effects: improve tri-state printing

Author: aviatesk

base/compiler/ssair/show.jl

@@ -791,7 +791,11 @@ function show_ir(io::IO, code::Union{IRCode, CodeInfo}, config::IRShowConfig=def
 end
 
 tristate_letter(t::TriState) = t === ALWAYS_TRUE ? '+' : t === ALWAYS_FALSE ? '!' : '?'
-tristate_color(t::TriState) = t === ALWAYS_TRUE ? :green : t === ALWAYS_FALSE ? :red : :orange
+tristate_color(t::TriState) = t === ALWAYS_TRUE ? :green : t === ALWAYS_FALSE ? :red : :yellow
+tristate_repr(t::TriState) =
+    t === ALWAYS_TRUE ? "ALWAYS_TRUE" :
+    t === ALWAYS_FALSE ? "ALWAYS_FALSE" :
+    t === TRISTATE_UNKNOWN ? "TRISTATE_UNKNOWN" : nothing
 
 function Base.show(io::IO, e::Core.Compiler.Effects)
     print(io, "(")
@@ -808,4 +812,13 @@ function Base.show(io::IO, e::Core.Compiler.Effects)
     e.nonoverlayed || printstyled(io, '′'; color=:red)
 end
 
+function Base.show(io::IO, t::TriState)
+    s = tristate_repr(t)
+    if s !== nothing
+        printstyled(io, s; color = tristate_color(t))
+    else # unknown state, redirect to the fallback printing
+        Base.@invoke show(io::IO, t::Any)
+    end
+end
+
 @specialize

base/show.jl

@@ -2558,7 +2558,7 @@ module IRShow
     import ..Base
     import .Compiler: IRCode, ReturnNode, GotoIfNot, CFG, scan_ssa_use!, Argument,
         isexpr, compute_basic_blocks, block_for_inst,
-        TriState, Effects, ALWAYS_TRUE, ALWAYS_FALSE
+        TriState, Effects, ALWAYS_TRUE, ALWAYS_FALSE, TRISTATE_UNKNOWN
     Base.getindex(r::Compiler.StmtRange, ind::Integer) = Compiler.getindex(r, ind)
     Base.size(r::Compiler.StmtRange) = Compiler.size(r)
     Base.first(r::Compiler.StmtRange) = Compiler.first(r)