This patch is extracted from D96035, it adds support for the existing
DWARFLinker functionality. What is not supported yet:

1. Types deduplication(--odr mode).
2. Modules deduplication.
3. Generation of index tables.

Reland2: temporarily disabled call to "--linker llvm" for tls-variable.test
and location-expression.test as it does not work properly on bigendian
architecture.

Differential Revision: https://reviews.llvm.org/D153268

This reverts commit 0229dd0626b2538c78ebbd2b1bd44c31fbf1cdec.

This introduces two test failures on s390x.

tools/dsymutil/X86/location-expression.test:

    warning: cann't load line table.
    note: while processing CU1
    /builddir/build/BUILD/llvm-18.0.0.src/test/tools/dsymutil/X86/location-expression.test:20:10: error: CHECK: expected string not found in input
    # CHECK: DW_AT_name{{.*}}"CU1"
             ^
    <stdin>:34:32: note: scanning from here
    0x0000000b: DW_TAG_compile_unit [1] *
                                   ^
    <stdin>:37:2: note: possible intended match here
     DW_AT_name [DW_FORM_strp] ( .debug_str[0x09000000] = )
     ^

tools/dsymutil/X86/tls-variable.test:

    warning: cann't load line table.
    note: while processing CU1
    /builddir/build/BUILD/llvm-18.0.0.src/test/tools/dsymutil/X86/tls-variable.test:19:10: error: CHECK: expected string not found in input
    # CHECK: DW_AT_name{{.*}}"CU1"
             ^
    <stdin>:26:32: note: scanning from here
    0x0000000b: DW_TAG_compile_unit
                                   ^
    <stdin>:29:2: note: possible intended match here
     DW_AT_name ()
     ^

This patch is extracted from D96035, it adds support for the existing
DWARFLinker functionality. What is not supported yet:

1. Types deduplication(--odr mode).
2. Modules deduplication.
3. Generation of index tables.

Differential Revision: https://reviews.llvm.org/D153268

This reverts commit 1506e4c77624aa3d208658fd356b9caccc1a713f.

This patch is extracted from D96035, it adds support for the existing
DWARFLinker functionality. What is not supported yet:

1. Types deduplication(--odr mode).
2. Modules deduplication.
3. Generation of index tables.

Differential Revision: https://reviews.llvm.org/D153268

This review is extracted from D96035.

This patch adds possibility to keep not only DwarfStringPoolEntry, but also
pointer to it. The DwarfStringPoolEntryRef keeps reference to the string map entry.
String map keeps string data and corresponding DwarfStringPoolEntry
info. Not all string map entries may be included into the result,
and then not all string entries should have DwarfStringPoolEntry
info. Currently StringMap keeps DwarfStringPoolEntry for all entries.
It leads to extra memory usage. This patch allows to keep
DwarfStringPoolEntry info only for entries which really need it.

[reland] : make msan happy.

Reviewed By: JDevlieghere

Differential Revision: https://reviews.llvm.org/D126883

Breaks msan bot, see D126883

This reverts commit 77df3be0dee415713cf5c79543f00532674f428b.

This review is extracted from D96035.

This patch adds possibility to keep not only DwarfStringPoolEntry, but also
pointer to it. The DwarfStringPoolEntryRef keeps reference to the string map entry.
String map keeps string data and corresponding DwarfStringPoolEntry
info. Not all string map entries may be included into the result,
and then not all string entries should have DwarfStringPoolEntry
info. Currently StringMap keeps DwarfStringPoolEntry for all entries.
It leads to extra memory usage. This patch allows to keep
DwarfStringPoolEntry info only for entries which really need it.

Reviewed By: JDevlieghere

Differential Revision: https://reviews.llvm.org/D126883