Really exciting news! This should mitigate a longstanding problem that Rust developers have had when iterating.

Trying cranelift for the first time (I think).

Let’s create a “release-dev-cl” profile that inherits “release-dev” profile and compare.

For reference, “release-dev” is:

inherits = "release"
debug = "full"
codegen-units = 8
lto = "off"

Cool, cold builds (including deps) went from 73s to 37s, with zstd-sys becoming a bigger offender.

But but but…

warning: unsupported x86 llvm intrinsic llvm.x86.aesni.aesimc; replacing with trap
warning: unsupported x86 llvm intrinsic llvm.x86.aesni.aesdec; replacing with trap
warning: unsupported x86 llvm intrinsic llvm.x86.aesni.aesdeclast; replacing with trap

Alright. Which dep is using this. Let’s cargo vendor and rg.

% cargo vendor &>/dev/null
% cd vendor
% rg -l 'aesimc|aesdec|aesdeclast' | sed 's|/.*||' | sort -u
aes
ring

reported

Alright, let’s try another project…

Nice, this one goes from 52s to 19s, and no unsupported intrinsics.

Let’s test the binary.

Hmm, it’s orders of magnitude slower… let’s perf…

• LLVM

   1.71%  async-global-ex  abcd-cli              [.] alloc::collections::btree::map::IntoIterᐸK,V,Aᐳ::dying_next                                   
   1.66%  async-global-ex  abcd-cli              [.] ᐸalloc::collections::btree::map::KeysᐸK,Vᐳ as core::iter::traits::iterator::Iteratorᐳ::next   
   1.53%  async-global-ex  libc.so.6             [.] 0x0000000000158c4a                                                                            
   1.48%  blocking-4       abcd-cli              [.] ᐸlz4_flex::frame::decompress::FrameDecoderᐸRᐳ as std::io::Readᐳ::read_to_end                  
   1.35%  async-global-ex  libc.so.6             [.] 0x000000000015818d                                                                            
   1.28%  blocking-1       abcd-cli              [.] ᐸlz4_flex::frame::decompress::FrameDecoderᐸRᐳ as std::io::Readᐳ::read_to_end                  
   1.25%  blocking-4       abcd-cli              [.] ᐸcore::iter::adapters::map::MapᐸI,Fᐳ as core::iter::traits::iterator::Iteratorᐳ::try_fold     
   1.25%  async-global-ex  libc.so.6             [.] malloc                                                                                        
   1.19%  blocking-4       libc.so.6             [.] malloc                                                                                        
   1.12%  blocking-2       abcd-cli              [.] ᐸlz4_flex::frame::decompress::FrameDecoderᐸRᐳ as std::io::Readᐳ::read_to_end                  
   1.06%  async-global-ex  libc.so.6             [.] 0x0000000000158487                                                                            
   0.99%  async-global-ex  abcd-cli              [.] ᐸalloc::collections::btree::map::BTreeMapᐸK,V,Aᐳ as core::ops::drop::Dropᐳ::drop              
   0.92%  blocking-2       libc.so.6             [.] malloc                                                                                        
   0.91%  blocking-4       libc.so.6             [.] 0x0000000000158180                                                                            
   0.85%  blocking-2       [kernel.vmlinux]      [k] clear_page_erms                                                                               
   0.84%  async-global-ex  abcd-cli              [.] alloc::collections::btree::search::ᐸimpl alloc::collections::btree::node::NodeRefᐸBorrowType, 
   0.81%  async-global-ex  abcd-cli              [.] abcd::all::ELSMap::mk_extr