Handle clang/gcc defining "unix" during compilation (#121097)

The clang and gcc tool chains defines 'unix' during compilation - clang
doesn't on macOS. This means that during the data contract generation
the "unix" string was converted to "1" and interpreted as "windows". See
`./src/mono/browser/emsdk/emscripten/emcc -dM -E - < /dev/null | grep
unix` or `clang -dM -E - < /dev/null | grep unix` on a linux distro.

The first step is to create a specific OS for the browser and then make
all string definitions case sensitive so the "unix" define doesn't
convert. We also place some defensive checks in place for the OS names
that aren't all that unique either.

Author: AaronRobinsonMSFT

src/coreclr/vm/datadescriptor/datadescriptor.inc

@@ -989,10 +989,21 @@ CDAC_TYPES_END()
 
 CDAC_GLOBALS_BEGIN()
 
-#if defined(TARGET_UNIX)
-CDAC_GLOBAL_STRING(OperatingSystem, unix)
+#if defined(TARGET_BROWSER)
+#ifdef Browser
+#error Handle 'Browser' define
+#endif // Browser
+CDAC_GLOBAL_STRING(OperatingSystem, Browser)
+#elif defined(TARGET_UNIX)
+#ifdef Unix
+#error Handle 'Unix' define
+#endif // Unix
+CDAC_GLOBAL_STRING(OperatingSystem, Unix)
 #elif defined(TARGET_WINDOWS)
-CDAC_GLOBAL_STRING(OperatingSystem, windows)
+#ifdef Windows
+#error Handle 'Windows' define
+#endif // Windows
+CDAC_GLOBAL_STRING(OperatingSystem, Windows)
 #else
 #error TARGET_{OS} define is not recognized by the cDAC. Update this switch and the enum values in IRuntimeInfo.cs
 #endif

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeInfo.cs

@@ -26,6 +26,7 @@ public enum RuntimeInfoOperatingSystem : uint
     Unknown = 0,
     Windows,
     Unix,
+    Browser,
 }
 
 public interface IRuntimeInfo : IContract

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/AMD64/AMD64Unwinder.cs

@@ -31,7 +31,7 @@ internal class AMD64Unwinder(Target target)
     private readonly Target _target = target;
     private readonly IExecutionManager _eman = target.Contracts.ExecutionManager;
 
-    private readonly bool _unix = target.Contracts.RuntimeInfo.GetTargetOperatingSystem() == RuntimeInfoOperatingSystem.Unix;
+    private readonly bool _unixAMD64ABI = target.Contracts.RuntimeInfo.GetTargetOperatingSystem() != RuntimeInfoOperatingSystem.Windows;
 
     public bool Unwind(ref AMD64Context context)
     {
@@ -97,7 +97,7 @@ public bool Unwind(ref AMD64Context context)
         {
             frameOffset = unwindInfo.FrameOffset;
 
-            if (_unix)
+            if (_unixAMD64ABI)
             {
                 // If UnwindInfo->FrameOffset == 15 (the maximum value), then there might be a UWOP_SET_FPREG_LARGE.
                 // However, it is still legal for a UWOP_SET_FPREG to set UnwindInfo->FrameOffset == 15 (since this
@@ -133,7 +133,7 @@ public bool Unwind(ref AMD64Context context)
                 unwindOp = GetUnwindCode(unwindInfo, index);
                 if (unwindOp.UnwindOp == UnwindCode.OpCodes.UWOP_SET_FPREG)
                     break;
-                if (_unix)
+                if (_unixAMD64ABI)
                 {
                     if (unwindOp.UnwindOp == UnwindCode.OpCodes.UWOP_SET_FPREG_LARGE)
                     {
@@ -835,7 +835,7 @@ private bool UnwindPrologue(
 
                 UnwindCode unwindOp = GetUnwindCode(unwindInfo, index);
 
-                if (_unix)
+                if (_unixAMD64ABI)
                 {
                     if (unwindOp.UnwindOp > UnwindCode.OpCodes.UWOP_SET_FPREG_LARGE)
                     {
@@ -845,7 +845,8 @@ private bool UnwindPrologue(
                 }
                 else
                 {
-                    if (unwindOp.UnwindOp == UnwindCode.OpCodes.UWOP_SET_FPREG_LARGE)
+                    Debug.Assert(_target.Contracts.RuntimeInfo.GetTargetOperatingSystem() == RuntimeInfoOperatingSystem.Windows);
+                    if (unwindOp.UnwindOp > UnwindCode.OpCodes.UWOP_PUSH_MACHFRAME)
                     {
                         Debug.Fail("Expected unwind code");
                         return false;
@@ -929,7 +930,7 @@ private bool UnwindPrologue(
                         //
                         case UnwindCode.OpCodes.UWOP_SET_FPREG_LARGE:
                             {
-                                UnwinderAssert(_unix);
+                                UnwinderAssert(_unixAMD64ABI);
                                 UnwinderAssert(unwindInfo.FrameOffset == 15);
                                 uint frameOffset = GetUnwindCode(unwindInfo, index + 1).FrameOffset;
                                 frameOffset += (uint)(GetUnwindCode(unwindInfo, index + 2).FrameOffset << 16);

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/X86/X86Unwinder.cs

@@ -34,7 +34,7 @@ public class X86Unwinder(Target target)
     private readonly Target _target = target;
     private readonly uint _pointerSize = (uint)target.PointerSize;
     private readonly bool _updateAllRegs = true;
-    private readonly bool _unixX86ABI = target.Contracts.RuntimeInfo.GetTargetOperatingSystem() == RuntimeInfoOperatingSystem.Unix;
+    private readonly bool _unixX86ABI = target.Contracts.RuntimeInfo.GetTargetOperatingSystem() != RuntimeInfoOperatingSystem.Windows;
 
     private static readonly RegMask[] registerOrder =
     [

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/SOSDacImpl.cs

@@ -589,9 +589,10 @@ int ISOSDacInterface.GetClrWatsonBuckets(ClrDataAddress thread, void* pGenericMo
         byte[] buckets = Array.Empty<byte>();
         try
         {
-            if (_target.Contracts.RuntimeInfo.GetTargetOperatingSystem() == RuntimeInfoOperatingSystem.Unix)
+            if (_target.Contracts.RuntimeInfo.GetTargetOperatingSystem() != RuntimeInfoOperatingSystem.Windows)
                 throw Marshal.GetExceptionForHR(HResults.E_FAIL)!;
-            else if (thread == 0 || pGenericModeBlock == null)
+
+            if (thread == 0 || pGenericModeBlock == null)
                 throw new ArgumentException();
 
             buckets = threadContract.GetWatsonBuckets(thread.ToTargetPointer(_target));