From ff5a8ad2abb45955dbeda46273242d6f0186cf2c Mon Sep 17 00:00:00 2001 From: Oli Scherer Date: Mon, 24 Feb 2025 09:22:41 +0000 Subject: [PATCH] Explain the actual reason why stripping binders is fine --- .../rustc_monomorphize/src/partitioning/autodiff.rs | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/compiler/rustc_monomorphize/src/partitioning/autodiff.rs b/compiler/rustc_monomorphize/src/partitioning/autodiff.rs index 0c855508434..378b98c2807 100644 --- a/compiler/rustc_monomorphize/src/partitioning/autodiff.rs +++ b/compiler/rustc_monomorphize/src/partitioning/autodiff.rs @@ -12,15 +12,14 @@ fn adjust_activity_to_abi<'tcx>(tcx: TyCtxt<'tcx>, fn_ty: Ty<'tcx>, da: &mut Vec if !matches!(fn_ty.kind(), ty::FnDef(..)) { bug!("expected fn def for autodiff, got {:?}", fn_ty); } - let fnc_binder: ty::Binder<'_, ty::FnSig<'_>> = fn_ty.fn_sig(tcx); - // If rustc compiles the unmodified primal, we know that this copy of the function - // also has correct lifetimes. We know that Enzyme won't free the shadow too early - // (or actually at all), so let's strip lifetimes when computing the layout. - let x = tcx.instantiate_bound_regions_with_erased(fnc_binder); + // We don't actually pass the types back into the type system. + // All we do is decide how to handle the arguments. + let sig = fn_ty.fn_sig(tcx).skip_binder(); + let mut new_activities = vec![]; let mut new_positions = vec![]; - for (i, ty) in x.inputs().iter().enumerate() { + for (i, ty) in sig.inputs().iter().enumerate() { if let Some(inner_ty) = ty.builtin_deref(true) { if ty.is_fn_ptr() { // FIXME(ZuseZ4): add a nicer error, or just figure out how to support them,