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Fangrui Song b498d99338 [ELF] Start a new PT_LOAD if LMA region is different 
GNU ld has a counterintuitive lang_propagate_lma_regions rule.

```
// .foo's LMA region is propagated to .bar because their VMA region is the same,
// and .bar does not have an explicit output section address (addr_tree).
.foo : { *(.foo) } >RAM AT> FLASH
.bar : { *(.bar) } >RAM

// An explicit output section address disables propagation.
.foo : { *(.foo) } >RAM AT> FLASH
.bar . : { *(.bar) } >RAM
```

In both cases, lld thinks .foo's LMA region is propagated and
places .bar in the same PT_LOAD, so lld diverges from GNU ld w.r.t. the
second case (lma-align.test).

This patch changes Writer<ELFT>::createPhdrs to disable propagation
(start a new PT_LOAD). A user of the first case can make linker scripts
portable by explicitly specifying `AT>`. By contrast, there was no
workaround for the old behavior.

This change uncovers another LMA related bug in assignOffsets() where
`ctx->lmaOffset = 0;` was omitted. It caused a spurious "load address
range overlaps" error for at2.test

The new PT_LOAD rule is complex. For convenience, I listed the origins of some subexpressions:

* rL323449: `sec->memRegion == load->firstSec->memRegion`; linkerscript/at3.test
* D43284: `load->lastSec == Out::programHeaders` (don't start a new PT_LOAD after program headers); linkerscript/at4.test
* D58892: `sec != relroEnd` (start a new PT_LOAD after PT_GNU_RELRO)

Reviewed By: psmith

Differential Revision: https://reviews.llvm.org/D74297
 		2020-02-12 08:20:14 -08:00
..
COFF [lld] Replace SmallStr.str().str() with std::string conversion operator. 2020-01-29 21:30:21 -08:00
Common Make llvm::StringRef to std::string conversions explicit. 2020-01-28 23:25:25 +01:00
ELF [ELF] Start a new PT_LOAD if LMA region is different 2020-02-12 08:20:14 -08:00
MinGW [lld] Replace SmallStr.str().str() with std::string conversion operator. 2020-01-29 21:30:21 -08:00
cmake/modules
…
docs Bump the trunk major version to 11 2020-01-15 13:38:01 +01:00
include/lld Make llvm::StringRef to std::string conversions explicit. 2020-01-28 23:25:25 +01:00
lib Make llvm::StringRef to std::string conversions explicit. 2020-01-28 23:25:25 +01:00
test [ELF] Start a new PT_LOAD if LMA region is different 2020-02-12 08:20:14 -08:00
tools/lld Make it possible to redirect not only errs() but also outs() 2019-11-18 11:18:06 +09:00
unittests Make llvm::StringRef to std::string conversions explicit. 2020-01-28 23:25:25 +01:00
utils Python 2/3 compatibility 2019-03-20 07:42:13 +00:00
wasm [lld][WebAssembly] Fail if bitcode objects are pulled in after LTO 2020-02-11 17:36:15 -08:00
.arcconfig
…
.clang-format
…
.gitignore
…
CMakeLists.txt try to unbreak build after 4b6d9ac392 2020-01-16 10:12:35 -05:00
CODE_OWNERS.TXT
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LICENSE.TXT Fix typos throughout the license files that somehow I and my reviewers 2019-01-21 09:52:34 +00:00
README.md
…

README.md

LLVM Linker (lld)

This directory and its subdirectories contain source code for the LLVM Linker, a modular cross platform linker which is built as part of the LLVM compiler infrastructure project.

lld is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt.

Benchmarking

In order to make sure various developers can evaluate patches over the same tests, we create a collection of self contained programs.

It is hosted at https://s3-us-west-2.amazonaws.com/linker-tests/lld-speed-test.tar.xz

The current sha256 is 10eec685463d5a8bbf08d77f4ca96282161d396c65bd97dc99dbde644a31610f.