diff --git a/base/compiler/optimize.jl b/base/compiler/optimize.jl
index e2ef24a64c620..d83a7da62dafc 100644
--- a/base/compiler/optimize.jl
+++ b/base/compiler/optimize.jl
@@ -564,16 +564,16 @@ function ipo_dataflow_analysis!(interp::AbstractInterpreter, ir::IRCode, result:
         bstmt = ir[barg][:stmt]
         isexpr(bstmt, :boundscheck) || return false
         # If IR_FLAG_INBOUNDS is already set, no more conditional ub
-        (length(bstmt.args) != 0 && bstmt.args[1] === false) && return false
+        (!isempty(bstmt.args) && bstmt.args[1] === false) && return false
         any_conditional_ub = true
         return true
     end
 
     function scan_non_dataflow_flags!(inst::Instruction)
         flag = inst[:flag]
-        all_effect_free &= (flag & IR_FLAG_EFFECT_FREE) != 0
-        all_nothrow &= (flag & IR_FLAG_NOTHROW) != 0
-        if (flag & IR_FLAG_NOUB) == 0
+        all_effect_free &= !iszero(flag & IR_FLAG_EFFECT_FREE)
+        all_nothrow &= !iszero(flag & IR_FLAG_NOTHROW)
+        if iszero(flag & IR_FLAG_NOUB)
             if !is_conditional_noub(inst)
                 all_noub = false
             end
@@ -582,7 +582,7 @@ function ipo_dataflow_analysis!(interp::AbstractInterpreter, ir::IRCode, result:
 
     function scan_inconsistency!(inst::Instruction, idx::Int)
         flag = inst[:flag]
-        stmt_inconsistent = (flag & IR_FLAG_CONSISTENT) == 0
+        stmt_inconsistent = iszero(flag & IR_FLAG_CONSISTENT)
         stmt = inst[:stmt]
         # Special case: For getfield, we allow inconsistency of the :boundscheck argument
         if is_getfield_with_boundscheck_arg(inst)
@@ -606,7 +606,7 @@ function ipo_dataflow_analysis!(interp::AbstractInterpreter, ir::IRCode, result:
         return stmt_inconsistent
     end
 
-    function scan_stmt!(inst, idx, lstmt, bb)
+    function scan_stmt!(inst::Instruction, idx::Int, lstmt::Int, bb::Int)
         stmt = inst[:inst]
         flag = inst[:flag]
 
diff --git a/base/compiler/ssair/irinterp.jl b/base/compiler/ssair/irinterp.jl
index 608fe4d915c6c..da3ff45bea4ab 100644
--- a/base/compiler/ssair/irinterp.jl
+++ b/base/compiler/ssair/irinterp.jl
@@ -217,7 +217,7 @@ function BBScanner(ir::IRCode)
     return BBScanner(ir, bb_ip)
 end
 
-function scan!(callback, scanner::BBScanner, forwards_only::Bool)
+function scan!(@specialize(callback), scanner::BBScanner, forwards_only::Bool)
     (; bb_ip, ir) = scanner
     bbs = ir.cfg.blocks
     while !isempty(bb_ip)
@@ -235,7 +235,7 @@ function scan!(callback, scanner::BBScanner, forwards_only::Bool)
 end
 
 function populate_def_use_map!(tpdum::TwoPhaseDefUseMap, scanner::BBScanner)
-    scan!(scanner, false) do inst, idx, lstmt, bb
+    scan!(scanner, false) do inst::Instruction, idx::Int, lstmt::Int, bb::Int
         for ur in userefs(inst)
             val = ur[]
             if isa(val, SSAValue)
@@ -262,7 +262,7 @@ function _ir_abstract_constant_propagation(interp::AbstractInterpreter, irsv::IR
     # Fast path: Scan both use counts and refinement in one single pass of
     #            of the instructions. In the absence of backedges, this will
     #            converge.
-    completed_scan = scan!(scanner, true) do inst, idx, lstmt, bb
+    completed_scan = scan!(scanner, true) do inst::Instruction, idx::Int, lstmt::Int, bb::Int
         irsv.curridx = idx
         stmt = ir.stmts[idx][:inst]
         typ = ir.stmts[idx][:type]
@@ -315,7 +315,7 @@ function _ir_abstract_constant_propagation(interp::AbstractInterpreter, irsv::IR
         stmt_ip = BitSetBoundedMinPrioritySet(length(ir.stmts))
 
         # Slow Path Phase 1.A: Complete use scanning
-        scan!(scanner, false) do inst, idx, lstmt, bb
+        scan!(scanner, false) do inst::Instruction, idx::Int, lstmt::Int, bb::Int
             irsv.curridx = idx
             stmt = inst[:inst]
             flag = inst[:flag]
diff --git a/base/compiler/typeinfer.jl b/base/compiler/typeinfer.jl
index f4ea69b310415..e4f143e0c75b6 100644
--- a/base/compiler/typeinfer.jl
+++ b/base/compiler/typeinfer.jl
@@ -464,7 +464,6 @@ function adjust_effects(ipo_effects::Effects, def::Method)
     return ipo_effects
 end
 
-
 function adjust_effects(sv::InferenceState)
     ipo_effects = sv.ipo_effects
 
@@ -554,7 +553,6 @@ function finish(me::InferenceState, interp::AbstractInterpreter)
     me.result.result = bestguess
     me.ipo_effects = me.result.ipo_effects = adjust_effects(me)
 
-
     if limited_ret
         # a parent may be cached still, but not this intermediate work:
         # we can throw everything else away now