// With LLD, we can use ICF (identical code folding) to reduce the executable size
// of librustc_driver/rustc and to improve i-cache utilization.
- if builder.config.use_lld {
+ //
+ // -Wl,[link options] doesn't work on MSVC. However, /OPT:ICF (technically /OPT:REF,ICF)
+ // is already on by default in MSVC optimized builds, which is interpreted as --icf=all:
+ // https://github.com/llvm/llvm-project/blob/3329cec2f79185bafd678f310fafadba2a8c76d2/lld/COFF/Driver.cpp#L1746
+ // https://github.com/rust-lang/rust/blob/f22819bcce4abaff7d1246a56eec493418f9f4ee/compiler/rustc_codegen_ssa/src/back/linker.rs#L827
+ if builder.config.use_lld && !compiler.host.contains("msvc") {
cargo.rustflag("-Clink-args=-Wl,--icf=all");
}