Merge llvm-project main llvmorg-18-init-18359-g93248729cfae

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-18-init-18359-g93248729cfae, t

Merge llvm-project main llvmorg-18-init-18359-g93248729cfae

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-18-init-18359-g93248729cfae, the
last commit before the upstream release/18.x branch was created.

PR: 276104
MFC after: 1 month

(cherry picked from commit 7a6dacaca14b62ca4b74406814becb87a3fefac0)

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Merge llvm-project main llvmorg-18-init-16595-g7c00a5be5cde

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-18-init-16595-g7c00a5be5cde.

Merge llvm-project main llvmorg-18-init-16595-g7c00a5be5cde

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-18-init-16595-g7c00a5be5cde.

PR: 276104
MFC after: 1 month

(cherry picked from commit 1db9f3b21e39176dd5b67cf8ac378633b172463e)

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Merge llvm-project main llvmorg-18-init-15088-gd14ee76181fb

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-18-init-15088-gd14ee76181fb.

Merge llvm-project main llvmorg-18-init-15088-gd14ee76181fb

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-18-init-15088-gd14ee76181fb.

PR: 276104
MFC after: 1 month

(cherry picked from commit 5f757f3ff9144b609b3c433dfd370cc6bdc191ad)

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Merge llvm-project main llvmorg-17-init-19304-gd0b54bb50e51

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-17-init-19304-gd0b54bb50e51, t

Merge llvm-project main llvmorg-17-init-19304-gd0b54bb50e51

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-17-init-19304-gd0b54bb50e51, the
last commit before the upstream release/17.x branch was created.

PR: 273753
MFC after: 1 month

(cherry picked from commit 06c3fb2749bda94cb5201f81ffdb8fa6c3161b2e)

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Revert r357259, after the merge from head which added linker scripts for
stand/i386 boot:

Revert upstream lld r371957 (git commit 06bb7dfbd) by Fangrui Song:

[ELF] Map the ELF header at imageBase

Revert r357259, after the merge from head which added linker scripts for
stand/i386 boot:

Revert upstream lld r371957 (git commit 06bb7dfbd) by Fangrui Song:

[ELF] Map the ELF header at imageBase

If there is no readonly section, we map:

* The ELF header at imageBase+maxPageSize
* Program headers at imageBase+maxPageSize+sizeof(Ehdr)
* The first section .text at imageBase+maxPageSize+sizeof(Ehdr)+sizeof(program headers)

Due to the interaction between Writer<ELFT>::fixSectionAlignments and
LinkerScript::allocateHeaders,
`alignDown(p_vaddr(R PT_LOAD)) = alignDown(p_vaddr(RX PT_LOAD))`.
The RX PT_LOAD will override the R PT_LOAD at runtime, which is not ideal:

```
// PHDR at 0x401034, should be 0x400034
PHDR 0x000034 0x00401034 0x00401034 0x000a0 0x000a0 R 0x4
// R PT_LOAD contains just Ehdr and program headers.
// At 0x401000, should be 0x400000
LOAD 0x000000 0x00401000 0x00401000 0x000d4 0x000d4 R 0x1000
LOAD 0x0000d4 0x004010d4 0x004010d4 0x00001 0x00001 R E 0x1000
```

* createPhdrs allocates the headers to the R PT_LOAD.
* fixSectionAlignments assigns `imageBase+maxPageSize+sizeof(Ehdr)+sizeof(program headers)` (formula: `alignTo(dot, maxPageSize) + dot % config->maxPageSize`) to addrExpr of .text
* allocateHeaders computes the minimum address among SHF_ALLOC sections, i.e. addr(.text)
* allocateHeaders sets address of ELF header to `addr(.text)-sizeof(Ehdr)-sizeof(program headers) = imageBase+maxPageSize`

The main observation is that when the SECTIONS command is not used, we
don't have to call allocateHeaders. This requires an assumption that
the presence of PT_PHDR and addresses of headers can be decided
regardless of address information.

This may seem natural because dot is not manipulated by a linker script.
The other thing is that we have to drop the special rule for -T<section>
in `getInitialDot`. If -Ttext is smaller than the image base, the headers
will not be allocated with the old behavior (allocateHeaders is called)
but always allocated with the new behavior.

The behavior change is not a problem. Whether and where headers are
allocated can vary among linkers, or ld.bfd across different versions
(--enable-separate-code or not). It is thus advised to use a linker
script with the PHDRS command to have a consistent behavior across
linkers. If PT_PHDR is needed, an explicit --image-base can be a simpler
alternative.

Differential Revision: https://reviews.llvm.org/D67325

llvm-svn: 371957

show more ...

Revert upstream lld r371957 (git commit 06bb7dfbd) by Fangrui Song:

[ELF] Map the ELF header at imageBase

If there is no readonly section, we map:

* The ELF header at imageBase+maxPageSize

Revert upstream lld r371957 (git commit 06bb7dfbd) by Fangrui Song:

[ELF] Map the ELF header at imageBase

If there is no readonly section, we map:

* The ELF header at imageBase+maxPageSize
* Program headers at imageBase+maxPageSize+sizeof(Ehdr)
* The first section .text at imageBase+maxPageSize+sizeof(Ehdr)+sizeof(program headers)

Due to the interaction between Writer<ELFT>::fixSectionAlignments and
LinkerScript::allocateHeaders,
`alignDown(p_vaddr(R PT_LOAD)) = alignDown(p_vaddr(RX PT_LOAD))`.
The RX PT_LOAD will override the R PT_LOAD at runtime, which is not ideal:

```
// PHDR at 0x401034, should be 0x400034
PHDR 0x000034 0x00401034 0x00401034 0x000a0 0x000a0 R 0x4
// R PT_LOAD contains just Ehdr and program headers.
// At 0x401000, should be 0x400000
LOAD 0x000000 0x00401000 0x00401000 0x000d4 0x000d4 R 0x1000
LOAD 0x0000d4 0x004010d4 0x004010d4 0x00001 0x00001 R E 0x1000
```

* createPhdrs allocates the headers to the R PT_LOAD.
* fixSectionAlignments assigns `imageBase+maxPageSize+sizeof(Ehdr)+sizeof(program headers)` (formula: `alignTo(dot, maxPageSize) + dot % config->maxPageSize`) to addrExpr of .text
* allocateHeaders computes the minimum address among SHF_ALLOC sections, i.e. addr(.text)
* allocateHeaders sets address of ELF header to `addr(.text)-sizeof(Ehdr)-sizeof(program headers) = imageBase+maxPageSize`

The main observation is that when the SECTIONS command is not used, we
don't have to call allocateHeaders. This requires an assumption that
the presence of PT_PHDR and addresses of headers can be decided
regardless of address information.

This may seem natural because dot is not manipulated by a linker script.
The other thing is that we have to drop the special rule for -T<section>
in `getInitialDot`. If -Ttext is smaller than the image base, the headers
will not be allocated with the old behavior (allocateHeaders is called)
but always allocated with the new behavior.

The behavior change is not a problem. Whether and where headers are
allocated can vary among linkers, or ld.bfd across different versions
(--enable-separate-code or not). It is thus advised to use a linker
script with the PHDRS command to have a consistent behavior across
linkers. If PT_PHDR is needed, an explicit --image-base can be a simpler
alternative.

Differential Revision: https://reviews.llvm.org/D67325

llvm-svn: 371957

This causes "ld: error: output file too large: 18446744073707016908
bytes" when linking our loader_4th and loader_lua. Clearly, something
is wrong when using -Ttext 0x0: I will file an upstream bug report for
this.

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Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That i

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

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