[PATCH] D74764: [yaml2obj][WIP] - Automatically assign VA for allocatable sections.

[Fangrui Song via Phabricator via llvm-commits]

MaskRay added a comment.

I think this is the correct approach. It will definitely simplify tests.

Nit: in the description, use `sh_addr` instead of `VA` because `sh_addr` may be more familiar to readers.



================
Comment at: llvm/lib/ObjectYAML/ELFEmitter.cpp:222
 
+  void assignSectionAddress(Elf_Shdr &SHeader, ELFYAML::Section* YAMLSec);
+
----------------
`Section *`


================
Comment at: llvm/lib/ObjectYAML/ELFEmitter.cpp:397
 
+  LocationCounter += Header.sh_size;
+
----------------
Add a test that `ShSize` (overriding sh_size, usually used for abnormal values) does not affect `LocationCounter`.


================
Comment at: llvm/lib/ObjectYAML/ELFEmitter.cpp:527
+
+  if (!(SHeader.sh_flags & ELF::SHF_ALLOC))
+    return;
----------------
Delete. I think non-SHF_ALLOC sections follow the same rule.


================
Comment at: llvm/lib/ObjectYAML/ELFEmitter.cpp:531
+  LocationCounter =
+      alignTo(LocationCounter, SHeader.sh_addralign ? SHeader.sh_addralign : 1);
+  SHeader.sh_addr = LocationCounter;
----------------
getValueOr


================
Comment at: llvm/test/tools/yaml2obj/ELF/section-address-assign.yaml:31
+    Flags:   [ SHF_ALLOC ]
+    Address: 0x1000
+    Size:    0x3
----------------
0x1000 is fine but probably not the best.

If .text.any.addr is included by a PT_LOAD, one will expect `sh_offset%p_align = sh_addr%p_align` (a PT_LOAD's p_align is usually 0x1000 (maxpagesize) on x86).

One approach is to specify sh_addralign and set sh_addr to sh_addralign plus a multiple of p_align.

```
    Address: 0x1200
    AddressAlign: 0x200
```


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  https://reviews.llvm.org/D74764/new/

https://reviews.llvm.org/D74764