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Unified Diff: src/compiler/typer.cc

Issue 2260153002: [turbofan] Induction variable decrement bound analysis. (Closed) Base URL: https://chromium.googlesource.com/v8/v8.git@DeleteUnusedVar
Patch Set: Add test for non-constant bound. Created 4 years, 4 months ago
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Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index 37d9a94006ff7a7501fc9bb93bdd81da26215db2..288df95b2f4841b4e96b8416481b394a820a4c34 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -651,9 +651,27 @@ Type* Typer::Visitor::TypeInductionVariablePhi(Node* node) {
DCHECK(res != induction_vars_->induction_variables().end());
InductionVariable* induction_var = res->second;
+ InductionVariable::ArithmeticType arithmetic_type = induction_var->Type();
+
double min = -V8_INFINITY;
double max = V8_INFINITY;
- if (increment_type->Min() >= 0) {
+
+ double increment_min;
+ double increment_max;
+ if (arithmetic_type == InductionVariable::ArithmeticType::kAddition) {
+ increment_min = increment_type->Min();
+ increment_max = increment_type->Max();
+ } else {
+ DCHECK(arithmetic_type == InductionVariable::ArithmeticType::kSubtraction);
+ increment_min = -increment_type->Max();
+ increment_max = -increment_type->Min();
+ }
+
+ if ((increment_type->Min() >= 0 &&
+ arithmetic_type == InductionVariable::ArithmeticType::kAddition) ||
+ (increment_type->Max() <= 0 &&
+ arithmetic_type == InductionVariable::ArithmeticType::kSubtraction)) {
Jarin 2016/08/22 07:27:20 How about if (increment_min >= 0) {
Franzi 2016/08/22 09:06:30 Thanks!
+ // increasing sequence (add positive values, or subtract negative values)
min = initial_type->Min();
for (auto bound : induction_var->upper_bounds()) {
Type* bound_type = TypeOrNone(bound.bound);
@@ -668,11 +686,17 @@ Type* Typer::Visitor::TypeInductionVariablePhi(Node* node) {
if (bound.kind == InductionVariable::kStrict) {
bound_max -= 1;
}
- max = std::min(max, bound_max + increment_type->Max());
+ max = std::min(max, bound_max + increment_max);
}
// The upper bound must be at least the initial value's upper bound.
max = std::max(max, initial_type->Max());
- } else if (increment_type->Max() <= 0) {
+ } else if ((increment_type->Max() <= 0 &&
+ arithmetic_type ==
+ InductionVariable::ArithmeticType::kAddition) ||
+ (increment_type->Min() >= 0 &&
+ arithmetic_type ==
+ InductionVariable::ArithmeticType::kSubtraction)) {
+ // decreasing sequence (add negative values, or subtract positive values)
Jarin 2016/08/22 07:27:19 } else if (increment_max <= 0) {
Franzi 2016/08/22 09:06:30 Done.
max = initial_type->Max();
for (auto bound : induction_var->lower_bounds()) {
Type* bound_type = TypeOrNone(bound.bound);
@@ -687,7 +711,7 @@ Type* Typer::Visitor::TypeInductionVariablePhi(Node* node) {
if (bound.kind == InductionVariable::kStrict) {
bound_min += 1;
}
- min = std::max(min, bound_min + increment_type->Min());
+ min = std::max(min, bound_min + increment_min);
}
// The lower bound must be at most the initial value's lower bound.
min = std::min(min, initial_type->Min());
@@ -700,8 +724,11 @@ Type* Typer::Visitor::TypeInductionVariablePhi(Node* node) {
OFStream os(stdout);
os << std::setprecision(10);
os << "Loop (" << NodeProperties::GetControlInput(node)->id()
- << ") variable bounds for phi " << node->id() << ": (" << min << ", "
- << max << ")\n";
+ << ") variable bounds in "
+ << (arithmetic_type == InductionVariable::ArithmeticType::kAddition
+ ? "addition"
+ : "subtraction")
+ << " for phi " << node->id() << ": (" << min << ", " << max << ")\n";
}
return Type::Range(min, max, typer_->zone());
}

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