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

[Erick Reyes via llvm-commits]

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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> > llvm-commits at lists.llvm.org
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>
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