From 07a25c9ec1deb7bcdf45d37d51a5b18d91fd1083 Mon Sep 17 00:00:00 2001
From: Rainer Schuetze <r.sagitario@gmx.de>
Date: Sun, 27 Aug 2017 18:14:58 +0200
Subject: [PATCH 1/2] fix issue 17788: MSCOFF: with VS2017 15.3.1 segment .tls
 is no longer written to a separate image section, so _tls_start and _tls_end
 no longer happen to work as both __gshared and TLS section offsets.

---
 src/rt/sections_win64.d | 47 +++++++++++++++++++++++++++++++----------
 1 file changed, 36 insertions(+), 11 deletions(-)

diff --git a/src/rt/sections_win64.d b/src/rt/sections_win64.d
index 92bafc8b82..8d81e50904 100644
--- a/src/rt/sections_win64.d
+++ b/src/rt/sections_win64.d
@@ -108,12 +108,40 @@ void finiSections() nothrow @nogc
     .free(_sections._gcRanges.ptr);
 }
 
-void[] initTLSRanges() nothrow @nogc
-{
-    auto pbeg = cast(void*)&_tls_start;
-    auto pend = cast(void*)&_tls_end;
-    return pbeg[0 .. pend - pbeg];
-}
+void[] initTLSRanges() nothrow @nogc
+{
+    void* pbeg;
+    void* pend;
+    version(Win32)
+    {
+        asm @nogc nothrow
+        {
+            mov EAX, _tls_index;
+            mov ECX, FS:[0x2C];     // _tls_array
+            mov EAX, [ECX+4*EAX];
+            mov pbeg, EAX;
+            add EAX, [_tls_used+4]; // end
+            sub EAX, [_tls_used+0]; // start
+            mov pend, EAX;
+        }
+    }
+    else
+    {
+        asm @nogc nothrow
+        {
+            xor RAX, RAX;
+            mov EAX, _tls_index;
+            mov RCX, 0x58;
+            mov RCX, GS:[RCX]; // _tls_array (immediate value causes fixup)
+            mov RAX, [RCX+8*RAX];
+            mov pbeg, RAX;
+            add RAX, [_tls_used+8]; // end
+            sub RAX, [_tls_used+0]; // start
+            mov pend, RAX;
+        }
+    }
+    return pbeg[0 .. pend - pbeg];
+}
 
 void finiTLSRanges(void[] rng) nothrow @nogc
 {
@@ -198,12 +226,9 @@ extern(C)
         uint _DP_end;
         uint _TP_beg;
         uint _TP_end;
-    }
 
-    extern
-    {
-        int _tls_start;
-        int _tls_end;
+        void*[2] _tls_used; // start, end
+        int _tls_index;
     }
 }
 

From 9676365f661bb3af8eda567151cbe5379acc62e6 Mon Sep 17 00:00:00 2001
From: Rainer Schuetze <r.sagitario@gmx.de>
Date: Mon, 28 Aug 2017 09:03:02 +0200
Subject: [PATCH 2/2] fix ws, add comment, use D_InlineAsm versions

---
 src/rt/sections_win64.d | 80 ++++++++++++++++++++++-------------------
 1 file changed, 44 insertions(+), 36 deletions(-)

diff --git a/src/rt/sections_win64.d b/src/rt/sections_win64.d
index 8d81e50904..8b5f53f4f3 100644
--- a/src/rt/sections_win64.d
+++ b/src/rt/sections_win64.d
@@ -108,40 +108,48 @@ void finiSections() nothrow @nogc
     .free(_sections._gcRanges.ptr);
 }
 
-void[] initTLSRanges() nothrow @nogc
-{
-    void* pbeg;
-    void* pend;
-    version(Win32)
-    {
-        asm @nogc nothrow
-        {
-            mov EAX, _tls_index;
-            mov ECX, FS:[0x2C];     // _tls_array
-            mov EAX, [ECX+4*EAX];
-            mov pbeg, EAX;
-            add EAX, [_tls_used+4]; // end
-            sub EAX, [_tls_used+0]; // start
-            mov pend, EAX;
-        }
-    }
-    else
-    {
-        asm @nogc nothrow
-        {
-            xor RAX, RAX;
-            mov EAX, _tls_index;
-            mov RCX, 0x58;
-            mov RCX, GS:[RCX]; // _tls_array (immediate value causes fixup)
-            mov RAX, [RCX+8*RAX];
-            mov pbeg, RAX;
-            add RAX, [_tls_used+8]; // end
-            sub RAX, [_tls_used+0]; // start
-            mov pend, RAX;
-        }
-    }
-    return pbeg[0 .. pend - pbeg];
-}
+void[] initTLSRanges() nothrow @nogc
+{
+    void* pbeg;
+    void* pend;
+    // with VS2017 15.3.1, the linker no longer puts TLS segments into a
+    //  separate image section. That way _tls_start and _tls_end no
+    //  longer generate offsets into .tls, but DATA.
+    // Use the TEB entry to find the start of TLS instead and read the
+    //  length from the TLS directory
+    version(D_InlineAsm_X86)
+    {
+        asm @nogc nothrow
+        {
+            mov EAX, _tls_index;
+            mov ECX, FS:[0x2C];     // _tls_array
+            mov EAX, [ECX+4*EAX];
+            mov pbeg, EAX;
+            add EAX, [_tls_used+4]; // end
+            sub EAX, [_tls_used+0]; // start
+            mov pend, EAX;
+        }
+    }
+    else version(D_InlineAsm_X86_64)
+    {
+        asm @nogc nothrow
+        {
+            xor RAX, RAX;
+            mov EAX, _tls_index;
+            mov RCX, 0x58;
+            mov RCX, GS:[RCX];      // _tls_array (immediate value causes fixup)
+            mov RAX, [RCX+8*RAX];
+            mov pbeg, RAX;
+            add RAX, [_tls_used+8]; // end
+            sub RAX, [_tls_used+0]; // start
+            mov pend, RAX;
+        }
+    }
+    else
+        static assert(false, "Architecture not supported.");
+
+    return pbeg[0 .. pend - pbeg];
+}
 
 void finiTLSRanges(void[] rng) nothrow @nogc
 {
@@ -227,8 +235,8 @@ extern(C)
         uint _TP_beg;
         uint _TP_end;
 
-        void*[2] _tls_used; // start, end
-        int _tls_index;
+        void*[2] _tls_used; // start, end
+        int _tls_index;
     }
 }