<div dir="ltr"><br><br><div class="gmail_quote"><div dir="ltr">On Tue, Nov 13, 2018 at 11:46 AM Davide Italiano via lldb-commits <<a href="mailto:lldb-commits@lists.llvm.org">lldb-commits@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: davide<br>
Date: Tue Nov 13 11:43:43 2018<br>
New Revision: 346783<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=346783&view=rev" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project?rev=346783&view=rev</a><br>
Log:<br>
[Cocoa] Implement formatter for the new NSDate representation.<br>
<br>
<rdar://problem/46002786><br>
<br>
Modified:<br>
    lldb/trunk/source/Plugins/Language/ObjC/Cocoa.cpp<br>
<br>
Modified: lldb/trunk/source/Plugins/Language/ObjC/Cocoa.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/Language/ObjC/Cocoa.cpp?rev=346783&r1=346782&r2=346783&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/Language/ObjC/Cocoa.cpp?rev=346783&r1=346782&r2=346783&view=diff</a><br>
==============================================================================<br>
--- lldb/trunk/source/Plugins/Language/ObjC/Cocoa.cpp (original)<br>
+++ lldb/trunk/source/Plugins/Language/ObjC/Cocoa.cpp Tue Nov 13 11:43:43 2018<br>
@@ -742,6 +742,60 @@ bool lldb_private::formatters::NSURLSumm<br>
   return false;<br>
 }<br>
<br>
+/// Bias value for tagged pointer exponents.<br>
+/// Recommended values:<br>
+/// 0x3e3: encodes all dates between distantPast and distantFuture<br>
+///   except for the range within about 1e-28 second of the reference date.<br>
+/// 0x3ef: encodes all dates for a few million years beyond distantPast and<br>
+///   distantFuture, except within about 1e-25 second of the reference date.<br>
+const int TAGGED_DATE_EXPONENT_BIAS = 0x3ef;<br>
+<br>
+typedef union {<br>
+  struct {<br>
+    uint64_t fraction:52;  // unsigned<br>
+    uint64_t exponent:11;  // signed<br>
+    uint64_t sign:1;<br>
+  };<br>
+  uint64_t i;<br>
+  double d;<br>
+} DoubleBits;<br>
+typedef union {<br>
+  struct {<br>
+    uint64_t fraction:52;  // unsigned<br>
+    uint64_t exponent:7;   // signed<br>
+    uint64_t sign:1;<br>
+    uint64_t unused:4;  // placeholder for pointer tag bits<br>
+  };<br></blockquote><div>MSVC gives:</div><div><br></div><div>warning C4201: nonstandard extension used: nameless struct/union</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
+  uint64_t i;<br>
+} TaggedDoubleBits;<br>
+<br>
+static uint64_t decodeExponent(uint64_t exp) {<br>
+  int64_t exp7 = exp;<br>
+  // Tagged exponent field is 7-bit signed. Sign-extend the value to 64 bits<br>
+  // before performing arithmetic.<br>
+  int64_t exp11 = ((exp7 << 57) >> 57) + TAGGED_DATE_EXPONENT_BIAS;<br>
+  return exp11;<br>
+}<br></blockquote><div>this should probably be:</div><div><br></div><div>return llvm::SignExtend64<7>(exp) + TAGGED_DATE_EXPONENT_BIAS;</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
+<br>
+static uint64_t decodeTaggedTimeInterval(uint64_t encodedTimeInterval) {<br>
+  if (encodedTimeInterval == 0)<br>
+    return 0.0;<br>
+  if (encodedTimeInterval == std::numeric_limits<uint64_t>::max())<br>
+    return -0.0;<br>
+<br>
+  TaggedDoubleBits encodedBits = { .i = encodedTimeInterval };<br></blockquote><div>Designated initializers are C++20 which are not allowed in LLVM.</div></div></div>