From c50c745fa88f0850c8e8ebed37749118929d7e87 Mon Sep 17 00:00:00 2001 From: Vlad Brezae Date: Fri, 27 Jan 2023 16:26:56 +0200 Subject: [PATCH] [mono][interp] Reduce redundant moves with calls (#79905) We were marking INTERP_LOCAL_FLAG_NO_CALL_ARGS for source vars of non calls. With further optimizations, the var could end up being used only for the call but we never unset the flag. Reuse the ref count data, which is kept updated following optimizations, to achieve same thing. If cprop is not run then we always duplicate the args, but this is an unused scenario. --- src/mono/mono/mini/interp/transform.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/src/mono/mono/mini/interp/transform.c b/src/mono/mono/mini/interp/transform.c index 0fda118..9f99a17 100644 --- a/src/mono/mono/mini/interp/transform.c +++ b/src/mono/mono/mini/interp/transform.c @@ -9194,11 +9194,6 @@ retry: } } else { cprop_sreg (td, ins, &sregs [i], local_defs); - // This var is used as a source to a normal instruction. In case this var will - // also be used as source to a call, make sure the offset allocator will create - // a new temporary call arg var and not use this one. Call arg vars have special - // semantics. They can be assigned only once and they die once the call is made. - td->locals [sregs [i]].flags |= INTERP_LOCAL_FLAG_NO_CALL_ARGS; } } @@ -10389,9 +10384,12 @@ interp_alloc_offsets (TransformData *td) while (var != -1) { if (td->locals [var].flags & INTERP_LOCAL_FLAG_GLOBAL || + !td->local_ref_count || td->local_ref_count [var] > 1 || td->locals [var].flags & INTERP_LOCAL_FLAG_NO_CALL_ARGS) { - // A global var is an argument to a call, which is not allowed. We need - // to copy the global var into a local var + // Some vars can't be allocated on the call args stack, since the constraint is that + // call args vars die after the call. This isn't necessarily true for global vars or + // vars that are used by other instructions aside from the call. + // We need to copy the var into a new tmp var int new_var = create_interp_local (td, td->locals [var].type); td->locals [new_var].call = ins; td->locals [new_var].flags |= INTERP_LOCAL_FLAG_CALL_ARGS; -- 2.7.4