diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs index dd2b9d59366ea..c3aabb16a9b9a 100644 --- a/src/bootstrap/compile.rs +++ b/src/bootstrap/compile.rs @@ -658,7 +658,12 @@ impl Step for Rustc { // 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"); }