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Differential D25855

[lld] Optimize undefined weak symbols in LTO link.
Needs ReviewPublic

Authored by eugenis on Oct 20 2016, 5:27 PM.

Details

Reviewers
ruiu
pcc
Summary

This is the LLD side of D25854

Diff Detail

Repository
rL LLVM

Event Timeline

eugenis updated this revision to Diff 75377.Oct 20 2016, 5:27 PM
eugenis retitled this revision from to [lld] Optimize undefined weak symbols in LTO link..
eugenis updated this object.
eugenis added reviewers: pcc, ruiu.
eugenis set the repository for this revision to rL LLVM.
eugenis added a subscriber: llvm-commits.
Herald added a subscriber: mehdi_amini. · View Herald TranscriptOct 20 2016, 5:27 PM
eugenis updated this revision to Diff 75380.Oct 20 2016, 5:32 PM
eugenis added inline comments.
ELF/LTO.cpp
115 ↗(On Diff #75380)

I'm not sure this condition is correct. isUndefined() is true for non-prevailing definitions, which I try to avoid.

Revision Contents

PathSize
test/
ELF/
lto/
Inputs/
6 lines
19 lines

Diff 75377

test/ELF/lto/Inputs/extern_weak.ll

  • This file was added.
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
define void @bar() {
ret void
}

test/ELF/lto/extern_weak.ll

  • This file was added.
; REQUIRES: x86
; RUN: llvm-as %s -o %t1.o
; RUN: llvm-as %S/Inputs/extern_weak.ll -o %t2.o
; RUN: ld.lld -m elf_x86_64 %t1.o %t2.o -o %t -shared -save-temps
; RUN: llvm-dis %t.0.4.opt.bc -o - | FileCheck %s --check-prefix=DEF
; RUN: ld.lld -m elf_x86_64 %t1.o -o %t -shared -save-temps
; RUN: llvm-dis %t.0.4.opt.bc -o - | FileCheck %s --check-prefix=UNDEF
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
declare extern_weak void @bar()
define i32 @foo() {
ret i32 select (i1 icmp ne (void ()* @bar, void ()* null), i32 1, i32 2)
}
; DEF: ret i32 1
; UNDEF: ret i32 2