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Switched optimizetempvarspass to use single use and def instr value i…
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…nstead of maintaining

temporary lists for all uses and defs.  This reduces number of arraylists from this pass
by 175000 while running rails console on an empty Rails app.
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enebo committed Jan 8, 2015
1 parent 200de99 commit e1ffae8
Showing 1 changed file with 23 additions and 30 deletions.
53 changes: 23 additions & 30 deletions core/src/main/java/org/jruby/ir/passes/OptimizeTempVarsPass.java
Original file line number Diff line number Diff line change
Expand Up @@ -51,38 +51,37 @@ private static void optimizeTmpVars(IRScope s) {
if (s.getCFG() != null) return;

// Pass 1: Analyze instructions and find use and def count of temporary variables
Map<TemporaryVariable, List<Instr>> tmpVarUses = new HashMap<TemporaryVariable, List<Instr>>();
Map<TemporaryVariable, List<Instr>> tmpVarDefs = new HashMap<TemporaryVariable, List<Instr>>();
Map<TemporaryVariable, Instr> tmpVarUses = new HashMap<>();
Map<TemporaryVariable, Instr> tmpVarDefs = new HashMap<>();
for (Instr i: s.getInstrs()) {
for (Variable v: i.getUsedVariables()) {
if (v instanceof TemporaryVariable) {
TemporaryVariable tv = (TemporaryVariable)v;
List<Instr> uses = tmpVarUses.get(tv);
if (uses == null) {
uses = new ArrayList<Instr>();
tmpVarUses.put(tv, uses);
Instr use = tmpVarUses.get(tv);
if (use == null) {
tmpVarUses.put(tv, i);
} else if (use != NopInstr.NOP) {
tmpVarUses.put(tv, NopInstr.NOP);
}
uses.add(i);
}
}
if (i instanceof ResultInstr) {
Variable v = ((ResultInstr)i).getResult();
if (v instanceof TemporaryVariable) {
TemporaryVariable tv = (TemporaryVariable)v;
List<Instr> defs = tmpVarDefs.get(tv);
Instr defs = tmpVarDefs.get(tv);
if (defs == null) {
defs = new ArrayList<Instr>();
tmpVarDefs.put(tv, defs);
} else if (defs != NopInstr.NOP) {
tmpVarDefs.put(tv, NopInstr.NOP);
}
defs.add(i);
}
}
}

// Pass 2: Transform code and do additional analysis:
// * If the result of this instr. has not been used, mark it dead
// * Find copies where constant values are set
Map<TemporaryVariable, Variable> removableCopies = new HashMap<TemporaryVariable, Variable>();
ListIterator<Instr> instrs = s.getInstrs().listIterator();
while (instrs.hasNext()) {
Instr i = instrs.next();
Expand All @@ -93,9 +92,9 @@ private static void optimizeTmpVars(IRScope s) {
// Deal with this code pattern:
// %v = ...
// %v not used anywhere
List<Instr> uses = tmpVarUses.get((TemporaryVariable)v);
List<Instr> defs = tmpVarDefs.get((TemporaryVariable)v);
if (uses == null) {
Instr use = tmpVarUses.get(v);
Instr def = tmpVarDefs.get(v);
if (use == null) {
if (i instanceof CopyInstr) {
i.markDead();
instrs.remove();
Expand All @@ -108,13 +107,8 @@ private static void optimizeTmpVars(IRScope s) {
// i.markUnusedResult();
}
}
// Deal with this code pattern:
// %v = <some-operand>
// .... %v ...
// %v not used or defined anywhere else
// So, %v can be replaced by the operand
else if ((uses.size() == 1) && (defs != null) && (defs.size() == 1) && (i instanceof CopyInstr)) {
Instr soleUse = uses.get(0);
// Replace <operand> in use from def if single-def and single-use: %v = <operand>; ... %v ...
else if (use != NopInstr.NOP && def != null && def != NopInstr.NOP && i instanceof CopyInstr) {
// Conservatively avoid optimizing return values since
// intervening cloned ensure block code can modify the
// copy source (if it is a variable).
Expand All @@ -126,16 +120,16 @@ else if ((uses.size() == 1) && (defs != null) && (defs.size() == 1) && (i instan
// v = 2
// return %v_1 <-- cannot be replaced with v
// ....
if (!(soleUse instanceof ReturnInstr)) {
if (!(use instanceof ReturnInstr)) {
CopyInstr ci = (CopyInstr)i;
Operand src = ci.getSource();
i.markDead();
instrs.remove();

// Fix up use
Map<Operand, Operand> copyMap = new HashMap<Operand, Operand>();
Map<Operand, Operand> copyMap = new HashMap<>();
copyMap.put(v, src);
soleUse.simplifyOperands(copyMap, true);
use.simplifyOperands(copyMap, true);
}
}
}
Expand All @@ -154,13 +148,12 @@ else if (i instanceof CopyInstr) {
Operand src = ci.getSource();
if (src instanceof TemporaryVariable) {
TemporaryVariable vsrc = (TemporaryVariable)src;
List<Instr> uses = tmpVarUses.get(vsrc);
List<Instr> defs = tmpVarDefs.get(vsrc);
if ((uses.size() == 1) && (defs.size() == 1)) {
Instr soleDef = defs.get(0);
if (!soleDef.isDead()) {
Instr use = tmpVarUses.get(vsrc);
Instr def = tmpVarDefs.get(vsrc);
if ((use != null && use != NopInstr.NOP) && (def != null && def != NopInstr.NOP)) {
if (!def.isDead()) {
// Fix up def
((ResultInstr)soleDef).updateResult(ci.getResult());
((ResultInstr) def).updateResult(ci.getResult());
ci.markDead();
instrs.remove();
}
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