feat: widemul128 hint

[greged93]

This PR adds the widemul128 hint to the hint list. Tests are provided.
Resolves #37.

[rodrigo-pino]

Great! Thanks for your contribution, some small changes and it is ready for approval!

[rodrigo-pino]

@greged93 I believe this library I mentioned on #67 (comment) can be of use. I think it will help make the operations faster leaving only the cost of converting to montgomery form at the end.

[greged93]

Updated @rodrigo-pino!

[omerfirmak]

pkg/hintrunner/hint.go:106:7: leaking param: hint
pkg/hintrunner/hint.go:106:32: leaking param: vm
pkg/hintrunner/hint.go:109:2: moved to heap: lhs
pkg/hintrunner/hint.go:114:2: moved to heap: rhs
pkg/hintrunner/hint.go:152:2: moved to heap: mvLow
pkg/hintrunner/hint.go:162:2: moved to heap: mvHigh
pkg/hintrunner/hint.go:144:29: moved to heap: uint256.words
pkg/hintrunner/hint.go:146:31: moved to heap: uint256.words
pkg/hintrunner/hint.go:107:28: &fp.Element{...} does not escape
pkg/hintrunner/hint.go:111:20: ... argument does not escape
pkg/hintrunner/hint.go:116:20: ... argument does not escape
pkg/hintrunner/hint.go:124:20: ... argument does not escape
pkg/hintrunner/hint.go:132:20: ... argument does not escape
pkg/hintrunner/hint.go:135:23: &uint256.Int{} does not escape
pkg/hintrunner/hint.go:135:76: []big.Word{...} escapes to heap
pkg/hintrunner/hint.go:135:76: &big.Int{...} does not escape
pkg/hintrunner/hint.go:135:50: &uint256.Int{} does not escape
pkg/hintrunner/hint.go:135:50: "overflow" escapes to heap
pkg/hintrunner/hint.go:135:128: []big.Word{...} escapes to heap
pkg/hintrunner/hint.go:135:128: &big.Int{...} does not escape
pkg/hintrunner/hint.go:135:102: &uint256.Int{} does not escape
pkg/hintrunner/hint.go:135:102: "overflow" escapes to heap
pkg/hintrunner/hint.go:138:23: &uint256.Int{} does not escape
pkg/hintrunner/hint.go:139:24: &uint256.Int{} does not escape
pkg/hintrunner/hint.go:143:13: &fp.Element{} does not escape
pkg/hintrunner/hint.go:144:29: new(big.Int) does not escape
pkg/hintrunner/hint.go:145:14: &fp.Element{} does not escape
pkg/hintrunner/hint.go:146:31: new(big.Int) does not escape
pkg/hintrunner/hint.go:150:20: ... argument does not escape
pkg/hintrunner/hint.go:155:20: ... argument does not escape
pkg/hintrunner/hint.go:160:20: ... argument does not escape
pkg/hintrunner/hint.go:165:20: ... argument does not escape

There are multiple GC allocations here. func (hint WideMul128) Execute could be allocation free AFAICS.

[rodrigo-pino]

There are multiple GC allocations here. func (hint WideMul128) Execute could be allocation free AFAICS.

I've been analizing this. lhs and rhs escapes because their FieldElement() and MemoryAddress() methods return pointers instead of the value. I made a local change that fixed it. So that is smth that we should fix on our side. Let me look at the other heap allocations

[rodrigo-pino]

mvHigh and mvLow I am not sure. They shouldn't imo. But that part is on our side as well I because it is not used in the code, so I think it is good to merge once the comment is resolved and fix that later since changes required modifications on other parts of the code. @omerfirmak tell me what you think

[omerfirmak]

lhs and rhs escapes because their FieldElement() and MemoryAddress() methods return pointers instead of the value.

That doesnt seem right to me, we have this pattern everywhere and it doesnt cause heap allocations elsewhere.

I am more suspicious of the interfaces that are in operand.go.