JIT: Continue profile consistency checks until after finally cloning (d…

…otnet#109792)

Part of dotnet#107749. The next few opt phases alter flow substantially, such that we need to propagate new weight throughout the flowgraph. That will probably justify running profile synthesis after, in a later PR.

src/coreclr/jit/compiler.cpp

@@ -4609,11 +4609,6 @@ void Compiler::compCompile(void** methodCodePtr, uint32_t* methodCodeSize, JitFl
     // Record "start" values for post-inlining cycles and elapsed time.
     RecordStateAtEndOfInlining();
 
-    // Drop back to just checking profile likelihoods.
-    //
-    activePhaseChecks &= ~PhaseChecks::CHECK_PROFILE;
-    activePhaseChecks |= PhaseChecks::CHECK_LIKELIHOODS;
-
     if (opts.OptimizationEnabled())
     {
         // Build post-order and remove dead blocks
@@ -4658,6 +4653,11 @@ void Compiler::compCompile(void** methodCodePtr, uint32_t* methodCodeSize, JitFl
     //
     DoPhase(this, PHASE_CLONE_FINALLY, &Compiler::fgCloneFinally);
 
+    // Drop back to just checking profile likelihoods.
+    //
+    activePhaseChecks &= ~PhaseChecks::CHECK_PROFILE;
+    activePhaseChecks |= PhaseChecks::CHECK_LIKELIHOODS;
+
     // Do some flow-related optimizations
     //
     if (opts.OptimizationEnabled())

src/coreclr/jit/fgehopt.cpp

@@ -1038,8 +1038,27 @@ PhaseStatus Compiler::fgCloneFinally()
         const unsigned  finallyTryIndex = firstBlock->bbTryIndex;
         BasicBlock*     insertAfter     = nullptr;
         BlockToBlockMap blockMap(getAllocator());
-        unsigned        cloneBBCount   = 0;
-        weight_t const  originalWeight = firstBlock->hasProfileWeight() ? firstBlock->bbWeight : BB_ZERO_WEIGHT;
+        unsigned        cloneBBCount = 0;
+        weight_t        originalWeight;
+
+        // When distributing weight between the original and cloned regions,
+        // ensure only weight from region entries is considered.
+        // Flow from loop backedges within the region should not influence the weight distribution ratio.
+        if (firstBlock->hasProfileWeight())
+        {
+            originalWeight = firstBlock->bbWeight;
+            for (BasicBlock* const predBlock : firstBlock->PredBlocks())
+            {
+                if (!predBlock->KindIs(BBJ_CALLFINALLY))
+                {
+                    originalWeight = max(0.0, originalWeight - predBlock->bbWeight);
+                }
+            }
+        }
+        else
+        {
+            originalWeight = BB_ZERO_WEIGHT;
+        }
 
         for (BasicBlock* block = firstBlock; block != nextBlock; block = block->Next())
         {

src/coreclr/jit/flowgraph.cpp

@@ -1401,15 +1401,8 @@ void Compiler::fgAddSyncMethodEnterExit()
     // Create a block for the start of the try region, where the monitor enter call
     // will go.
     BasicBlock* const tryBegBB  = fgSplitBlockAtEnd(fgFirstBB);
-    BasicBlock* const tryNextBB = tryBegBB->Next();
     BasicBlock* const tryLastBB = fgLastBB;
 
-    // If we have profile data the new block will inherit the next block's weight
-    if (tryNextBB->hasProfileWeight())
-    {
-        tryBegBB->inheritWeight(tryNextBB);
-    }
-
     // Create a block for the fault.
     // It gets an artificial ref count.
 

src/coreclr/jit/objectalloc.cpp

@@ -673,6 +673,9 @@ unsigned int ObjectAllocator::MorphAllocObjNodeIntoStackAlloc(
         if (predBlock->hasProfileWeight())
         {
             block->setBBProfileWeight(predBlock->bbWeight);
+            JITDUMP("Profile weight into " FMT_BB " needs to be propagated to successors. Profile %s inconsistent.\n",
+                    block->bbNum, comp->fgPgoConsistent ? "is now" : "was already");
+            comp->fgPgoConsistent = false;
         }
 
         // Just lop off the JTRUE, the rest can clean up later