self-hosted: rework the memory layout of ir.Module and related types

 * add TypedValue.Managed which represents a Type, a Value, and some
   kind of memory management strategy.
 * introduce an analysis queue
 * flesh out how incremental compilation works with respect to exports
 * ir.text.Module is only capable of one error message during parsing
 * link.zig no longer has a decl table map and instead has structs that
   exist directly on ir.Module.Decl and ir.Module.Export
 * implement primitive .text block allocation
 * implement linker code for updating Decls and Exports
 * implement null Type

Some supporting std lib changes:
 * add std.ArrayList.appendSliceAssumeCapacity
 * add std.fs.File.copyRange and copyRangeAll
 * fix std.HashMap having modification safety on in ReleaseSmall builds
 * add std.HashMap.putAssumeCapacityNoClobber

1 files changed, 24 insertions, 0 deletions

diff --git a/lib/std/fs/file.zig b/lib/std/fs/file.zig
index b7c575a04a..a33d0d8e3e 100644
--- a/lib/std/fs/file.zig
+++ b/lib/std/fs/file.zig
@@ -527,6 +527,30 @@ pub const File = struct {
         }
     }
 
+    pub fn copyRange(in: File, in_offset: u64, out: File, out_offset: u64, len: usize) PWriteError!usize {
+        // TODO take advantage of copy_file_range OS APIs
+        var buf: [8 * 4096]u8 = undefined;
+        const adjusted_count = math.min(buf.len, len);
+        const amt_read = try in.pread(buf[0..adjusted_count], in_offset);
+        if (amt_read == 0) return 0;
+        return out.pwrite(buf[0..amt_read], out_offset);
+    }
+
+    /// Returns the number of bytes copied. If the number read is smaller than `buffer.len`, it
+    /// means the in file reached the end. Reaching the end of a file is not an error condition.
+    pub fn copyRangeAll(in: File, in_offset: u64, out: File, out_offset: u64, len: usize) PWriteError!usize {
+        var total_bytes_copied = 0;
+        var in_off = in_offset;
+        var out_off = out_offset;
+        while (total_bytes_copied < len) {
+            const amt_copied = try copyRange(in, in_off, out, out_off, len - total_bytes_copied);
+            if (amt_copied == 0) return total_bytes_copied;
+            total_bytes_copied += amt_copied;
+            in_off += amt_copied;
+            out_off += amt_copied;
+        }
+    }
+
     pub const WriteFileOptions = struct {
         in_offset: u64 = 0,