Compute lazy lambda serialization #7870

RazvanN7 · 2018-02-12T09:08:50Z

This is an optimization to compute the lambda serialization only when __traits(isSame) is used on lambda functions.

dlang-bot · 2018-02-12T09:08:51Z

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stefan-koch-sociomantic · 2018-02-12T13:34:48Z

src/dmd/lambdacomp.d

    {
-        buf.reset();
+        if (LOG)


stefan-koch-sociomantic · 2018-02-12T13:35:05Z

src/dmd/lambdacomp.d

@@ -83,6 +86,8 @@ public:
    override void visit(FuncLiteralDeclaration fld)
    {
        assert(fld.type.ty != Terror);
+        if (LOG)


andralex

cc @WalterBright

JinShil · 2018-02-12T18:39:24Z

There aren't any tests and coverage is only 80%. Is that deliberate?

RazvanN7 · 2018-02-13T09:31:59Z

@JinShil This PR does not introduce any new functionality, but optimizes the lambda comparison. The code is not covered because the struct and class cases are identical and I only added examples for one of them. I will add another few tests so that coverage is 100%.

P.S. : Everything is covered now.

timotheecour · 2018-02-13T10:08:37Z

@RazvanN7 speaking of __traits(isSame) and lambdas, there's a regression in git master:
https://issues.dlang.org/show_bug.cgi?id=18430 Issue 18430 - isSame is wrong for non global lambdas; obviously this PR couldn't have caused it since it's not merged but maybe you'd have some idea? (sorry for the drop in)

EDIT: just found out you already had a fix in progress #7885; thanks!

wilzbach · 2018-02-13T14:09:48Z

src/dmd/lambdacomp.d

@@ -34,6 +35,8 @@ import dmd.statement;
 import dmd.tokens;
 import dmd.visitor;

+enum LOG = false;


Out of interest: why not version= LOG? This is commonly used pattern in DRuntime.

This is the pattern used in dmd from what I could obeserve :

https://github.com/dlang/dmd/blob/master/src/dmd/mtype.d#L61
https://github.com/dlang/dmd/blob/master/src/dmd/expression.d#L67
https://github.com/dlang/dmd/blob/master/src/dmd/expressionsem.d#L73

And the list could continue.

wilzbach · 2018-02-13T14:11:46Z

src/dmd/traits.d

-            import core.stdc.string;
+            const(char)* getSerialization(FuncLiteralDeclaration fld)
+            {
+                import dmd.lambdacomp;


Nit: local imports should be selective.

wilzbach · 2018-02-13T14:13:33Z

src/dmd/traits.d

@@ -1453,8 +1453,24 @@ extern (C++) Expression semanticTraits(TraitsExp e, Scope* sc)

        if (l1 && l2)
        {
-            import core.stdc.string;
+            const(char)* getSerialization(FuncLiteralDeclaration fld)


Why don't you return string here? Comparing D strings is more efficient (no \0 checking)
You already know the length of the buffer - no need to throw this valuable information away.

I know it's easier with strings, but the serialization field is is const(char)* and I really haven't seen AST members declared as strings. All of them are const(char)*

Quoting a conversation with Walter here:

On 12/5/2017 11:20 AM, Andrei Alexandrescu wrote:
Hi Walter, Seb noticed that the dmd code is going through unpleasant hoops caused by C-style strings. Do you think incrementally switching to D-style strings would improve the compiler? -- Andrei

Yes, but we have to be mindful of gdc and ldc both relying on the C++ interface to use dmd, and D strings don't work on that interface.
I've already converted a bunch of internal stuff to D strings where the interface to the back end was not involved.

(we can even convert the C++ interfaces, but that's significantly more effort)

So how do we proceed here? That was my problem also: I may turn the field into a string, but what should I do regarding the header file?

Well, as its a new field and not used by GDC or LDC at the moment, you could do sth. like:

struct DString { size_t length; char* head; }

CC @ibuclaw @redstar @klickverbot

We have to start somewhere, but I don't want to block your PR with this. Sorry.

how about this:

extern(C++) Dstring funLib(Dstring input);

see full working example here showing using such API from C++ with the function defined in D.

https://github.com/timotheecour/dtools/blob/master/tests/d01_dmd_string/

EDIT: see #7893

@timotheecour #7893 is a good step in the right direction, we need to start using D strings in the compiler. That would be an effort separated from this.

RazvanN7 · 2018-02-14T14:23:22Z

I discovered some problems. Please do not merge.

Later edit: I solved the issue. Ready to merge.

andralex · 2018-02-20T18:13:10Z

src/dmd/traits.d

@@ -1453,8 +1453,24 @@ extern (C++) Expression semanticTraits(TraitsExp e, Scope* sc)

        if (l1 && l2)
        {
-            import core.stdc.string;
+            const(char)* getSerialization(FuncLiteralDeclaration fld)


@timotheecour #7893 is a good step in the right direction, we need to start using D strings in the compiler. That would be an effort separated from this.

RazvanN7 force-pushed the Lambda_v2 branch 2 times, most recently from 93eee54 to 5fb1c17 Compare February 12, 2018 09:13

stefan-koch-sociomantic reviewed Feb 12, 2018

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src/dmd/lambdacomp.d Outdated

{

buf.reset();

if (LOG)

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static if

stefan-koch-sociomantic reviewed Feb 12, 2018

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RazvanN7 force-pushed the Lambda_v2 branch from 5fb1c17 to a51aa6c Compare February 12, 2018 13:51

andralex approved these changes Feb 12, 2018

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RazvanN7 force-pushed the Lambda_v2 branch from a51aa6c to 9390ce0 Compare February 13, 2018 09:39

wilzbach reviewed Feb 13, 2018

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RazvanN7 force-pushed the Lambda_v2 branch 2 times, most recently from f788974 to d330e9e Compare February 14, 2018 09:43

RazvanN7 changed the title ~~Compute lazy lambda serialization~~ [WIP]Compute lazy lambda serialization Feb 14, 2018

dlang-bot added the Review:WIP Work In Progress - not ready for review or pulling label Feb 14, 2018

timotheecour mentioned this pull request Feb 14, 2018

[WIP] add extern (C++) struct Darray(T) and Dstring to simplify interop with C++ #7893

Closed

RazvanN7 force-pushed the Lambda_v2 branch from d330e9e to 91c718a Compare February 15, 2018 12:08

RazvanN7 changed the title ~~[WIP]Compute lazy lambda serialization~~ Compute lazy lambda serialization Feb 15, 2018

Compute lazy lambda serialization

badb47e

RazvanN7 force-pushed the Lambda_v2 branch from 91c718a to badb47e Compare February 15, 2018 12:11

andralex approved these changes Feb 20, 2018

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andralex added the Merge:auto-merge label Feb 20, 2018

dlang-bot merged commit 9f0022b into dlang:master Feb 20, 2018

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Compute lazy lambda serialization #7870

Compute lazy lambda serialization #7870

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