refine IR model queries (#58661)

- `jl_isa_ast_node` was missing `enter`/`leave` nodes.
 - `Core.IR` exports mistakenly included a function `memoryref`.
 - `Base.IR`, and `quoted` were not public or documented.
 - Add julia function `isa_ast_node` to improve accuracy of `quoted`.
- Change `==` on AST nodes to check egal equality of any constants in
the IR / AST, and make hashing consistent with that change. This
helpfully allows determining that `x + 1` and `x + 1.0` are not
equivalent, exchangeable operations. If you need to compare any two
objects for semantic equality, you may need to first wrap them with `x =
Base.isa_ast_node(x) ? x : QuoteNode(x)` to resolve the ambiguity of
whether the comparison is of the semantics or value.
 - Handle `undef` fields in Phi/PhiC node equality and hashing

Author: vtjnash

Compiler/src/ssair/slot2ssa.jl

@@ -8,7 +8,7 @@ end
 SlotInfo() = SlotInfo(Int[], Int[], false)
 
 function scan_entry!(result::Vector{SlotInfo}, idx::Int, @nospecialize(stmt))
-    # NewVarNodes count as defs for the purpose
+    # NewvarNodes count as defs for the purpose
     # of liveness analysis (i.e. they kill use chains)
     if isa(stmt, NewvarNode)
         result[slot_id(stmt.slot)].any_newvar = true

base/boot.jl

@@ -590,6 +590,7 @@ const undef = UndefInitializer()
 # empty vector constructor
 (self::Type{GenericMemory{kind,T,addrspace}})() where {T,kind,addrspace} = self(undef, 0)
 
+# memoryref is simply convenience wrapper function around memoryrefnew
 memoryref(mem::GenericMemory) = memoryrefnew(mem)
 memoryref(mem::GenericMemory, i::Integer) = memoryrefnew(memoryrefnew(mem), Int(i), @_boundscheck)
 memoryref(ref::GenericMemoryRef, i::Integer) = memoryrefnew(ref, Int(i), @_boundscheck)
@@ -744,17 +745,19 @@ let
 end
 
 # module providing the IR object model
+# excluding types already exported by Core (GlobalRef, QuoteNode, Expr, LineNumberNode)
+# any type beyond these is self-quoting (see also Base.is_ast_node)
 module IR
 
 export CodeInfo, MethodInstance, CodeInstance, GotoNode, GotoIfNot, ReturnNode,
     NewvarNode, SSAValue, SlotNumber, Argument,
     PiNode, PhiNode, PhiCNode, UpsilonNode, DebugInfo,
-    Const, PartialStruct, InterConditional, EnterNode, memoryref
+    Const, PartialStruct, InterConditional, EnterNode
 
 using Core: CodeInfo, MethodInstance, CodeInstance, GotoNode, GotoIfNot, ReturnNode,
     NewvarNode, SSAValue, SlotNumber, Argument,
     PiNode, PhiNode, PhiCNode, UpsilonNode, DebugInfo,
-    Const, PartialStruct, InterConditional, EnterNode, memoryref
+    Const, PartialStruct, InterConditional, EnterNode
 
 end # module IR
 

base/essentials.jl

@@ -1,6 +1,6 @@
 # This file is a part of Julia. License is MIT: https://julialang.org/license
 
-using Core: CodeInfo, SimpleVector, donotdelete, compilerbarrier, memoryrefnew, memoryrefget, memoryrefset!
+using Core: CodeInfo, SimpleVector, donotdelete, compilerbarrier, memoryref, memoryrefnew, memoryrefget, memoryrefset!
 
 const Callable = Union{Function,Type}
 

base/expr.jl

@@ -60,7 +60,8 @@ function copy(x::PhiCNode)
     return PhiCNode(new_values)
 end
 
-# copy parts of an AST that the compiler mutates
+# copy parts of an IR that the compiler mutates
+# (this is not a general-purpose copy for an Expr AST)
 function copy_exprs(@nospecialize(x))
     if isa(x, Expr)
         return copy(x)
@@ -91,10 +92,86 @@ function copy(c::CodeInfo)
     return cnew
 end
 
+function isequal_exprarg(@nospecialize(x), @nospecialize(y))
+    x isa typeof(y) || return false
+    x === y && return true
+    # c.f. list of types in copy_expr also
+    if x isa Expr
+        x == (y::Expr) && return true
+    elseif x isa QuoteNode
+        x == (y::QuoteNode) && return true
+    elseif x isa PhiNode
+        x == (y::PhiNode) && return true
+    elseif x isa PhiCNode
+        x == (y::PhiCNode) && return true
+    elseif x isa CodeInfo
+        x == (y::CodeInfo) && return true
+    end
+    return false
+end
+
+
+function isequal_exprargs(x::Array{Any,1}, y::Array{Any,1})
+    l = length(x)
+    l == length(y) || return false
+    for i = 1:l
+        if !isassigned(x, i)
+            # phi and phic values are permitted to be undef
+            isassigned(y, i) && return false
+        else
+            isassigned(y, i) || return false
+            isequal_exprarg(x[i], y[i]) || return false
+        end
+    end
+    return true
+end
+
+# define == such that == inputs to parsing (including line numbers) yield == outputs from lowering (including all metadata)
+# (aside from cases where parsing just returns a number, which are ambiguous here)
+==(x::Expr, y::Expr) = x.head === y.head && isequal_exprargs(x.args, y.args)
+
+==(x::QuoteNode, y::QuoteNode) = isequal_exprarg(x.value, y.value)
+
+==(stmt1::Core.PhiNode, stmt2::Core.PhiNode) = isequal(stmt1.edges, stmt2.edges) && isequal_exprargs(stmt1.values, stmt2.values)
+
+==(stmt1::Core.PhiCNode, stmt2::Core.PhiCNode) = isequal_exprargs(stmt1.values, stmt2.values)
+
+function ==(stmt1::CodeInfo, stmt2::CodeInfo)
+    for i in 1:nfields(stmt1)
+        if !isdefined(stmt1, i)
+            isdefined(stmt2, i) && return false
+        else
+            isdefined(stmt2, i) || return false
+            f1 = getfield(stmt1, i)
+            f2 = getfield(stmt2, i)
+            f1 isa typeof(f2) || return false
+            if f1 isa Vector{Any}
+                # code or types vectors
+                isequal_exprargs(f1, f2::Vector{Any}) || return false
+            elseif f1 isa DebugInfo
+                f1 == f2::DebugInfo || return false
+            elseif f1 isa Vector
+                # misc data
+                l = length(f1)
+                l == length(f2::Vector) || return false
+                for i = 1:l
+                    f1[i] === f2[i] || return false
+                end
+            else
+                # misc fields
+                f1 === f2 || return false
+            end
+        end
+    end
+    return true
+end
 
-==(x::Expr, y::Expr) = x.head === y.head && isequal(x.args, y.args)
-==(x::QuoteNode, y::QuoteNode) = isequal(x.value, y.value)
-==(stmt1::Core.PhiNode, stmt2::Core.PhiNode) = stmt1.edges == stmt2.edges && stmt1.values == stmt2.values
+function ==(x::DebugInfo, y::DebugInfo)
+    for i in 1:nfields(x)
+        getfield(x, i) == getfield(y, i) || return false
+    end
+    return true
+end
 
 """
     macroexpand(m::Module, x; recursive=true)
@@ -1662,14 +1739,45 @@ end
 is_meta_expr_head(head::Symbol) = head === :boundscheck || head === :meta || head === :loopinfo
 is_meta_expr(@nospecialize x) = isa(x, Expr) && is_meta_expr_head(x.head)
 
-function is_self_quoting(@nospecialize(x))
-    return isa(x,Number) || isa(x,AbstractString) || isa(x,Tuple) || isa(x,Type) ||
-        isa(x,Char) || x === nothing || isa(x,Function)
-end
+"""
+    isa_ast_node(x)
 
-function quoted(@nospecialize(x))
-    return is_self_quoting(x) ? x : QuoteNode(x)
-end
+Return false if `x` is not interpreted specially by any of inference, lowering,
+or codegen as either an AST or IR special form.
+"""
+function isa_ast_node(@nospecialize x)
+    # c.f. Core.IR module, augmented with AST types
+    return x isa NewvarNode ||
+           x isa CodeInfo ||
+           x isa LineNumberNode ||
+           x isa GotoNode ||
+           x isa GotoIfNot ||
+           x isa EnterNode ||
+           x isa ReturnNode ||
+           x isa SSAValue ||
+           x isa SlotNumber ||
+           x isa Argument ||
+           x isa QuoteNode ||
+           x isa GlobalRef ||
+           x isa Symbol ||
+           x isa PiNode ||
+           x isa PhiNode ||
+           x isa PhiCNode ||
+           x isa UpsilonNode ||
+           x isa Expr
+end
+
+is_self_quoting(@nospecialize(x)) = !isa_ast_node(x)
+
+"""
+    quoted(x)
+
+Return `x` made safe for inserting as a constant into IR. Note that this does
+not make it safe for inserting into an AST, since eval will sometimes copy some
+types of AST object inside, and even may sometimes evaluate and interpolate any
+`\$` inside, depending on the context.
+"""
+quoted(@nospecialize(x)) = isa_ast_node(x) ? QuoteNode(x) : x
 
 # Implementation of generated functions
 function generated_body_to_codeinfo(ex::Expr, defmod::Module, isva::Bool)

base/hashing.jl

@@ -232,11 +232,32 @@ end
 
 ## symbol & expression hashing ##
 if UInt === UInt64
+    # conservatively hash using == equality of all of the data, even though == often uses === internally
     hash(x::Expr, h::UInt) = hash(x.args, hash(x.head, h ⊻ 0x83c7900696d26dc6))
     hash(x::QuoteNode, h::UInt) = hash(x.value, h ⊻ 0x2c97bf8b3de87020)
+    hash(x::PhiNode, h::UInt) = hash(x.edges, hash(x.values, h ⊻ 0x2c97bf8b3de87020))
+    hash(x::PhiCNode, h::UInt) = hash(x.values, h ⊻ 0x2c97bf8b3de87020)
 else
     hash(x::Expr, h::UInt) = hash(x.args, hash(x.head, h ⊻ 0x469d72af))
     hash(x::QuoteNode, h::UInt) = hash(x.value, h ⊻ 0x469d72af)
+    hash(x::PhiNode, h::UInt) = hash(x.edges, hash(x.values, h ⊻ 0x469d72af))
+    hash(x::PhiCNode, h::UInt) = hash(x.values, h ⊻ 0x469d72af)
+end
+
+function hash(x::CodeInfo, h::UInt)
+    h ⊻= UInt === UInt64 ? 0x2c97bf8b3de87020 : 0x469d72af
+    for i in 1:nfields(x)
+        h = hash(isdefined(x, i) ? getfield(x, i) : missing, h)
+    end
+    return h
+end
+
+function hash(x::DebugInfo, h::UInt)
+    h ⊻= UInt === UInt64 ? 0x2c97bf8b3de87020 : 0x469d72af
+    for i in 1:nfields(x)
+        h = hash(getfield(x, i), h)
+    end
+    return h
 end
 
 hash(x::Symbol) = objectid(x)

base/public.jl

@@ -68,6 +68,11 @@ public
     ispublic,
     remove_linenums!,
 
+# AST handling
+    IR,
+    isa_ast_node,
+    quoted,
+
 # Operators
     operator_associativity,
     operator_precedence,

base/timing.jl

@@ -495,7 +495,7 @@ function is_simply_call(@nospecialize ex)
     for a in ex.args
         a isa QuoteNode && continue
         a isa Symbol && continue
-        Base.is_self_quoting(a) && continue
+        isa_ast_node(a) || continue
         return false
     end
     return true

doc/src/devdocs/builtins.md

@@ -41,4 +41,6 @@ Core.get_binding_type
 Core.IntrinsicFunction
 Core.Intrinsics
 Core.IR
+Base.quoted
+Base.isa_ast_node
 ```

doc/src/manual/metaprogramming.md

@@ -363,6 +363,14 @@ QuoteNode
 
 `QuoteNode` can also be used for certain advanced metaprogramming tasks.
 
+Note that while it does not support `$`, it also does not prevent it, nor does
+it preserve the identity of the wrapped object:
+
+```jldoctest
+julia> b = 2; eval(Expr(:quote, QuoteNode(Expr(:$, :b))))
+:($(QuoteNode(2)))
+```
+
 ### Evaluating expressions
 
 Given an expression object, one can cause Julia to evaluate (execute) it at global scope using

src/ast.c

@@ -1047,14 +1047,15 @@ int jl_has_meta(jl_array_t *body, jl_sym_t *sym) JL_NOTSAFEPOINT
 
 // Utility function to return whether `e` is any of the special AST types or
 // will always evaluate to itself exactly unchanged. This corresponds to
-// `is_self_quoting` in Core.Compiler utilities.
-int jl_is_ast_node(jl_value_t *e) JL_NOTSAFEPOINT
+// `isa_ast_node` in Core.Compiler utilities.
+int jl_isa_ast_node(jl_value_t *e) JL_NOTSAFEPOINT
 {
     return jl_is_newvarnode(e)
         || jl_is_code_info(e)
         || jl_is_linenode(e)
         || jl_is_gotonode(e)
         || jl_is_gotoifnot(e)
+        || jl_is_enternode(e)
         || jl_is_returnnode(e)
         || jl_is_ssavalue(e)
         || jl_is_slotnumber(e)
@@ -1069,9 +1070,10 @@ int jl_is_ast_node(jl_value_t *e) JL_NOTSAFEPOINT
         || jl_is_expr(e);
 }
 
-static int is_self_quoting_expr(jl_expr_t *e) JL_NOTSAFEPOINT
+static int is_self_escaping_expr(jl_expr_t *e) JL_NOTSAFEPOINT
 {
     return (e->head == jl_inert_sym ||
+            e->head == jl_leave_sym ||
             e->head == jl_core_sym ||
             e->head == jl_line_sym ||
             e->head == jl_lineinfo_sym ||
@@ -1089,12 +1091,13 @@ int need_esc_node(jl_value_t *e) JL_NOTSAFEPOINT
         || jl_is_ssavalue(e)
         || jl_is_slotnumber(e)
         || jl_is_argument(e)
+        || jl_is_enternode(e)
         || jl_is_quotenode(e))
         return 0;
     if (jl_is_expr(e))
-        return !is_self_quoting_expr((jl_expr_t*)e);
+        return !is_self_escaping_expr((jl_expr_t*)e);
     // note: jl_is_globalref(e) is not included here, since we care a little about about having a line number for it
-    return jl_is_ast_node(e);
+    return jl_isa_ast_node(e);
 }
 
 static jl_value_t *jl_invoke_julia_macro(jl_array_t *args, jl_module_t *inmodule, jl_module_t **ctx, jl_value_t **lineinfo, size_t world, int throw_load_error)