SIMD groundwork part 1 #27169

huonw · 2015-07-20T20:20:12Z

This implements rust-lang/rfcs#1199 (except for doing all the platform intrinsics).

Things remaining for SIMD (not necessarily in this PR):

I (@huonw) am signed up to ensure the compiler matches the RFC, when it lands
the platform specific intrinsics aren't properly type checked at the moment (LLVM will throw a "random" assertion)
there's a lot of useful intrinsics that are missing, including whole platforms (mips, powerpc)
the target-feature cfg detection/adding is not so great at the moment
I think the platform specific intrinsics should go in their own extern ABI (i.e. not "rust-intrinsic")

(I'm adjusting the RFC to reflect the latter.)

I think it would be very nice for this to land without requiring the RFC to land first, because of the first point, and because this is the only way for any further work to happen/be experimented with, without requiring people to build/install/multirust a compiler from a custom branch.

r? @alexcrichton

eefriedman · 2015-07-20T21:51:29Z

src/librustc_trans/trans/type_of.rs

-              let llet = in_memory_type_of(cx, t.simd_type(cx.tcx()));
+              let elem_ty = match t.simd_machine_type(cx.tcx()) {
+                  Some(e) => e,
+                  None => cx.sess().fatal("monomorphising SIMD type to an incompatible element")


This is ugly... is allowing generic SIMD types actually important in practice? It seems like you could accomplish most of what is necessary with traits and maybe a few macros.

I agree it isn't so great, but note that in practice type safety is ensured via traits, e.g. struct Simd4<T: SimdElem>(T, T, T, T);.

This is the major difference to our current #[simd] scheme. Being generic is extremely useful, or else there is some extreme code-duplication and the compiler/library can't "synthesize" random types for helpers easily (i.e. forcing that duplication), e.g. fn get_high<T: SimdElem>(Simd4<T>) -> Simd2<T> works with any T but would require manually writing out for every Tx4 concrete type. (It'd be good to keep this sort of "high level" discussion on rust-lang/rfcs#1199 .)

Still not sure this is a great... but okay, I'll move the discussion.

alexcrichton · 2015-07-21T00:11:21Z

src/librustc_driver/target_features.rs

+
+fn features_contain(sess: &Session, s: &str) -> bool {
+    sess.target.target.options.features.contains(s) ||
+        sess.opts.cg.target_feature.contains(s)


Isn't querying LLVM the "most robust" thing to do here? I guess all of these are disabled by default, though?

They're all disabled by default, yeah; and querying LLVM doesn't seem overly possible, unfortunately. You have a better idea about LLVM's structure so maybe you can wrangle something, though.

I believe you can get ahold of a TargetMachineRef, get ahold of the MCSubtargetInfo, get the list of features, and then test for various features being available.

It's probably not super critical that this happens immediately though.

Could you add a comment to this function with the results of this investigation? Basically something along the lines of "we'd love to do X but we couldn't do it because of Y, hence we're doing the 'poor mans' version Z"

alexcrichton · 2015-07-21T00:40:16Z

Nice work @huonw!

I think the platform specific intrinsics should go in their own extern ABI (i.e. not "rust-intrinsic")

I agree, not having the namespace of "simd_" made me a tad uneasy.

I think it would be very nice for this to land without requiring the RFC to land first, because of the first point, and because this is the only way for any further work to happen/be experimented with, without requiring people to build/install/multirust a compiler from a custom branch.

I would personally be ok with this, but I'm curious to hear what others think as well? Also, do you think the RFC basically has "broad consensus" modulo minor details by this point? If there are still some somewhat contentious decisions here and there it may be worth waiting a little longer before landing this, but if we're all in agreement pretty much then any future minor updates can be easily reflected here (as everything is unstable anyway).

cc @rust-lang/lang

bors · 2015-07-22T12:50:54Z

☔ The latest upstream changes (presumably #27176) made this pull request unmergeable. Please resolve the merge conflicts.

bors · 2015-07-31T06:10:03Z

☔ The latest upstream changes (presumably #27382) made this pull request unmergeable. Please resolve the merge conflicts.

huonw · 2015-08-06T22:32:42Z

Ok, rebased and updated to be better, including

intrinsics for casts and arithmetic (i.e. operators don't work automatically for SIMD types: they have to go via the normal traits)
a special platform-intrinsic extern ABI for these intrinsics,
type-checking the platform-specific intrinsics,
some general refactorings

(I'm updating the RFC to ensure it matches the things I've learned while implementing, as we speak.)

Port the SIMD code to rust-lang/rust#27169

bors · 2015-08-07T14:59:36Z

☔ The latest upstream changes (presumably #27551) made this pull request unmergeable. Please resolve the merge conflicts.

Finish porting the SIMD code to rust-lang/rust#27169

alexcrichton · 2015-08-11T18:38:36Z

src/librustc_trans/trans/intrinsic.rs

@@ -897,7 +906,41 @@ pub fn trans_intrinsic_call<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,

        }

-        (_, _) => ccx.sess().span_bug(foreign_item.span, "unknown intrinsic")
+        (_, _) => {
+            match Intrinsic::find(tcx, &name) {


Could this de-indent a level via:

let intr = match ... { None => ccx.sess().span_bug(...), Some(intr) => intr, };

alexcrichton · 2015-08-11T18:55:24Z

Looking good to me! Just a minor nit so far

huonw · 2015-08-13T04:18:34Z

Updated (will rebase in a bit), includes addressing the nit, adding a pile of platform intrinsic definitions (gets much of x86-64 from SSE to AVX2 and ARM NEON), and adding tests.

huonw · 2015-08-13T04:22:05Z

(There's still some more tests I want to add, particularly run-pass tests making sure the various generic intrinsics behave sanely.)

cesarb · 2015-08-13T11:00:44Z

src/librustc_trans/trans/type_of.rs

@@ -223,7 +224,14 @@ pub fn sizing_type_of<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>, t: Ty<'tcx>) -> Typ

        ty::TyStruct(..) => {
            if t.is_simd(cx.tcx()) {
-                let llet = type_of(cx, t.simd_type(cx.tcx()));
+                let e = t.simd_type(cx.tcx());
+                println!("sizing_type_of: simd: {}", e);


This seems to be a stray debugging println!, which is hit while compiling libcore.

Format: fn shuffle_simdNNN<T, U>(x: T, y: T, idx: [u32; NNN]) -> U;

Absolute correctness is checked at monomorphisation time.

Better error messages, US spelling, more real checks.

Overload the operators using the traits so that things mostly keep working during the deprecation period.

I.e. the signature now must be fn simd_shuffleNNN<T, U>(x: T, y: T, idx: [u32; NNN]) -> U; (modulo names.)

Factor out common pieces, follow `expected ..., found ...` convention everywhere.

huonw · 2015-08-17T21:57:40Z

@bors r=alexcrichton

bors · 2015-08-17T21:57:41Z

📌 Commit 02e9734 has been approved by alexcrichton

bors · 2015-08-17T23:41:37Z

⌛ Testing commit 02e9734 with merge e35fd74...

@huonw

This implements rust-lang/rfcs#1199 (except for doing all the platform intrinsics). Things remaining for SIMD (not necessarily in this PR): - [x] I (@huonw) am signed up to ensure the compiler matches the RFC, when it lands - [x] the platform specific intrinsics aren't properly type checked at the moment (LLVM will throw a "random" assertion) - [ ] there's a lot of useful intrinsics that are missing, including whole platforms (mips, powerpc) - [ ] the target-feature `cfg` detection/adding is not so great at the moment - [x] I think the platform specific intrinsics should go in their own `extern` ABI (i.e. not `"rust-intrinsic"`) (I'm adjusting the RFC to reflect the latter.) I think it would be very nice for this to land without requiring the RFC to land first, because of the first point, and because this is the only way for any further work to happen/be experimented with, without requiring people to build/install/multirust a compiler from a custom branch. r? @alexcrichton

bors · 2015-08-18T02:02:55Z

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt, auto-win-gnu-32-nopt-t, auto-win-gnu-32-opt, auto-win-gnu-64-nopt-t, auto-win-gnu-64-opt, auto-win-msvc-32-opt, auto-win-msvc-64-opt

@metajack

Change simd to repr simd & bump version number With [SIMD groundwork part 1](rust-lang/rust#27169) the simd feature is now repr_simd. Bump the version number since this relies on the rust PR. r? @metajack  [<img src="https://reviewable.io/review_button.png" height=40 alt="Review on Reviewable"/>](https://reviewable.io/reviews/servo/euclid/101)

@metajack

Change simd to repr simd & bump version number With [SIMD groundwork part 1](rust-lang/rust#27169) the simd feature is now repr_simd. Bump the version number since this relies on the rust PR. r? @metajack  [<img src="https://reviewable.io/review_button.png" height=40 alt="Review on Reviewable"/>](https://reviewable.io/reviews/servo/euclid/101)

rust-highfive assigned alexcrichton Jul 20, 2015

eefriedman reviewed Jul 20, 2015
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huonw force-pushed the simd branch 2 times, most recently from 68fb467 to 88cdfbd Compare July 20, 2015 22:56

alexcrichton reviewed Jul 21, 2015
View reviewed changes

huonw force-pushed the simd branch from 88cdfbd to 4de6fab Compare July 29, 2015 23:45

huonw force-pushed the simd branch 3 times, most recently from fe76451 to 16c5c37 Compare August 6, 2015 22:29

cesarb added a commit to cesarb/blake2-rfc that referenced this pull request Aug 7, 2015

Port code to "SIMD groundwork part 1"

9e5a416

Port the SIMD code to rust-lang/rust#27169

cesarb mentioned this pull request Aug 7, 2015

SIMD groundwork rust-lang/rfcs#1199

Merged

cesarb added a commit to cesarb/blake2-rfc that referenced this pull request Aug 8, 2015

Finish porting code to "SIMD groundwork part 1"

05b5e01

Finish porting the SIMD code to rust-lang/rust#27169

alexcrichton reviewed Aug 11, 2015
View reviewed changes

alexcrichton mentioned this pull request Aug 12, 2015

Tracking issue for SIMD support #27731

Closed

huonw force-pushed the simd branch from 16c5c37 to b05b2a4 Compare August 13, 2015 04:17

huonw force-pushed the simd branch from b05b2a4 to d3ba568 Compare August 13, 2015 04:19

cesarb reviewed Aug 13, 2015
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huonw added 11 commits August 17, 2015 14:41

Add most AVX intrinsics.

29b79aa

Add most AVX2 intrinsics.

2a408ef

Reorganise ARM intrinsic definitions.

d598bdd

Add most ARM intrinsics.

2115468

Switch shuffle intrinsics to arrays of indices.

1f5739f

Format: fn shuffle_simdNNN<T, U>(x: T, y: T, idx: [u32; NNN]) -> U;

Allow generic repr(simd) types.

8b68f58

Absolute correctness is checked at monomorphisation time.

Fix existing tests for new #[repr(simd)].

3e50067

Tweak intrinsic error handling.

926b835

Better error messages, US spelling, more real checks.

Add tests for various intrinsic behaviours.

84de8ca

Code style tweaks.

4b24249

Rebase cleanup: is_simd lost its parameter.

62ba85b

huonw force-pushed the simd branch from 3d5cb38 to 4c92357 Compare August 17, 2015 21:41

huonw added 5 commits August 17, 2015 14:48

Shim some of the old std::simd functionality.

d792925

Overload the operators using the traits so that things mostly keep working during the deprecation period.

simd_shuffleNNN returns its type parameter directly.

891c914

I.e. the signature now must be fn simd_shuffleNNN<T, U>(x: T, y: T, idx: [u32; NNN]) -> U; (modulo names.)

Revamp SIMD intrinsic trans error handling.

502f9ac

Factor out common pieces, follow `expected ..., found ...` convention everywhere.

Clean up simd_cast translation.

b067e44

Add AArch64 vrecpeq_... intrinsic (necessary for minimal API).

02e9734

huonw force-pushed the simd branch from 4c92357 to 02e9734 Compare August 17, 2015 21:48

huonw mentioned this pull request Aug 18, 2015

ABIs are validated before cfg-ing #27873

Closed

bors merged commit 02e9734 into rust-lang:master Aug 18, 2015

bors mentioned this pull request Aug 18, 2015

Improve handling of immediate values #27600

Closed

bjwbell mentioned this pull request Aug 28, 2015

Change simd to repr simd & bump version number servo/euclid#101

Merged

bjwbell referenced this pull request in bjwbell/servo Aug 29, 2015

Initial SIMD glyph advance_for_char_range

40ae5d3

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SIMD groundwork part 1 #27169

SIMD groundwork part 1 #27169

huonw commented Jul 20, 2015

eefriedman Jul 20, 2015

huonw Jul 20, 2015

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SIMD groundwork part 1 #27169

SIMD groundwork part 1 #27169

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