Enable users to map from GV to Julia value

Author: vchuravy

src/driver.jl

@@ -197,7 +197,7 @@ const __llvm_initialized = Ref(false)
     end
 
     @tracepoint "IR generation" begin
-        ir, compiled = irgen(job)
+        ir, compiled, gv_to_value = irgen(job)
         if job.config.entry_abi === :specfunc
             entry_fn = compiled[job.source].specfunc
         else
@@ -422,7 +422,7 @@ const __llvm_initialized = Ref(false)
         @tracepoint "verification" verify(ir)
     end
 
-    return ir, (; entry, compiled)
+    return ir, (; entry, compiled, gv_to_value)
 end
 
 @locked function emit_asm(@nospecialize(job::CompilerJob), ir::LLVM.Module,

src/irgen.jl

@@ -1,7 +1,7 @@
 # LLVM IR generation
 
 function irgen(@nospecialize(job::CompilerJob))
-    mod, compiled = @tracepoint "emission" compile_method_instance(job)
+    mod, compiled, gv_to_value = @tracepoint "emission" compile_method_instance(job)
     if job.config.entry_abi === :specfunc
         entry_fn = compiled[job.source].specfunc
     else
@@ -120,7 +120,9 @@ function irgen(@nospecialize(job::CompilerJob))
         can_throw(job) || lower_throw!(mod)
     end
 
-    return mod, compiled
+    # TODO: should we filter out non-preserved_gvs?
+
+    return mod, compiled, gv_to_value
 end
 
 

src/jlgen.jl

@@ -786,15 +786,17 @@ function compile_method_instance(@nospecialize(job::CompilerJob))
         cache_gbl = nothing
     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
@@ -803,6 +805,16 @@ function compile_method_instance(@nospecialize(job::CompilerJob))
             gv = GlobalVariable(gv_ref)
             val = const_inttoptr(ConstantInt(Int64(init)), LLVM.PointerType())
             initializer!(gv, val)
+
+            # TODO: jl_binding_t?
+            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)
         end
     end
 
@@ -874,7 +886,7 @@ function compile_method_instance(@nospecialize(job::CompilerJob))
     # ensure that the requested method instance was compiled
     @assert haskey(compiled, job.source)
 
-    return llvm_mod, compiled
+    return llvm_mod, compiled, gv_to_value
 end
 
 # partially revert JuliaLangjulia#49391