ZJIT: Remove GuardType deduplication (#16927)

Now that ece14b61f505eea1ebefb3b8295df0fcf4d22567 has landed, we get
this for free.

We will eventually add value numbering, which will do more, but for now
remove this ad-hoc code.

1 files changed, 0 insertions, 19 deletions

diff --git a/zjit/src/hir.rs b/zjit/src/hir.rs
index f3f6f73e3f..2e72737ca1 100644
--- a/zjit/src/hir.rs
+++ b/zjit/src/hir.rs
@@ -5018,10 +5018,6 @@ impl Function {
         for block in self.rpo() {
             let old_insns = std::mem::take(&mut self.blocks[block.0].insns);
             let mut new_insns = vec![];
-            // Track guards seen so far in this block: (val, guard_type, result_insn_id).
-            // When we encounter a GuardType whose (val, guard_type) pair is already covered
-            // by a previous guard, we can eliminate it by reusing the earlier result.
-            let mut seen_guards: Vec<(InsnId, Type, InsnId)> = vec![];
             for insn_id in old_insns {
                 let replacement_id = match self.find(insn_id) {
                     Insn::GuardType { val, guard_type, .. } if self.is_a(val, guard_type) => {
@@ -5029,21 +5025,6 @@ impl Function {
                         // Don't bother re-inferring the type of val; we already know it.
                         continue;
                     }
-                    // Deduplicate GuardType: if we already guarded the same val with a
-                    // type that is the same or narrower, the new guard is redundant.
-                    // e.g. if we already proved val is Fixnum, a later Fixnum or
-                    // BasicObject guard on the same val is guaranteed to pass.
-                    // TODO: Move into global value numbering
-                    Insn::GuardType { val, guard_type, .. } => {
-                        if let Some(&(_, _, prev_result)) = seen_guards.iter().find(
-                            |&&(prev_val, prev_type, _)| prev_val == val && prev_type.is_subtype(guard_type)
-                        ) {
-                            self.make_equal_to(insn_id, prev_result);
-                            continue;
-                        }
-                        seen_guards.push((val, guard_type, insn_id));
-                        insn_id
-                    }
                     Insn::LoadField { recv, offset, return_type, .. } if return_type.is_subtype(types::BasicObject) &&
                             u32::try_from(offset).is_ok() => {
                         let offset = (offset as u32).to_usize();