rt.sections_osx_x86_64: Refactor & move a helper to rt.sections_darwin_64

That's the only functionality LDC needs from that module, the other
helpers used by LDC for 64-bit Darwin (not just for x86_64, but also
AArch64) already reside in rt.sections_darwin_64.

Author: kinke

src/rt/sections_darwin_64.d

@@ -11,10 +11,6 @@
  */
 module rt.sections_darwin_64;
 
-import core.sys.darwin.mach.dyld;
-import core.sys.darwin.mach.getsect;
-import core.sys.posix.pthread;
-
 version (OSX)
     version = Darwin;
 else version (iOS)
@@ -27,6 +23,12 @@ else version (WatchOS)
 version (Darwin):
 version (D_LP64):
 
+import core.sys.darwin.mach.dyld;
+import core.sys.darwin.mach.getsect;
+import core.sys.posix.pthread;
+
+import rt.util.utility : safeAssert;
+
 extern (C) size_t malloc_size(const void* ptr) nothrow @nogc;
 
 /**
@@ -176,3 +178,28 @@ const(section_64)[] sections(const segment_command_64* segment) pure nothrow @no
     const firstSection = cast(const(section_64)*)(cast(ubyte*) segment + size);
     return firstSection[0 .. segment.nsects];
 }
+
+/// Invokes the specified delegate for each (non-empty) data section.
+void foreachDataSection(in mach_header* header, intptr_t slide,
+                        scope void delegate(void[] sectionData) processor)
+{
+    foreach (section; [ SECT_DATA, SECT_BSS, SECT_COMMON ])
+    {
+        auto data = getSection(header, slide, SEG_DATA.ptr, section.ptr);
+        if (data !is null)
+            processor(data);
+    }
+}
+
+/// Returns a section's memory range, or null if not found or empty.
+void[] getSection(in mach_header* header, intptr_t slide,
+                  in char* segmentName, in char* sectionName)
+{
+    safeAssert(header.magic == MH_MAGIC_64, "Unsupported header.");
+    auto sect = getsectbynamefromheader_64(cast(mach_header_64*) header,
+                                           segmentName, sectionName);
+
+    if (sect !is null && sect.size > 0)
+        return (cast(void*)sect.addr + slide)[0 .. cast(size_t) sect.size];
+    return null;
+}

src/rt/sections_osx_x86_64.d

@@ -30,10 +30,11 @@ import core.sys.posix.pthread;
 import core.sys.darwin.mach.dyld;
 import core.sys.darwin.mach.getsect;
 
-import rt.deh, rt.minfo;
+import rt.deh;
+import rt.minfo;
+import rt.sections_darwin_64;
 import rt.util.container.array;
 import rt.util.utility : safeAssert;
-import rt.sections_darwin_64 : getTLSRange;
 
 struct SectionGroup
 {
@@ -121,12 +122,7 @@ __gshared SectionGroup _sections;
 
 extern (C) void sections_osx_onAddImage(const scope mach_header* h, intptr_t slide)
 {
-    foreach (e; dataSegs)
-    {
-        auto sect = getSection(h, slide, e.seg.ptr, e.sect.ptr);
-        if (sect != null)
-            _sections._gcRanges.insertBack((cast(void*)sect.ptr)[0 .. sect.length]);
-    }
+    foreachDataSection(h, slide, (sectionData) { _sections._gcRanges.insertBack(sectionData); });
 
     auto minfosect = getSection(h, slide, "__DATA", "__minfodata");
     if (minfosect != null)
@@ -160,26 +156,3 @@ extern (C) void sections_osx_onAddImage(const scope mach_header* h, intptr_t sli
         _sections._ehTables = p[0 .. len];
     }
 }
-
-struct SegRef
-{
-    string seg;
-    string sect;
-}
-
-static immutable SegRef[] dataSegs = [{SEG_DATA, SECT_DATA},
-                                      {SEG_DATA, SECT_BSS},
-                                      {SEG_DATA, SECT_COMMON}];
-
-ubyte[] getSection(in mach_header* header, intptr_t slide,
-                   in char* segmentName, in char* sectionName)
-{
-    safeAssert(header.magic == MH_MAGIC_64, "Unsupported header.");
-    auto sect = getsectbynamefromheader_64(cast(mach_header_64*)header,
-                                        segmentName,
-                                        sectionName);
-
-    if (sect !is null && sect.size > 0)
-        return (cast(ubyte*)sect.addr + slide)[0 .. cast(size_t)sect.size];
-    return null;
-}