The f32.floor test in wasm/float.js computes a NaN rather than 40 as it should when the baseline compiler is run with --no-sse3. (Other tests in that file may fail too in this configuration, haven't checked yet.) This is particularly odd, as the baseline compiler generates a callout for floor always; ABI problem? Only a problem on x86, ie, 32-bit. Looks like it is both optimized and non-optimized builds, both DEBUG and not. Also happens on 32-bit Windows 7 runs. Locally I'm compiling with -mfpmath=sse -msse -msse2, but on try (where I first saw this) I'm using whatever flags are the default, so I don't think that's it. Beats me why we haven't seen this before, maybe --wasm-always-baseline is not used as extensively as we think it should be? Tiering will take care of that...

I guess this blocks tiering, then.

Looking at these try runs, there are additional failures for --no-sse3. https://treeherder.mozilla.org/#/jobs?repo=try&revision=d1a3573aa167d777787c6de97b2acffd5a18b532&selectedJob=106943751 https://treeherder.mozilla.org/#/jobs?repo=try&revision=d1a3573aa167d777787c6de97b2acffd5a18b532&selectedJob=106954494 (I've repro'd the linux results locally on mozilla-inbound c74284491275, my massive patch queue that is underneath those runs is not needed.)

[Tracking Requested - why for this release]: correctness issues in wasm for x86 machines *without* SSE4 support. Bug 1340219 changed the ABI: return paths of floating-point functions don't need to do the x87 FPU dance anymore, under wasm ABI.

owait, we don't need to track: the wasm baseline compiler isn't enabled there.

Comment on attachment 8877611 [details] [diff] [review] fix.patch Review of attachment 8877611 [details] [diff] [review]: ----------------------------------------------------------------- Excellent, thank you.

Pushed by bbouvier@mozilla.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/31758734ff3c wasm baseline: don't read returned values from x87 FPU stack on x86; r=lth

Did you want to request beta uplift on this one, or is this wontfix for 55 because baseline is unused?

The baseline compiler isn't enabled by default in 55 (can be enabled through a pref though). I don't think there's any intent to uplift a patch that would enable the wasm baseline compiler. So we don't need to uplift this patch. Thanks for the heads-up!