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Removing scope rules for pre block in 'For Loops'

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This commit is contained in:
fnatic 2019-04-06 00:08:23 +05:30
parent 94053c9a52
commit 5b6ed7a97c
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GPG Key ID: E125F2CAE4913F98
24 changed files with 60 additions and 111 deletions
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2
libyul/optimiser/CommonSubexpressionEliminator.h
View File

@ -32,7 +32,7 @@ struct Dialect;
* Optimisation stage that replaces expressions known to be the current value of a variable
* in scope by a reference to that variable.
*
* Prerequisite: Disambiguator
* Prerequisite: Disambiguator, ForLoopInitRewriter.
*/
class CommonSubexpressionEliminator: public DataFlowAnalyzer
{

9
libyul/optimiser/DataFlowAnalyzer.cpp
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@ -112,10 +112,9 @@ void DataFlowAnalyzer::operator()(FunctionDefinition& _fun)
void DataFlowAnalyzer::operator()(ForLoop& _for)
{
// Special scope handling of the pre block.
pushScope(false);
for (auto& statement: _for.pre.statements)
visit(statement);
// If the pre block was not empty,
// we would have to deal with more complicated scoping rules.
assertThrow(_for.pre.statements.empty(), OptimizerException, "");
AssignmentsSinceContinue assignmentsSinceCont;
assignmentsSinceCont(_for.body);
@ -130,8 +129,6 @@ void DataFlowAnalyzer::operator()(ForLoop& _for)
clearValues(assignmentsSinceCont.names());
(*this)(_for.post);
clearValues(assignments.names());
popScope();
}
void DataFlowAnalyzer::operator()(Block& _block)

2
libyul/optimiser/DataFlowAnalyzer.h
View File

@ -39,7 +39,7 @@ struct Dialect;
*
* A special zero constant expression is used for the default value of variables.
*
* Prerequisite: Disambiguator
* Prerequisite: Disambiguator, ForLoopInitRewriter.
*/
class DataFlowAnalyzer: public ASTModifier
{

2
libyul/optimiser/ExpressionSimplifier.h
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@ -36,7 +36,7 @@ struct Dialect;
* It tracks the current values of variables using the DataFlowAnalyzer
* and takes them into account for replacements.
*
* Prerequisite: Disambiguator.
* Prerequisite: Disambiguator, ForLoopInitRewriter.
*/
class ExpressionSimplifier: public DataFlowAnalyzer
{

13
libyul/optimiser/RedundantAssignEliminator.cpp
View File

@ -118,12 +118,9 @@ void RedundantAssignEliminator::operator()(ForLoop const& _forLoop)
ForLoopInfo outerForLoopInfo;
swap(outerForLoopInfo, m_forLoopInfo);
set<YulString> outerDeclaredVariables;
swap(m_declaredVariables, outerDeclaredVariables);
// We need to visit the statements directly because of the
// scoping rules.
walkVector(_forLoop.pre.statements);
// If the pre block was not empty,
// we would have to deal with more complicated scoping rules.
assertThrow(_forLoop.pre.statements.empty(), OptimizerException, "");
// We just run the loop twice to account for the
// back edge.
@ -156,10 +153,6 @@ void RedundantAssignEliminator::operator()(ForLoop const& _forLoop)
merge(m_assignments, move(m_forLoopInfo.pendingBreakStmts));
m_forLoopInfo.pendingBreakStmts.clear();
for (auto const& var: m_declaredVariables)
finalize(var, State::Unused);
swap(m_declaredVariables, outerDeclaredVariables);
// Restore potential outer for-loop states.
swap(m_forLoopInfo, outerForLoopInfo);
}

2
libyul/optimiser/RedundantAssignEliminator.h
View File

@ -95,7 +95,7 @@ struct Dialect;
* This step is usually run right after the SSA transform to complete
* the generation of the pseudo-SSA.
*
* Prerequisite: Disambiguator.
* Prerequisite: Disambiguator, ForLoopInitRewriter.
*/
class RedundantAssignEliminator: public ASTWalker
{

2
libyul/optimiser/Rematerialiser.h
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@ -33,7 +33,7 @@ namespace yul
* - the variable is referenced at most 5 times and the value is rather cheap
* ("cost" of at most 1 like a constant up to 0xff)
*
* Prerequisite: Disambiguator
* Prerequisite: Disambiguator, ForLoopInitRewriter.
*/
class Rematerialiser: public DataFlowAnalyzer
{

2
libyul/optimiser/StructuralSimplifier.h
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@ -36,7 +36,7 @@ namespace yul
* - replace switch with const expr with matching case body
* - replace for with false condition by its initialization part
*
* Prerequisites: Disambiguator
* Prerequisite: Disambiguator, ForLoopInitRewriter.
*
* Important: Can only be used on EVM code.
*/

3
test/libyul/yulOptimizerTests/commonSubexpressionEliminator/branches_for.yul
View File

@ -1,5 +1,6 @@
{
let a := 1 let b := codesize()
let a := 1
let b := codesize()
for { } lt(1, codesize()) { mstore(1, codesize()) a := add(a, codesize()) } {
mstore(1, codesize())
}

5
test/libyul/yulOptimizerTests/expressionSimplifier/inside_for.yul
View File

@ -1,12 +1,13 @@
{
for { let a := 10 } iszero(eq(a, 0)) { a := add(a, 1) } {}
let a := 10
for { } iszero(eq(a, 0)) { a := add(a, 1) } {}
}
// ====
// step: expressionSimplifier
// ----
// {
// let a := 10
// for {
// let a := 10
// }
// iszero(iszero(a))
// {

2
test/libyul/yulOptimizerTests/expressionSplitter/control_flow.yul
View File

@ -38,4 +38,4 @@
// sstore(b, _12)
// }
// }
// }
// }

13
test/libyul/yulOptimizerTests/fullInliner/not_inside_for.yul
View File

@ -1,5 +1,6 @@
{
for { let x := f(0) } f(x) { x := f(x) }
let x := f(0)
for { } f(x) { x := f(x) }
{
let t := f(x)
}
@ -13,12 +14,12 @@
// ----
// {
// {
// let a_3 := 0
// let r_4 := 0
// sstore(a_3, 0)
// r_4 := a_3
// let x := r_4
// for {
// let a_3 := 0
// let r_4 := 0
// sstore(a_3, 0)
// r_4 := a_3
// let x := r_4
// }
// f(x)
// {

3
test/libyul/yulOptimizerTests/fullSimplify/inside_for.yul
View File

@ -1,6 +1,7 @@
{
let x := calldataload(3)
for { let a := 10 } iszero(eq(a, sub(x, calldataload(3)))) { a := add(a, 1) } {}
let a := 10
for { } iszero(eq(a, sub(x, calldataload(3)))) { a := add(a, 1) } {}
}
// ====
// step: fullSimplify

10
test/libyul/yulOptimizerTests/redundantAssignEliminator/for.yul
View File

@ -1,9 +1,7 @@
{
let a := 2
a := 3
for {
let a := 2
// Should not be removed, even though you might think
// it goes out of scope
a := 3
} a { a := add(a, 1) }
{
a := 7
@ -13,9 +11,9 @@
// step: redundantAssignEliminator
// ----
// {
// let a := 2
// a := 3
// for {
// let a := 2
// a := 3
// }
// a
// {

5
test/libyul/yulOptimizerTests/rematerialiser/branches_for1.yul
View File

@ -1,6 +1,7 @@
{
let a := caller()
for { pop(a) } a { pop(a) } {
pop(a)
for { } a { pop(a) } {
pop(a)
}
}
@ -9,8 +10,8 @@
// ----
// {
// let a := caller()
// pop(caller())
// for {
// pop(caller())
// }
// caller()
// {

5
test/libyul/yulOptimizerTests/rematerialiser/branches_for2.yul
View File

@ -1,6 +1,7 @@
{
let a := caller()
for { pop(a) } a { pop(a) } {
pop(a)
for { } a { pop(a) } {
a := address()
let c := a
}
@ -11,8 +12,8 @@
// ----
// {
// let a := caller()
// pop(caller())
// for {
// pop(caller())
// }
// a
// {

24
test/libyul/yulOptimizerTests/rematerialiser/branches_for_declared_in_init1.yul
View File

@ -1,24 +0,0 @@
{
let b := 0
for { let a := caller() pop(a) } a { pop(a) } {
b := 1 pop(a)
}
}
// ====
// step: rematerialiser
// ----
// {
// let b := 0
// for {
// let a := caller()
// pop(caller())
// }
// caller()
// {
// pop(caller())
// }
// {
// b := 1
// pop(caller())
// }
// }

25
test/libyul/yulOptimizerTests/rematerialiser/branches_for_declared_in_init2.yul
View File

@ -1,25 +0,0 @@
{
let b := 0
for { let a := caller() pop(a) } lt(a, 0) { pop(a) a := add(a, 3) } {
b := 1 pop(a)
}
}
// ====
// step: rematerialiser
// ----
// {
// let b := 0
// for {
// let a := caller()
// pop(caller())
// }
// lt(a, 0)
// {
// pop(a)
// a := add(a, 3)
// }
// {
// b := 1
// pop(a)
// }
// }

5
test/libyul/yulOptimizerTests/rematerialiser/for_break.yul
View File

@ -1,7 +1,8 @@
{
let a
let b
for {let i := 0} lt(i, 10) {i := add(a, b)} {
let i := 0
for {} lt(i, 10) {i := add(a, b)} {
a := origin()
b := origin()
b := caller()
@ -18,8 +19,8 @@
// {
// let a
// let b
// let i := 0
// for {
// let i := 0
// }
// lt(i, 10)
// {

5
test/libyul/yulOptimizerTests/rematerialiser/for_continue.yul
View File

@ -1,7 +1,8 @@
{
let a
let b
for { let i := 0 }
let i := 0
for { }
lt(i, 10)
{ i := add(a, b) } // `b` is always known to be caller() but `a` may be origin() or caller().
{
@ -20,8 +21,8 @@
// {
// let a
// let b
// let i := 0
// for {
// let i := 0
// }
// lt(i, 10)
// {

5
test/libyul/yulOptimizerTests/rematerialiser/for_continue_2.yul
View File

@ -2,7 +2,8 @@
let a
let b
let c
for { let i := 0 }
let i := 0
for { }
lt(i, 10)
{ i := add(add(a, b), c) } // `b` is always known to be caller() but `a` and `c` may be origin() or caller().
{
@ -26,8 +27,8 @@
// let a
// let b
// let c
// let i := 0
// for {
// let i := 0
// }
// lt(i, 10)
// {

12
test/libyul/yulOptimizerTests/rematerialiser/for_continue_with_assignment_in_post.yul
View File

@ -2,10 +2,10 @@
let a
let b
let c
let i := 0
b := origin()
c := origin()
for {
let i := 0
b := origin()
c := origin()
}
lt(i, 10)
{
@ -30,10 +30,10 @@
// let a
// let b
// let c
// let i := 0
// b := origin()
// c := origin()
// for {
// let i := 0
// b := origin()
// c := origin()
// }
// lt(i, 10)
// {

8
test/libyul/yulOptimizerTests/ssaAndBack/for_loop.yul
View File

@ -1,7 +1,7 @@
{
let a := mload(0)
let b := mload(1)
for {
let a := mload(0)
let b := mload(1)
}
lt(mload(a),mload(b))
{
@ -19,9 +19,9 @@
// step: ssaAndBack
// ----
// {
// let a := mload(0)
// let b := mload(1)
// for {
// let a := mload(0)
// let b := mload(1)
// }
// lt(mload(a), mload(b))
// {

7
test/libyul/yulOptimizerTests/ssaPlusCleanup/control_structures.yul
View File

@ -4,7 +4,8 @@
mstore(to, length)
from := add(from, 0x20)
to := add(to, 0x20)
for { let x := 1 } lt(x, length) { x := add(x, 0x20) } {
let x := 1
for { } lt(x, length) { x := add(x, 0x20) } {
mstore(add(to, x), mload(add(from, x)))
}
}
@ -20,9 +21,9 @@
// mstore(to, length_1)
// let from_2 := add(from, 0x20)
// let to_3 := add(to, 0x20)
// let x_4 := 1
// let x := x_4
// for {
// let x_4 := 1
// let x := x_4
// }
// lt(x, length_1)
// {