[PATCH] D41477: [LLD] [ELF] Result of subtracting two symbols should be absolute

[Rafael Avila de Espindola via llvm-commits]

It is fine as is. I committed it in r321390.

Cheers,
Rafael

Erick Reyes <erickreyes at google.com> writes:

> Should I add more test cases?
>
> I don't have commit access.
>
> Thanks
> Erick
>
> On Fri, Dec 22, 2017 at 11:23 AM, Rafael Avila de Espindola <
> rafael.espindola at gmail.com> wrote:
>
>> LGTM.
>>
>> It is not clear that this will work in all cases when the symbols are in
>> different sections but is is an improvement.
>>
>> Do you have commit access?
>>
>> Cheers,
>> Rafael
>>
>> Erick Reyes via Phabricator via llvm-commits
>> <llvm-commits at lists.llvm.org> writes:
>>
>> > erickreyes created this revision.
>> > erickreyes added a reviewer: lld.
>> > erickreyes added a project: lld.
>> > Herald added subscribers: llvm-commits, emaste.
>> >
>> > When two linker script symbols are subtracted, the result should be
>> absolute.
>> >
>> > This is the behavior of binutils' ld.
>> >
>> >
>> > Repository:
>> >   rLLD LLVM Linker
>> >
>> > https://reviews.llvm.org/D41477
>> >
>> > Files:
>> >   ELF/ScriptParser.cpp
>> >   test/ELF/linkerscript/operators.s
>> >
>> >
>> > Index: test/ELF/linkerscript/operators.s
>> > ===================================================================
>> > --- test/ELF/linkerscript/operators.s
>> > +++ test/ELF/linkerscript/operators.s
>> > @@ -1,6 +1,7 @@
>> >  # REQUIRES: x86
>> >  # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
>> >  # RUN: echo "SECTIONS { \
>> > +# RUN:  _start = .; \
>> >  # RUN:  plus = 1 + 2 + 3; \
>> >  # RUN:  minus = 5 - 1; \
>> >  # RUN:  div = 6 / 2; \
>> > @@ -26,6 +27,9 @@
>> >  # RUN:  . = 0xfff0; \
>> >  # RUN:  datasegmentalign = DATA_SEGMENT_ALIGN (0xffff, 0); \
>> >  # RUN:  datasegmentalign2 = DATA_SEGMENT_ALIGN (0, 0); \
>> > +# RUN:  _end = .; \
>> > +# RUN:  minus_rel = _end - 0x10; \
>> > +# RUN:  minus_abs = _end - _start; \
>> >  # RUN: }" > %t.script
>> >  # RUN: ld.lld %t --script %t.script -o %t2
>> >  # RUN: llvm-objdump -t %t2 | FileCheck %s
>> > @@ -53,6 +57,8 @@
>> >  # CHECK: 00000000001000 *ABS* 00000000 commonpagesize
>> >  # CHECK: 0000000000ffff *ABS* 00000000 datasegmentalign
>> >  # CHECK: 0000000000fff0 *ABS* 00000000 datasegmentalign2
>> > +# CHECK: 0000000000ffe0 .text 00000000 minus_rel
>> > +# CHECK: 0000000000fff0 *ABS* 00000000 minus_abs
>> >
>> >  ## Mailformed number error.
>> >  # RUN: echo "SECTIONS { . = 0x12Q41; }" > %t.script
>> > Index: ELF/ScriptParser.cpp
>> > ===================================================================
>> > --- ELF/ScriptParser.cpp
>> > +++ ELF/ScriptParser.cpp
>> > @@ -151,6 +151,8 @@
>> >  }
>> >
>> >  static ExprValue sub(ExprValue A, ExprValue B) {
>> > +  if (!A.isAbsolute() && !B.isAbsolute())
>> > +    return A.getValue() - B.getValue();
>> >    return {A.Sec, false, A.getSectionOffset() - B.getValue(), A.Loc};
>> >  }
>> >
>> >
>> >
>> > Index: test/ELF/linkerscript/operators.s
>> > ===================================================================
>> > --- test/ELF/linkerscript/operators.s
>> > +++ test/ELF/linkerscript/operators.s
>> > @@ -1,6 +1,7 @@
>> >  # REQUIRES: x86
>> >  # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
>> >  # RUN: echo "SECTIONS { \
>> > +# RUN:  _start = .; \
>> >  # RUN:  plus = 1 + 2 + 3; \
>> >  # RUN:  minus = 5 - 1; \
>> >  # RUN:  div = 6 / 2; \
>> > @@ -26,6 +27,9 @@
>> >  # RUN:  . = 0xfff0; \
>> >  # RUN:  datasegmentalign = DATA_SEGMENT_ALIGN (0xffff, 0); \
>> >  # RUN:  datasegmentalign2 = DATA_SEGMENT_ALIGN (0, 0); \
>> > +# RUN:  _end = .; \
>> > +# RUN:  minus_rel = _end - 0x10; \
>> > +# RUN:  minus_abs = _end - _start; \
>> >  # RUN: }" > %t.script
>> >  # RUN: ld.lld %t --script %t.script -o %t2
>> >  # RUN: llvm-objdump -t %t2 | FileCheck %s
>> > @@ -53,6 +57,8 @@
>> >  # CHECK: 00000000001000 *ABS* 00000000 commonpagesize
>> >  # CHECK: 0000000000ffff *ABS* 00000000 datasegmentalign
>> >  # CHECK: 0000000000fff0 *ABS* 00000000 datasegmentalign2
>> > +# CHECK: 0000000000ffe0 .text 00000000 minus_rel
>> > +# CHECK: 0000000000fff0 *ABS* 00000000 minus_abs
>> >
>> >  ## Mailformed number error.
>> >  # RUN: echo "SECTIONS { . = 0x12Q41; }" > %t.script
>> > Index: ELF/ScriptParser.cpp
>> > ===================================================================
>> > --- ELF/ScriptParser.cpp
>> > +++ ELF/ScriptParser.cpp
>> > @@ -151,6 +151,8 @@
>> >  }
>> >
>> >  static ExprValue sub(ExprValue A, ExprValue B) {
>> > +  if (!A.isAbsolute() && !B.isAbsolute())
>> > +    return A.getValue() - B.getValue();
>> >    return {A.Sec, false, A.getSectionOffset() - B.getValue(), A.Loc};
>> >  }
>> >
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