Improve global value metadata accessors. (#513)

Author: maleadt

src/core/metadata.jl

@@ -250,11 +250,9 @@ metadata(::Union{Instruction, GlobalObject})
                MD_section_prefix = 20,
                MD_absolute_symbol = 21,
                MD_associated = 22)
-MDKind(name::String) = API.LLVMGetMDKindIDInContext(context(), name, length(name))
+MDKind(name::String) = MDKind(API.LLVMGetMDKindIDInContext(context(), name, length(name)))
 MDKind(kind::MDKind) = kind
 
-# XXX: automatically converting string keys to MDKind is too automagical
-
 # instructions (using MetadataAsValue values)
 
 # TODO: doesn't actually iterate, since we can't list the available keys
@@ -325,6 +323,23 @@ end
 Base.setindex!(md::GlobalMetadataDict, node::Metadata, key) =
     API.LLVMGlobalSetMetadata(md.val, MDKind(key), node)
 
+Base.get(md::GlobalMetadataDict, key, default) = get(md, MDKind(key), default)
+function Base.get(md::GlobalMetadataDict, key::MDKind, default)
+    for (k, v) in md
+        if k == key
+            return v
+        end
+    end
+    return default
+end
+
+Base.haskey(md::GlobalMetadataDict, key) = get(md, key, nothing) !== nothing
+function Base.getindex(md::GlobalMetadataDict, key)
+    val = get(md, key, nothing)
+    val === nothing && throw(KeyError(key))
+    return val
+end
+
 Base.delete!(md::GlobalMetadataDict, key) =
     API.LLVMGlobalEraseMetadata(md.val, MDKind(key))
 

test/core_tests.jl

@@ -797,13 +797,20 @@ end
     alignment!(fn, 4)
     @test alignment(fn) == 4
 
-    @test isempty(metadata(fn))
     str = MDString("bar")
     md = MDNode([str])
+    @test isempty(metadata(fn))
+    @test !haskey(metadata(fn), "foo")
+    @test_throws KeyError metadata(fn)["foo"]
     metadata(fn)["foo"] = md
     @test !isempty(metadata(fn))
-    # XXX: keyset contains raw MDKinds
+    @test haskey(metadata(fn), "foo")
+    @test metadata(fn)["foo"] == md
     @test collect(values(metadata(fn))) == [md]
+    delete!(metadata(fn), "foo")
+    @test isempty(metadata(fn))
+    metadata(fn)["foo"] = md
+    @test !isempty(metadata(fn))
     empty!(metadata(fn))
     @test isempty(metadata(fn))
 end