[LLD][ELF] - Disambiguate "=fillexp" with a primary expression to allow =0x90 /DISCARD/

Fixes https://bugs.llvm.org/show_bug.cgi?id=44903

It is about the following case:

```
SECTIONS {
.foo : {

[LLD][ELF] - Disambiguate "=fillexp" with a primary expression to allow =0x90 /DISCARD/

Fixes https://bugs.llvm.org/show_bug.cgi?id=44903

It is about the following case:

```
SECTIONS {
.foo : { *(.foo) } =0x90909090
/DISCARD/ : { *(.bar) }
}
```

Here while parsing the fill expression we treated the
"/" of "/DISCARD/" as operator.

With this change, suggested by Fangrui Song, we do
not allow expressions with operators (e.g. "0x1100 + 0x22")
that are not wrapped into round brackets. It should not
be an issue for users, but helps to resolve parsing ambiguity.

Differential revision: https://reviews.llvm.org/D74687

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[test] lld/test/: change llvm-objdump single-dash long options to double-dash options

[ELF][test] Change -o %t to -o /dev/null if the output is not needed

[LLD][ELF] - Linkerscript: fix FILL() expressions handling.

D64130 introduced a bug described in the following message:
https://reviews.llvm.org/D64130#1571560

The problem can happen with the follo

[LLD][ELF] - Linkerscript: fix FILL() expressions handling.

D64130 introduced a bug described in the following message:
https://reviews.llvm.org/D64130#1571560

The problem can happen with the following script:

SECTIONS {
.out : {
...
FILL(0x10101010)
*(.aaa)
...
}

The current code tries to read (0x10101010) as an expression and
does not break when meets *, what results in a script parsing error.

In this patch, I verify that FILL command's expression always wrapped in ().
And at the same time =<fillexp> expression can be both wrapped or unwrapped.
I checked it matches to bfd/gold.

Differential revision: https://reviews.llvm.org/D64476

llvm-svn: 365635

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[LLD][ELF] - Linkerscript: add a support for expressions for section's filling

Imagine the script:

.section: {
...
} = FILL_EXPR
LLD assumes that FILL_EXPR is a number, and does not allow
it to be

[LLD][ELF] - Linkerscript: add a support for expressions for section's filling

Imagine the script:

.section: {
...
} = FILL_EXPR
LLD assumes that FILL_EXPR is a number, and does not allow
it to be an expression. Though that is allowed by specification:
https://sourceware.org/binutils/docs-2.32/ld/Output-Section-Fill.html

This patch adds a support for cases when FILL_EXPR is simple math expression.

Fixes https://bugs.llvm.org/show_bug.cgi?id=42482.

Differential revision: https://reviews.llvm.org/D64130

llvm-svn: 365143

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[ELF] Recommit r299635 to pad x86 executable sections with 0xcc

This follows r299748 which fixed a latent bug the original commit exposed.

llvm-svn: 299755

Revert r299635 because it exposed a latent bug.

llvm-svn: 299655

[ELF] Pad x86 executable sections with 0xcc int3 instructions

Executable sections should not be padded with zero by default. On some
architectures, 0x00 is the start of a valid instruction sequence,

[ELF] Pad x86 executable sections with 0xcc int3 instructions

Executable sections should not be padded with zero by default. On some
architectures, 0x00 is the start of a valid instruction sequence, so can confuse
disassembly between InputSections (and indeed the start of the next InputSection
in some situations). Further, in the case of misjumps into padding, padding may
start to be executed silently.

On x86, the "0xcc" byte represents the int3 trap instruction. It is a single
byte long so can serve well as padding. This change switches x86 (and x86_64) to
use this value for padding in executable sections, if no linker script directive
overrides it. It also puts the behaviour into place making it easy to change the
behaviour of other targets when desired. I do not know the relevant instruction
sequences for trap instructions on other targets however, so somebody should add
this separately.

Because the old behaviour simply wrote padding in the whole section before
overwriting most of it, this change also modifies the padding algorithm to write
padding only where needed. This in turn has caused a small behaviour change with
regards to what values are written via Fill commands in linker scripts, bringing
it into line with ld.bfd. The fill value is now written starting from the end of
the previous block, which means that it always starts from the first byte of the
fill, whereas the old behaviour meant that the padding sometimes started mid-way
through the fill value. See the test changes for more details.

Reviewed by: ruiu

Differential Revision: https://reviews.llvm.org/D30886

Bugzilla: http://bugs.llvm.org/show_bug.cgi?id=32227
llvm-svn: 299635

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[ELF] - Support optional comma after output section command.

I found this when tried to link linux kernel with LLD:

https://github.com/torvalds/linux/blob/master/arch/x86/entry/vdso/vdso-layout.lds

[ELF] - Support optional comma after output section command.

I found this when tried to link linux kernel with LLD:

https://github.com/torvalds/linux/blob/master/arch/x86/entry/vdso/vdso-layout.lds.S#L86

Output section command can have optional comma at the end:

.text : { *(.text*) } :text =0x90909090,

It was documented about 3 years ago for binutils:
https://sourceware.org/ml/binutils/2014-04/msg00045.html

Differential revision: https://reviews.llvm.org/D28803

llvm-svn: 292225

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[ELF] - Linkerscript: accept space between '=' and expression in section filler.

Previously we failed to parse next scripts because disallowed
a space between filler value and '=':

.text : {
...

[ELF] - Linkerscript: accept space between '=' and expression in section filler.

Previously we failed to parse next scripts because disallowed
a space between filler value and '=':

.text : {
...
} :text = 0x9090

Differential revision: https://reviews.llvm.org/D24831

llvm-svn: 282248

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Make tests less dependent on the exact layout.

In most cases that means just not checking the address when we don't
need it.

For some tests it is easier to just set . to a known value.

llvm-svn: 2

Make tests less dependent on the exact layout.

In most cases that means just not checking the address when we don't
need it.

For some tests it is easier to just set . to a known value.

llvm-svn: 281976

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[ELF] - Linkerscript: implemented FILL command as alias for =fillexpr

Patch implements FILL just as alias for =fillexpr.
This allows to make implementation much shorted and simpler than D24186.

Di

[ELF] - Linkerscript: implemented FILL command as alias for =fillexpr

Patch implements FILL just as alias for =fillexpr.
This allows to make implementation much shorted and simpler than D24186.

Differential revision: https://reviews.llvm.org/D24227

llvm-svn: 280708

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Remove useless file prefix.

Differential Revision: https://reviews.llvm.org/D24207

llvm-svn: 280540