JIT: Remove implicit fallthrough assumption in `fgExpandRarelyRunBloc…

…ks` (dotnet#107350)
Coderrob · Sep 5, 2024 · 0961328 · 0961328
1 parent 40cafd7
commit 0961328
Showing 1 changed file with 4 additions and 12 deletions.
diff --git a/src/coreclr/jit/fgopt.cpp b/src/coreclr/jit/fgopt.cpp
@@ -3126,7 +3126,7 @@ bool Compiler::fgExpandRarelyRunBlocks()
                 break;
 
             case BBJ_COND:
-                if (block->isRunRarely() && bPrev->GetTrueTarget()->isRunRarely())
+                if (bPrev->GetTrueTarget()->isRunRarely() && bPrev->GetFalseTarget()->isRunRarely())
                 {
                     INDEBUG(reason = "Both sides of a conditional jump are rarely run");
                     setRarelyRun = true;
@@ -3230,21 +3230,13 @@ bool Compiler::fgExpandRarelyRunBlocks()
             }
         }
 
-        /* COMPACT blocks if possible */
-        if (fgCanCompactBlock(bPrev))
-        {
-            fgCompactBlock(bPrev);
-
-            block = bPrev;
-            continue;
-        }
         //
         // if bPrev->bbWeight is not based upon profile data we can adjust
         // the weights of bPrev and block
         //
-        else if (bPrev->isBBCallFinallyPair() &&         // we must have a BBJ_CALLFINALLY and BBJ_CALLFINALLYRET pair
-                 (bPrev->bbWeight != block->bbWeight) && // the weights are currently different
-                 !bPrev->hasProfileWeight())             // and the BBJ_CALLFINALLY block is not using profiled weights
+        if (bPrev->isBBCallFinallyPair() &&         // we must have a BBJ_CALLFINALLY and BBJ_CALLFINALLYRET pair
+            (bPrev->bbWeight != block->bbWeight) && // the weights are currently different
+            !bPrev->hasProfileWeight())             // and the BBJ_CALLFINALLY block is not using profiled weights
         {
             if (block->isRunRarely())
             {