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[RFC] Roadmap to minimize libtaichi_c_api.so library size #6793

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jim19930609 opened this issue Dec 2, 2022 · 2 comments
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[RFC] Roadmap to minimize libtaichi_c_api.so library size #6793

jim19930609 opened this issue Dec 2, 2022 · 2 comments
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jim19930609 commented Dec 2, 2022 •
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We roughly planed three stages to optimize the library size for libtaichi_c_api.so:

  • Function level linking
  • Symbol rearrangement and clean up
  • Customized C-API features pruning

1. Turn on function-level linking

1.1 Convert CMake OBJECT targets to STATIC targets

Removes unnecessary entry files that compiles into libtaichi_c_api.so

[Before]
image

[After]
image

1.2 Apply version script to libtaichi_c_api.so

Convert unnecessary global symbols to local symbols, leading to more optimization opportunities.
[Before]
image

[After]
image

1.3 Add compile option -ffunction-sections, -fdata-sections and link option --gc-sections

Turns on function level linking eventually.
[Before]
image

[After]
image

Based on some experiment results, after turning on function-level-linking, we're expecting ~80% code size reduction from 12 MB to 1.7 MB (Vulkan C-API library, #6388)

2. Symbol rearrangement and clean up

Further detect and clean up redundant symbols via symbol analysis (tooling: https://github.com/google/bloaty)

Symbol class Symbol keyword Size / KB Side notes / KB
libtaichi_c_api.so [Total Size] 1700  
 
RTTI + vtable "vtable for" 27  
RTTI + vtable "typeinfo name for" 9  
RTTI + vtable "typeinfo for" 16  
  [Sum] 52  
 
Vulkan "vkapi::" 39 [std::_Sp_counted_ptr]: 5[DeviceObjVk]: 23[vkapi::create_xxxx]: 11
Vulkan "taichi::lang::vulkan" 173 [VulkanStream]: 11[VulkanDevice]: 69[VulkanSurface]: 10[VulkanCommandList]: 32[VulkanResourceBinder]: 16[VulkanPipeline]: 18[VulkanRenderPass]: 3[Helper Functions]: 12
Vulkan "vma" 3 [external] VulkanMemoryAllocatorvmaAllocateMemoryForBuffervmaAllocateMemoryForImage
Vulkan "Vma" 60 [VmaBlockVector]: 8[VmaBlockMetadata]: 26[VmaAllocator_T]: 18[VmaVector + VmaPoolAllocator + VmaJsonWriter]: 8
Vulkan "volk" 29 [external] volkvolkGenLoadInstance
Vulkan "taichi::lang::gfx" 43  
  [Sum] 350  
 
SpirV "taichi::lang::spirv" 24 [Internal]
SpirV "spv" 11 [external] SPIRV-Tools
SpirV "spdlog::" 84 [external] spdlogspdlog::details::R_formatter
  [Sum] 119  
 
Taichi "taichi::" 90 [taichi::BinarySerializer]: 18[taichi::zip]: 6[taichi::lang::aot]: 19[Ndarray]: 3[Type]: 15[Device]: 9[Logger]: 4[Rest]: 12
 
Redundant "fmt::v6" 112 [external]
Redundant "tinfl" 8 [external] miniz (compression)
Redundant "glfw" 114 [external] glfw
Redundant "mz_" 8 [external] miniz (compression)
  [Sum] 242  
 
Standard Library "std::" 20 Standard library
Standard Library "_GLOBAL__sub_I" 47 Iostream related
  [Sum] 67  
 
       
Sections .rodata 178 const strings
Sections .gcc_exept_table 456 Exception handles
Sections .rela.dyn 13.7
Sections .dynstr 4.57
Sections .dynsym 4.64
Sections ... ...  
  [Sum] 673  
       
CAPI [Sum] 25  
Rest [Sum] 63 Third-party libraries[spirv_reflect] ParseDescriptorBlockVariable

3. Customized C-API features

In certain situations, library size can be the killing blocker to ship a product. Therefore we should provide options to further remove unimportant features to further reduce the library size. Some possible options are:

  1. Remove C++ exceptions handling and turn on fno-except
  2. Remove RTTI information and turn on fno-rtti
  3. Prune useless C-API interfaces to the user.
@jim19930609 jim19930609 added the doc Documentation related issues & PRs label Dec 2, 2022
@taichi-gardener taichi-gardener moved this to Untriaged in Taichi Lang Dec 2, 2022
@jim19930609 jim19930609 moved this from Untriaged to Todo in Taichi Lang Dec 2, 2022
@jim19930609 jim19930609 self-assigned this Dec 2, 2022
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ailzhang commented Dec 5, 2022

cc: @ghuau-innopeak

This was referenced Dec 6, 2022
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jim19930609 added a commit that referenced this issue Dec 8, 2022
@jim19930609
[build] Refactored and removed RuntimeCUDA and RuntimeCUDAInjector (#…
c179aca 
…6830)

Issue: #6793

### Brief Summary
This was referenced Dec 8, 2022
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jim19930609 added a commit that referenced this issue Dec 9, 2022
@jim19930609
[build] Migrate cmake targets from OBJECT to STATIC for libtaichi_c_a…
a87b98f 
…pi.so (#6831)

Issue: #6793

### Brief Summary
@jim19930609 jim19930609 mentioned this issue Dec 9, 2022
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jim19930609 commented Dec 9, 2022 •
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After turning on function level linking for libtaichi_c_api.so with #6840 as well as stripping the debug info with #6845, significant code size reduction was observed:

  Size (Original) Size (Optimized)
[Linux] Vulkan 14 MB 1.5 MB
[Android] Vulkan 14 MB 1.6 MB
[Linux] Vulkan + LLVM 82 MB 51 MB

libtaichi_c_api.so built with LLVM does not benefit that much from function level linking, mainly because libLLVM.a is not compiled with -ffunction-sections -fdata-sections. We'll have that fixed later.

TODO List:

  1. Recompile third-party libraries with -ffunction-sections -fdata-sections, especially LLVM
  2. Turn on function level linking for taichi_python.so as well, which has two prerequisite tasks:

jim19930609 added a commit that referenced this issue Dec 13, 2022
@jim19930609
[build] Turn on function level linking for taichi_c_api (#6840)
fd6cbe9 
Issue: #6793

### Brief Summary
jim19930609 added a commit that referenced this issue Dec 13, 2022
@jim19930609
[build] Enable strip for libtaichi_c_api.so with Release Build (#6845)
9f78a2f 
Issue: #6793

  | Size (Original) | Size (Optimized)
-- | -- | --
Vulkan | 14 MB | 1.5 MB
Vulkan + LLVM | 82 MB | 51 MB

libtaichi_c_api.so built with LLVM does not benefit much from function
level linking, mainly because libLLVM.a is not compiled with
`-ffunction-sections -fdata-sections`. We'll have that fixed later.
quadpixels pushed a commit to quadpixels/taichi that referenced this issue May 13, 2023
@jim19930609 @quadpixels
[build] Refactored and removed RuntimeCUDA and RuntimeCUDAInjector (t…
b5cce05 
…aichi-dev#6830)

Issue: taichi-dev#6793

### Brief Summary
quadpixels pushed a commit to quadpixels/taichi that referenced this issue May 13, 2023
@jim19930609 @quadpixels
[build] Migrate cmake targets from OBJECT to STATIC for libtaichi_c_a…
7c83aed 
…pi.so (taichi-dev#6831)

Issue: taichi-dev#6793

### Brief Summary
quadpixels pushed a commit to quadpixels/taichi that referenced this issue May 13, 2023
@jim19930609 @quadpixels
[build] Turn on function level linking for taichi_c_api (taichi-dev#6840
a1c73cb 
)

Issue: taichi-dev#6793

### Brief Summary
quadpixels pushed a commit to quadpixels/taichi that referenced this issue May 13, 2023
@jim19930609 @quadpixels
[build] Enable strip for libtaichi_c_api.so with Release Build (taich…
a49e570 
…i-dev#6845)

Issue: taichi-dev#6793

  | Size (Original) | Size (Optimized)
-- | -- | --
Vulkan | 14 MB | 1.5 MB
Vulkan + LLVM | 82 MB | 51 MB

libtaichi_c_api.so built with LLVM does not benefit much from function
level linking, mainly because libLLVM.a is not compiled with
`-ffunction-sections -fdata-sections`. We'll have that fixed later.
@github-project-automation github-project-automation bot moved this from Todo to Done in Taichi Lang Jun 23, 2023
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