JIT: Enable compaction of all BBJ_ALWAYS blocks

src/coreclr/jit/block.h

@@ -468,7 +468,7 @@ enum BasicBlockFlags : uint64_t
     // Flags to update when two blocks are compacted
 
     BBF_COMPACT_UPD = BBF_GC_SAFE_POINT | BBF_NEEDS_GCPOLL | BBF_HAS_JMP | BBF_HAS_IDX_LEN | BBF_HAS_MD_IDX_LEN | BBF_BACKWARD_JUMP | \
-                      BBF_HAS_NEWOBJ | BBF_HAS_NULLCHECK | BBF_HAS_MDARRAYREF,
+                      BBF_HAS_NEWOBJ | BBF_HAS_NULLCHECK | BBF_HAS_MDARRAYREF | BBF_LOOP_HEAD,
 
     // Flags a block should not have had before it is split.
 

src/coreclr/jit/compiler.h

@@ -6086,9 +6086,9 @@ class Compiler
 
     void fgPrepareCallFinallyRetForRemoval(BasicBlock* block);
 
-    bool fgCanCompactBlocks(BasicBlock* block, BasicBlock* bNext);
+    bool fgCanCompactBlock(BasicBlock* block);
 
-    void fgCompactBlocks(BasicBlock* block, BasicBlock* bNext DEBUGARG(bool doDebugCheck = true));
+    void fgCompactBlock(BasicBlock* block);
 
     BasicBlock* fgConnectFallThrough(BasicBlock* bSrc, BasicBlock* bDst);
 
@@ -6157,7 +6157,7 @@ class Compiler
 
     bool fgIsForwardBranch(BasicBlock* bJump, BasicBlock* bDest, BasicBlock* bSrc = nullptr);
 
-    bool fgUpdateFlowGraph(bool doTailDup = false, bool isPhase = false);
+    bool fgUpdateFlowGraph(bool doTailDup = false, bool isPhase = false, bool doAggressiveCompaction = true);
     PhaseStatus fgUpdateFlowGraphPhase();
 
     PhaseStatus fgDfsBlocksAndRemove();

src/coreclr/jit/fgdiagnostic.cpp

@@ -139,7 +139,7 @@ void Compiler::fgDebugCheckUpdate()
 
         /* no un-compacted blocks */
 
-        if (fgCanCompactBlocks(block, block->Next()))
+        if (fgCanCompactBlock(block))
         {
             noway_assert(!"Found un-compacted blocks!");
         }