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Mask generator optimizations #15935

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Mask generator optimizations #15935

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647f72f
Mask generator optimizations
Feb 14, 2025
693d5aa
disable test for EOF
Mar 15, 2025
85adca6
remove runs based heuristic
Mar 17, 2025
dc34c4e
add a semantic test for masks
Mar 25, 2025
1afea11
add unit tests for constant optimizer using solfuzzer
Apr 2, 2025
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2 changes: 1 addition & 1 deletion Changelog.md
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ Language Features:


Compiler Features:

* Constant Optimizer: Compute masks using shifts when optimizing for size.

Bugfixes:
* SMTChecker: Fix incorrect analysis when only a subset of contracts is selected with `--model-checker-contracts`.
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20 changes: 19 additions & 1 deletion libevmasm/ConstantOptimiser.cpp
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@cameel cameel Mar 15, 2025 •
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@ekpyron Not strictly related to the PR, but while looking at it I noticed that ConstantOptimisationMethod::simpleRunGas() does not account for the new AssemblyItem types we introduced for EOF.

Especially DUPN and SWAPN. Though fortunately it should not have any real consequences because we are not using them in constant optimizer yet (heads up @rodiazet).

Original file line number Diff line number Diff line change
Expand Up @@ -253,7 +253,25 @@ AssemblyItems ComputeMethod::findRepresentation(u256 const& _value)
if (_value < 0x10000)
// Very small value, not worth computing
return AssemblyItems{_value};
else if (numberEncodingSize(~_value) < numberEncodingSize(_value))

// check for masks first
unsigned lowZeros = 0;
unsigned highOnes = 0;
for (; ((_value >> lowZeros) & 1) == 0 && lowZeros < 256; lowZeros++) {}
for (; ((_value >> (lowZeros + highOnes)) & 1) == 1 && highOnes < 256; highOnes++) {}
if (m_params.evmVersion.hasBitwiseShifting() && highOnes > 32 &&
((_value >> (lowZeros + highOnes)) == 0) &&
((lowZeros + highOnes < 256) || lowZeros > 16))
{
// this is a big enough mask to use zero negation
AssemblyItems newRoutine = AssemblyItems{u256(0), Instruction::NOT};
if ((highOnes + lowZeros) != 256)
newRoutine += AssemblyItems{u256(256 - highOnes), Instruction::SHR};
if (lowZeros > 0)
newRoutine += AssemblyItems{u256(lowZeros), Instruction::SHL};
return newRoutine;
}
if (numberEncodingSize(~_value) < numberEncodingSize(_value))
// Negated is shorter to represent
return findRepresentation(~_value) + AssemblyItems{Instruction::NOT};
else
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4 changes: 2 additions & 2 deletions test/cmdlineTests/optimizer_BlockDeDuplicator/output
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Expand Up @@ -7,11 +7,11 @@ EVM assembly:
0x00
dup1
sload
not(sub(shl(0x40, 0x01), 0x01))
shl(0x40, not(0x00))
and
/* "optimizer_BlockDeDuplicator/input.sol":201:206 fun_x */
or(tag_0_7, shl(0x20, tag_2))
sub(shl(0x40, 0x01), 0x01)
shr(0xc0, not(0x00))
/* "optimizer_BlockDeDuplicator/input.sol":179:210 function() r = true ? fun_x : f */
and
or
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2 changes: 1 addition & 1 deletion test/cmdlineTests/optimizer_inliner_dynamic_reference/output
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Expand Up @@ -84,7 +84,7 @@ sub_0: assembly {
/* "optimizer_inliner_dynamic_reference/input.sol":147:152 x = f */
dup1
sload
not(0xffffffffffffffff)
shl(0x40, not(0x00))
and
/* "optimizer_inliner_dynamic_reference/input.sol":151:152 f */
tag_17
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4 changes: 2 additions & 2 deletions test/cmdlineTests/optimizer_inliner_dynamic_reference_constructor/output
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Expand Up @@ -17,11 +17,11 @@ tag_1:
/* "optimizer_inliner_dynamic_reference_constructor/input.sol":93:98 x = f */
dup1
sload
not(sub(shl(0x40, 0x01), 0x01))
shl(0x40, not(0x00))
and
/* "optimizer_inliner_dynamic_reference_constructor/input.sol":97:98 f */
or(tag_0_12, shl(0x20, tag_4))
sub(shl(0x40, 0x01), 0x01)
shr(0xc0, not(0x00))
/* "optimizer_inliner_dynamic_reference_constructor/input.sol":93:98 x = f */
and
or
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8 changes: 4 additions & 4 deletions test/cmdlineTests/standard_debug_info_in_evm_asm_via_ir_location/output.json
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Expand Up @@ -20,7 +20,7 @@
dup4
add
swap2
sub(shl(0x40, 0x01), 0x01)
shr(0xc0, not(0x00))
dup4
gt
dup5
Expand Down Expand Up @@ -104,7 +104,7 @@ sub_0: assembly {
jumpi(tag_26, callvalue)
jumpi(tag_26, slt(add(not(0x03), calldatasize), 0x00))
sload(0x00)
sub(shl(0xff, 0x01), 0x01)
shr(0x01, not(0x00))
dup2
eq
tag_14
Expand Down Expand Up @@ -350,7 +350,7 @@ sub_0: assembly {
dup4
add
swap2
sub(shl(0x40, 0x01), 0x01)
shr(0xc0, not(0x00))
dup4
gt
dup5
Expand Down Expand Up @@ -450,7 +450,7 @@ sub_0: assembly {
jumpi(tag_26, callvalue)
jumpi(tag_26, slt(add(not(0x03), calldatasize), 0x00))
sload(0x00)
sub(shl(0xff, 0x01), 0x01)
shr(0x01, not(0x00))
dup2
eq
tag_14
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4 changes: 2 additions & 2 deletions test/cmdlineTests/viair_subobject_optimization/output
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Expand Up @@ -18,7 +18,7 @@ EVM assembly:
dup4
add
swap2
sub(shl(0x40, 0x01), 0x01)
shr(0xc0, not(0x00))
dup4
gt
dup5
Expand Down Expand Up @@ -223,7 +223,7 @@ sub_0: assembly {
dup4
add
swap2
sub(shl(0x40, 0x01), 0x01)
shr(0xc0, not(0x00))
dup4
gt
dup5
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3 changes: 3 additions & 0 deletions test/cmdlineTests/~soljson_via_fuzzer/test.sh
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Expand Up @@ -13,4 +13,7 @@ cd "$SOLTMPDIR"
gnu_grep -L --include="*.sol" "^pragma experimental solidity;$" ./* | xargs -P 4 -n 50 "${SOLIDITY_BUILD_DIR}/test/tools/solfuzzer" --quiet --input-files
gnu_grep -L --include="*.sol" "^pragma experimental solidity;$" ./* | xargs -P 4 -n 50 "${SOLIDITY_BUILD_DIR}/test/tools/solfuzzer" --without-optimizer --quiet --input-files

# constant optimizer tests
grep -v "#" "$REPO_ROOT"/test/libevmasm/constants.txt | xargs -I {} sh -c "echo -n {} | \"${SOLIDITY_BUILD_DIR}\"/test/tools/solfuzzer --quiet --const-opt --hex"

rm -r "$SOLTMPDIR"
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