similar to: Dropping COMDAT with LTO

Thanks, David and Peter. Some responses to Peter's email below. Teresa On Fri, Jan 13, 2017 at 3:21 PM, Peter Collingbourne <peter at pcc.me.uk> wrote: > Hi Teresa, > > I think that to answer your question correctly it is helpful to consider > what is going on at the object file level. For your test1.c we conceptually > have a .text section containing the body of f, and

On Tue, Jan 17, 2017 at 7:24 PM, Rafael Avila de Espindola < rafael.espindola at gmail.com> wrote: > Teresa Johnson via llvm-dev <llvm-dev at lists.llvm.org> writes: > > > I was wondering though what happens if we have an alias, which may or may > > not be weak itself, to a non-odr weak symbol that isn't prevailing. In > that > > case, do we eventually

Hi Mehdi, Peter and David (and anyone else who sees this), I've been playing with some examples to handle the weak symbol cases we discussed in IRC earlier this week in the context of D28523. I was going to implement the support for turning aliases into copies in order to enable performing thinLTOResolveWeakForLinkerGUID on both aliases and aliasees, as a first step to being able to drop

Hi, I believe we should get it right (and simpler) if (when…) we move to the representation we discussed last spring: https://llvm.org/bugs/show_bug.cgi?id=27866 <https://llvm.org/bugs/show_bug.cgi?id=27866> Our conclusion was that we should always have alias pointing to private anonymous and nothing else, so when we currently have: @a = global i32 0 @b = alias @a It should always

> On Jan 14, 2017, at 8:14 AM, Teresa Johnson <tejohnson at google.com> wrote: > > > > On Fri, Jan 13, 2017 at 9:54 PM, Mehdi Amini <mehdi.amini at apple.com <mailto:mehdi.amini at apple.com>> wrote: > Hi, > > I believe we should get it right (and simpler) if (when…) we move to the representation we discussed last spring:

> On Jan 18, 2017, at 7:11 AM, Teresa Johnson <tejohnson at google.com> wrote: > > > >> On Sat, Jan 14, 2017 at 12:15 PM, Mehdi Amini <mehdi.amini at apple.com> wrote: >> >>> On Jan 14, 2017, at 8:14 AM, Teresa Johnson <tejohnson at google.com> wrote: >>> >>> >>> >>> On Fri, Jan 13, 2017 at 9:54 PM, Mehdi

The problem is that ThinLTO is not dropping the non-prevailing definitions, and they end up being emitted into the object file for b.o. $ ../ra/bin/llvm-dis -o - b.o0.0.preopt.bc | grep __llvm_prof $__llvm_profile_raw_version = comdat any $__llvm_profile_filename = comdat any @__llvm_profile_raw_version = constant i64 72057594037927940, comdat @__llvm_profile_filename = constant [19 x i8]

Thanks Peter, your patch does fix the reproducer. I filed https://bugs.llvm.org/show_bug.cgi?id=37422 to track this bug. I have no clue on how to resolve the tests - whether further cleanup is required in the code or in the tests. But if Teresa or you cannot get to it, I can, with some help, take a crack at fixing the tests. On Wed, May 9, 2018 at 11:26 AM Peter Collingbourne <peter at

Adding Peter to comment on the linker resolution issue. >From adding save-temps, it looks like lld and gold are giving different resolutions to the symbols, which is presumably creating this issue: (first file is with lld and second is with gold) $ diff a.out.resolution.txt gold/ 4c4 < -r=a.o,__llvm_profile_raw_version,plx --- > -r=a.o,__llvm_profile_raw_version,l 8,9c8,9 <

Hi All, This week I've been focused on removing some of the blockers for people transitioning from ORCv1 to ORCv2. Issue #1 (http://llvm.org/PR40074, http://llvm.org/PR44337): When LLVM codegens floating point constants for COFF we produce named constant pool entries of the form __real@<bitval>. These are stored in COFF COMDAT sections [1] which allow duplicate symbol definitions to

Given the following C++ code: ``` // test.cpp struct Foo { int public_foo(); int outside_foo(); [[gnu::always_inline]] int inline_foo() { int x = outside_foo(); if (x % 17) { x += 1; } return x; } [[gnu::noinline]] int inline_bar1() { int x = inline_foo(); if (x % 23) { x += 2; } return x; } [[gnu::noinline]] int inline_bar2() {

On Mon, May 1, 2017 at 11:06 AM, Mehdi AMINI <joker.eph at gmail.com> wrote: > > > 2017-04-25 12:11 GMT-07:00 Peter Collingbourne <peter at pcc.me.uk>: > >> Hi all, >> >> I've been making a number of changes to the summary representation >> recently, and I wanted to lay out some of my plans so that folks are aware >> of my ultimate

On Wed, Jan 18, 2017 at 7:16 AM, Rafael Avila de Espindola < rafael.espindola at gmail.com> wrote: > >> The rule should be that the alias to aliasee link is never broken. The > >> reason being that an alias at the file level is just another symbol with > >> the same value. > >> > >> So if foo is an alias to bar, accessing that foo will always be

On Nov 9, 2011, at 11:34 AM, Rafael Espíndola wrote: >>> 1) [Requires ABI change] We emit dynamic initialization code for weak globals >>> (even in TUs where static initialization is required to be performed), unless >>> we can prove that every translation unit will use static initialization. We >>> emit the global plus its guard variable as a single object so

On Nov 21, 2011, at 9:05 AM, Rafael Espíndola wrote: >> Unfortunately, making the comdat be for the entire function is not >> conformant with the ABI, which says that you either put the variable >> and its guard in different comdats or you put them in a single comdat >> named for the variable. It also doesn't actually help unless we disable >> inlining. >

> I see. Using two comdats would still cause the same problem for us, > no? So the solution in the end is to emit: > > TU1: > -------------------------------- > @_ZN1UI1SE1kE = weak_odr constant i32 42, align 4, comdat _ZN1UI1SE1kE > @_ZGVN1UI1SE1kE = weak_odr global i64 1, comdat _ZN1UI1SE1kE > -------------------------------- > > TU2: >

> Unfortunately, making the comdat be for the entire function is not > conformant with the ABI, which says that you either put the variable > and its guard in different comdats or you put them in a single comdat > named for the variable.  It also doesn't actually help unless we disable > inlining. I see. Using two comdats would still cause the same problem for us, no? So the

>> 1) [Requires ABI change] We emit dynamic initialization code for weak globals >> (even in TUs where static initialization is required to be performed), unless >> we can prove that every translation unit will use static initialization. We >> emit the global plus its guard variable as a single object so the linker can't >> separate them (this is the ABI change).

On Dec 19, 2012, at 4:53 PM, Michael Spencer wrote: > On Wed, Dec 19, 2012 at 4:43 PM, Nick Kledzik <kledzik at apple.com> wrote: >> >> On Dec 19, 2012, at 4:25 PM, Michael Spencer wrote: >>> So I was looking into handling ELF groups today in the Atom model. It >>> appears that we will need to add the concept of a group to the atom >>> model

I support Nick's option too. I think handling groups is another example of using follow on references. One question is how does an atom outside the group refer to the main atom here ? Will not garbage collection cleanup the main atom/signature atom because there are no references ? Thanks - Shankar Easwaran On Wed, Dec 19, 2012 at 5:00 PM, Nick Kledzik <kledzik at apple.com> wrote: