
// phony variable. We decompose this giant mess into the intended
// sequence of expressions.
NodeBlock join;
LogicChain chain = buildLogicChain(block, null, out join);
DJumpCondition finalJcc = (DJumpCondition)join.nodes.last;
//Debug.Assert(finalJcc.spop == SPOpcode.jzer);
// The final conditional should have the normal dominator
// properties: 2 or 3 idoms, depending on the number of arms.
// Because of critical edge splitting, we may have 3 idoms
// even if there are only actually two arms.
NodeBlock joinBlock = findJoinOfSimpleIf(join, finalJcc);
// If an AND chain reaches its end, the result is 1. jzer tests
// for zero, so this is effectively testing (!success).
// If an OR expression reaches its end, the result is 0. jzer
// tests for zero, so this is effectively testing if (failure).
//
// In both cases, the true target represents a failure, so flip
// the targets around.
NodeBlock trueBlock = finalJcc.falseTarget;
NodeBlock falseBlock = finalJcc.trueTarget;
// If there is no join block, both arms terminate control flow,
// eliminate one arm and use the other as a join point.
if (joinBlock == null)
{
joinBlock = falseBlock;
}
if (join.lir.idominated.Length == 2 ||
BlockAnalysis.EffectiveTarget(falseBlock) == joinBlock)
{
if (join.lir.idominated.Length == 3)
{
joinBlock = BlockAnalysis.EffectiveTarget(falseBlock);
}
// One-armed structure.
pushScope(joinBlock);
ControlBlock trueArm1 = traverseBlock(trueBlock);
popScope();
ControlBlock joinArm1 = traverseBlock(joinBlock);
return(new IfBlock(block, chain, trueArm1, joinArm1));
}
//Debug.Assert(join.lir.idominated.Length == 3);
pushScope(joinBlock);
ControlBlock trueArm2 = traverseBlock(trueBlock);
ControlBlock falseArm = traverseBlock(falseBlock);
popScope();
ControlBlock joinArm2 = traverseBlock(joinBlock);
return(new IfBlock(block, chain, trueArm2, falseArm, joinArm2));
}
