Fix method context number seen by the jit with parallel SPMI (#51753)

The jit can see the SPMI method context number by querying the
jit host for `SuperPMIMethodContextNumber`. Update the way this
value is computed, so it gives the same answer when running SPMI
in parallel that it does when running serially.

Author: AndyAyersMS

src/coreclr/ToolBox/superpmi/superpmi-shared/methodcontext.cpp

@@ -180,24 +180,24 @@ unsigned int MethodContext::saveToFile(HANDLE hFile)
 // (and sets *ppmc with new MethodContext), false on failure.
 //
 // static
-bool MethodContext::Initialize(int loadedCount, unsigned char* buff, DWORD size, /* OUT */ MethodContext** ppmc)
+bool MethodContext::Initialize(int mcIndex, unsigned char* buff, DWORD size, /* OUT */ MethodContext** ppmc)
 {
     MethodContext* mc = new MethodContext();
-    mc->index         = loadedCount;
+    mc->index         = mcIndex;
     *ppmc             = mc;
-    return mc->Initialize(loadedCount, buff, size);
+    return mc->Initialize(mcIndex, buff, size);
 }
 
 // static
-bool MethodContext::Initialize(int loadedCount, HANDLE hFile, /* OUT */ MethodContext** ppmc)
+bool MethodContext::Initialize(int mcIndex, HANDLE hFile, /* OUT */ MethodContext** ppmc)
 {
     MethodContext* mc = new MethodContext();
-    mc->index         = loadedCount;
+    mc->index         = mcIndex;
     *ppmc             = mc;
-    return mc->Initialize(loadedCount, hFile);
+    return mc->Initialize(mcIndex, hFile);
 }
 
-bool MethodContext::Initialize(int loadedCount, unsigned char* buff, DWORD size)
+bool MethodContext::Initialize(int mcIndex, unsigned char* buff, DWORD size)
 {
     bool result = true;
 
@@ -217,15 +217,15 @@ bool MethodContext::Initialize(int loadedCount, unsigned char* buff, DWORD size)
     }
     PAL_EXCEPT_FILTER(FilterSuperPMIExceptions_CatchMC)
     {
-        LogError("Method %d is of low integrity.", loadedCount);
+        LogError("Method %d is of low integrity.", mcIndex);
         result = false;
     }
     PAL_ENDTRY
 
     return result;
 }
 
-bool MethodContext::Initialize(int loadedCount, HANDLE hFile)
+bool MethodContext::Initialize(int mcIndex, HANDLE hFile)
 {
     bool result = true;
 
@@ -243,7 +243,7 @@ bool MethodContext::Initialize(int loadedCount, HANDLE hFile)
     }
     PAL_EXCEPT_FILTER(FilterSuperPMIExceptions_CatchMC)
     {
-        LogError("Method %d is of low integrity.", loadedCount);
+        LogError("Method %d is of low integrity.", mcIndex);
         result = false;
     }
     PAL_ENDTRY

src/coreclr/ToolBox/superpmi/superpmi-shared/methodcontext.h

@@ -72,14 +72,14 @@ class MethodContext
     void MethodInitHelper(unsigned char* buff, unsigned int totalLen);
     void MethodInitHelperFile(HANDLE hFile);
 
-    bool Initialize(int loadedCount, unsigned char* buff, DWORD size);
-    bool Initialize(int loadedCount, HANDLE hFile);
+    bool Initialize(int mcIndex, unsigned char* buff, DWORD size);
+    bool Initialize(int mcIndex, HANDLE hFile);
 
     int dumpMD5HashToBuffer(BYTE* pBuffer, int bufLen, char* buff, int len);
 
 public:
-    static bool Initialize(int loadedCount, unsigned char* buff, DWORD size, /* OUT */ MethodContext** ppmc);
-    static bool Initialize(int loadedCount, HANDLE hFile, /* OUT */ MethodContext** ppmc);
+    static bool Initialize(int mcIndex, unsigned char* buff, DWORD size, /* OUT */ MethodContext** ppmc);
+    static bool Initialize(int mcIndex, HANDLE hFile, /* OUT */ MethodContext** ppmc);
     ~MethodContext();
     void Destroy();
 

src/coreclr/ToolBox/superpmi/superpmi/superpmi.cpp

@@ -293,7 +293,8 @@ int __cdecl main(int argc, char* argv[])
         // Now read the data into a MethodContext. This could throw if the method context data is corrupt.
 
         loadedCount++;
-        if (!MethodContext::Initialize(loadedCount, mcb.buff, mcb.size, &mc))
+        const int mcIndex = reader->GetMethodContextIndex();
+        if (!MethodContext::Initialize(mcIndex, mcb.buff, mcb.size, &mc))
         {
             return (int)SpmiResult::GeneralFailure;
         }