Bug 152186

Summary:

B3::reduceStrength should simplify Div(value, 1 << const)

Product:

WebKit

Reporter:

Filip Pizlo <fpizlo>

Component:

JavaScriptCore

Assignee:

Robin Morisset <rmorisset>

Status:

ASSIGNED ---

Severity:

Normal

CC:

ews-watchlist, keith_miller, mark.lam, msaboff, rmorisset, saam

Priority:

Version:

WebKit Nightly Build

Hardware:

All

OS:

All

See Also:

https://bugs.webkit.org/show_bug.cgi?id=196370

Bug Depends on:

Bug Blocks:

154319, 196361

Attachments:

Description	Flags
Patch	rmorisset: review-, ews-watchlist: commit-queue-

Description Filip Pizlo 2015-12-11 13:34:17 PST

asm.js needs this.

Comment 1 Robin Morisset 2019-03-28 14:47:05 PDT

Created attachment 366211 [details]
Patch

Comment 2 EWS Watchlist 2019-03-28 17:28:54 PDT

Comment on attachment 366211 [details]
Patch

Attachment 366211 [details] did not pass jsc-ews (mac):
Output: https://webkit-queues.webkit.org/results/11695667

New failing tests:
microbenchmarks/integer-modulo.js.ftl-eager
jsc-layout-tests.yaml/js/script-tests/integer-division-neg2tothe32-by-neg1.js.layout-ftl-eager-no-cjit
microbenchmarks/integer-modulo.js.ftl-eager-no-cjit
microbenchmarks/integer-modulo.js.ftl-no-cjit-no-inline-validate
microbenchmarks/integer-modulo.js.ftl-no-cjit-no-put-stack-validate
stress/op_mod-VarConst.js.misc-ftl-no-cjit
microbenchmarks/integer-modulo.js.ftl-no-cjit-validate-sampling-profiler

Comment 3 Robin Morisset 2019-03-29 16:07:48 PDT

I think I found the bug: I assumed that Div was rounding towards -Infinity, but it appears to round towards 0 (or x % y would not be equal to x - (x / y ) * y).
I am not entirely sure how to fix it right now.