Merge pull request #33724 from JuliaLang/jn/layout-reorg

datatype: reorganize layout calculation code
JuliaLang · Nov 18, 2019 · 1e39c69 · 1e39c69 · nanosoldier · Nov 19, 2019
2 parents 05a80e1 + 4e0d353
commit 1e39c69
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Showing 10 changed files with 292 additions and 297 deletions.
diff --git a/base/reflection.jl b/base/reflection.jl
@@ -317,10 +317,10 @@ datatype_fieldtypes(x::DataType) = ccall(:jl_get_fieldtypes, Any, (Any,), x)
 
 struct DataTypeLayout
     nfields::UInt32
+    npointers::UInt32
     alignment::UInt32
-    # alignment : 28;
+    # alignment : 9;
     # haspadding : 1;
-    # pointerfree : 1;
     # fielddesc_type : 2;
 end
 
@@ -380,8 +380,8 @@ Can be called on any `isconcretetype`.
 function datatype_pointerfree(dt::DataType)
     @_pure_meta
     dt.layout == C_NULL && throw(UndefRefError())
-    alignment = unsafe_load(convert(Ptr{DataTypeLayout}, dt.layout)).alignment
-    return (alignment >> 10) & 0xFFFFF == 0
+    npointers = unsafe_load(convert(Ptr{DataTypeLayout}, dt.layout)).npointers
+    return npointers == 0
 end
 
 """
@@ -397,7 +397,7 @@ function datatype_fielddesc_type(dt::DataType)
     @_pure_meta
     dt.layout == C_NULL && throw(UndefRefError())
     alignment = unsafe_load(convert(Ptr{DataTypeLayout}, dt.layout)).alignment
-    return (alignment >> 30) & 3
+    return (alignment >> 10) & 3
 end
 
 """