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tycho (Steven Noonan)
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User Since
Sep 29 2013, 1:48 AM (487 w, 3 d)

Recent Activity

Jan 16 2020

tycho added a comment to D72682: Avoid creating an immutable map in the Automaton class..

This change is causing test regressions, e.g::

Jan 16 2020, 11:13 PM · Restricted Project

Jan 15 2020

tycho added a comment to D52193: RFC: [clang] Multithreaded compilation support -- NOT FOR SUBMIT.

I did some local work to make this build and pass almost all tests on Linux as well, not to make use of the multi-process features but just to avoid having a separate "for Windows only" branch, and to ensure tests pass across platforms. Unfortunately my change is not at all acceptable for inclusion because it's extremely Linux-specific, and Unix/Program.inc very explicitly says "only use generic UNIX code here". I use pidfds and a timerfd combined with epoll_wait to implement sys::WaitMany. It works well, but I'd be concerned about how to implement this as smoothly for any other *nix platform. pidfd/timerfd/epoll made it downright easy, but I started off trying to look at options that would work more universally on e.g. Linux *and* the BSDs, but I couldn't find anything that wouldn't require building a Rube-Goldberg machine juggling timers, alarms, signals, etc, etc.

Jan 15 2020, 6:24 PM · Restricted Project, Restricted Project

Jan 14 2020

tycho updated subscribers of D72404: [ThinLTO/FullLTO] Support Os and Oz.

Unit tests: fail. 61858 tests passed, 1 failed and 781 were skipped.

failed: Clang.CodeGen/thinlto-debug-pm.c
Jan 14 2020, 1:58 PM · Restricted Project, Restricted Project

Sep 13 2019

tycho added a comment to D52193: RFC: [clang] Multithreaded compilation support -- NOT FOR SUBMIT.

OK, those two problems were actually easy enough to fix.

Sep 13 2019, 8:46 PM · Restricted Project, Restricted Project
tycho added a comment to D52193: RFC: [clang] Multithreaded compilation support -- NOT FOR SUBMIT.

I rebased this myself on the release_90 branch and I was pleasantly surprised that I got the merge right on the first try (?!), and it actually works well without any significant changes (other than merge conflict resolutions).

Sep 13 2019, 8:27 PM · Restricted Project, Restricted Project

Aug 6 2019

tycho added a comment to D63976: Allow clang -Os and -Oz to work with -flto and lld.

OK, that makes sense. So this change would not enforce -O2/-O3 for the bitcode emission, but would enforce one of the two for the LTO phase.

Aug 6 2019, 11:17 AM · Restricted Project
tycho added a comment to D63976: Allow clang -Os and -Oz to work with -flto and lld.

Two things:

Aug 6 2019, 7:26 AM · Restricted Project

Apr 26 2019

tycho accepted D61193: vs integration: Use llvm-lib for librarian.

Also this maybe an independent change, but:

Apr 26 2019, 10:24 AM · Restricted Project

Sep 21 2018

tycho accepted D52343: [llvm-exegesis] Fix PR39021..
Sep 21 2018, 5:35 AM

May 9 2016

tycho added a comment to D17289: [X86] Fix False Data Dependency in popcnt.

Our plan is to first fix the register allocator to bias register assignment choices to hide false dependences. If there is a true dependence on the destination register, then there is no additional cost for the false dependence. So, for example, we will strive to generate

popcnt %rax, %rax
popcnt (%rcx), %rcx

rather than

xor %rdx, %rdx
popcnt %rax, %rdx
xor %rbx, %rbx
popcnt (%rcx), %rbx
May 9 2016, 11:34 AM

May 1 2016

tycho requested changes to D17289: [X86] Fix False Data Dependency in popcnt.

Also I just tested the current patch revision. There's an error in how it is checking whether the destination register is used as the input. The input of popcnt can be a memory location, and the destination register may be part of the address calculation:

May 1 2016, 10:47 AM
tycho added a comment to D17289: [X86] Fix False Data Dependency in popcnt.

Sorry to gravedig, but this hasn't been updated in months. Has this been worked on at all recently?

May 1 2016, 10:05 AM