reconstruct map the hardway before 1.13

Author: vchuravy

src/jlgen.jl

@@ -672,6 +672,28 @@ end
     CompilationPolicyExtern = 1
 end
 
+const AL_N_INLINE = 29
+# mirrows arraylist_t
+mutable struct ArrayList
+    len::Csize_t
+    max::Csize_t
+    items::Ptr{Ptr{Cvoid}}
+    _space::NTuple{AL_N_INLINE, Ptr{Cvoid}}
+
+    function ArrayList()
+        list = new(0, AL_N_INLINE, Ptr{Ptr{Cvoid}}(C_NULL), ntuple(_->Ptr{Cvoid}(C_NULL), AL_N_INLINE))
+        list.items = Base.pointer_from_objref(list) + fieldoffset(typeof(list), 4)
+
+        finalizer(list) do list
+            if list.items != Base.pointer_from_objref(list) + fieldoffset(typeof(list), 4)
+                Libc.free(list.items)
+            end
+        end
+        return list
+    end
+end
+
+
 """
     precompile(job::CompilerJob)
 
@@ -787,16 +809,17 @@ function compile_method_instance(@nospecialize(job::CompilerJob))
     end
 
     gv_to_value = Dict{String, Any}()
-    num_gvars = Ref{Csize_t}(0)
-    @ccall jl_get_llvm_gvs(native_code::Ptr{Cvoid}, num_gvars::Ptr{Csize_t},
-                           C_NULL::Ptr{Cvoid})::Nothing
-    gvs = Vector{Ptr{LLVM.API.LLVMOpaqueValue}}(undef, num_gvars[])
-    @ccall jl_get_llvm_gvs(native_code::Ptr{Cvoid}, num_gvars::Ptr{Csize_t},
-                           gvs::Ptr{LLVM.API.LLVMOpaqueValue})::Nothing
 
     if VERSION >= v"1.13.0-DEV.623"
         # Since Julia 1.13, the caller is responsible for initializing global variables that
         # point to global values or bindings with their address in memory.
+        num_gvars = Ref{Csize_t}(0)
+        @ccall jl_get_llvm_gvs(native_code::Ptr{Cvoid}, num_gvars::Ptr{Csize_t},
+                           C_NULL::Ptr{Cvoid})::Nothing
+        gvs = Vector{Ptr{LLVM.API.LLVMOpaqueValue}}(undef, num_gvars[])
+        @ccall jl_get_llvm_gvs(native_code::Ptr{Cvoid}, num_gvars::Ptr{Csize_t},
+                           gvs::Ptr{LLVM.API.LLVMOpaqueValue})::Nothing
+
         inits = Vector{Ptr{Cvoid}}(undef, num_gvars[])
         @ccall jl_get_llvm_gv_inits(native_code::Ptr{Cvoid}, num_gvars::Ptr{Csize_t},
                                     inits::Ptr{Cvoid})::Nothing
@@ -807,15 +830,50 @@ function compile_method_instance(@nospecialize(job::CompilerJob))
             initializer!(gv, val)
 
             # TODO: jl_binding_t?
+            @show LLVM.name(gv), val
             gv_to_value[LLVM.name(gv)] = Base.unsafe_pointer_to_objref(val)
         end
     else
-        for gv_ref in gvs
-            gv = GlobalVariable(gv_ref)
-            val = reinterpret(Ptr{Cvoid}, initializer(gv))
-            # TODO: jl_binding_t?
-            gv_to_value[LLVM.name(gv)] = Base.unsafe_pointer_to_objref(val)
+        # Prior to this version of Julia we only had access to the values that the global variables
+        # were initialized with, so we have to match them up manually.
+        # get the global values
+        if VERSION >= v"1.12.0-DEV.1703"
+            num_gvars = Ref{Csize_t}(0)
+            @ccall jl_get_llvm_gvs(native_code::Ptr{Cvoid}, num_gvars::Ptr{Csize_t},
+                            C_NULL::Ptr{Cvoid})::Nothing
+            gvalues = Vector{Ptr{Cvoid}}(undef, num_gvars[])
+            @ccall jl_get_llvm_gvs(native_code::Ptr{Cvoid}, num_gvars::Ptr{Csize_t},
+                            gvalues::Ptr{Cvoid})::Nothing
+        else
+            # Sigh on older version of Julia we have to use `arraylist_t` which doesn't have a Julia API.
+            gvars = ArrayList()
+            GC.@preserve gvars begin
+                p_gvars = Base.pointer_from_objref(gvars)
+                @ccall jl_get_llvm_gvs(native_code::Ptr{Cvoid}, p_gvars::Ptr{Cvoid})::Nothing
+                gvalues = Vector{Ptr{Cvoid}}(undef, gvars.len)
+                for i in 1:gvars.len
+                    gvalues[i] = unsafe_load(gvars.items, i)
+                end
+            end
+        end
+        gvalues = Set(gvalues)
+        for gv in globals(llvm_mod)
+            init = LLVM.initializer(gv)
+            if init === nothing
+                continue
+            end
+            if init isa LLVM.ConstantExpr && opcode(init) == LLVM.API.LLVMIntToPtr
+                init = operands(init)[1]
+            end
+            if !(init isa LLVM.ConstantInt)
+                continue
+            end
+            ptr = reinterpret(Ptr{Cvoid}, convert(UInt, init))
+            if ptr in gvalues
+                gv_to_value[LLVM.name(gv)] = Base.unsafe_pointer_to_objref(ptr)
+            end
         end
+        @assert length(gv_to_value) == length(gvalues)
     end
 
     if VERSION >= v"1.13.0-DEV.1120"