Never set fgPgoSingleEdge for cctors or large single-edge blocks

src/coreclr/jit/fgprofilesynthesis.cpp

@@ -250,14 +250,53 @@ void ProfileSynthesis::Run(ProfileSynthesisOption option)
     m_comp->fgPgoConsistent  = !m_approximate;
 
     // A simple check whether the current method has more than one edge.
-    m_comp->fgPgoSingleEdge = true;
-    for (BasicBlock* const block : m_comp->Blocks())
+    // Ignore static constructors - they're never expected to be called more than once.
+    const bool preferSize = m_comp->opts.jitFlags->IsSet(JitFlags::JIT_FLAG_SIZE_OPT);
+    const bool isCctor    = ((m_comp->info.compFlags & FLG_CCTOR) == FLG_CCTOR);
+    m_comp->fgPgoSingleEdge = !isCctor && !preferSize;
+
+    if (m_comp->fgPgoSingleEdge)
     {
-        if (block->NumSucc() > 1)
+        for (BasicBlock* const block : m_comp->Blocks())
         {
-            m_comp->fgPgoSingleEdge = false;
-            break;
+            if (block->NumSucc() > 1)
+            {
+                m_comp->fgPgoSingleEdge = false;
+                break;
+            }
+        }
+    }
+
+    // fgPgoSingleEdge targets mostly small wrapper-like methods, so we ignore single-edge code
+    // with a lot of calls.
+    int callsCount = 0;
+    const int MaxCallsForSingleEdgeBlocks = 10;
+    if (m_comp->fgPgoSingleEdge)
+    {
+        // Loop all BBs again because the previous block-only loop was more likely to
+        // bail out early.
+        for (BasicBlock* const block : m_comp->Blocks())
+        {
+            for (Statement* const stmt : block->Statements())
+            {
+                if ((stmt->GetRootNode() != nullptr) && ((stmt->GetRootNode()->gtFlags & GTF_CALL) != 0))
+                {
+                    for (GenTree* const tree : stmt->TreeList())
+                    {
+                        if (tree->IsCall())
+                        {
+                            callsCount++;
+                            if (callsCount > MaxCallsForSingleEdgeBlocks)
+                            {
+                                m_comp->fgPgoSingleEdge = false;
+                                goto TOO_MANY_CALLS;
+                            }
+                        }
+                    }
+                }
+            }
         }
+    TOO_MANY_CALLS:
     }
 
     m_comp->Metrics.ProfileSynthesizedBlendedOrRepaired++;

src/coreclr/jit/jit.h

@@ -738,14 +738,7 @@ inline size_t unsigned_abs(int64_t x)
 #define FEATURE_TAILCALL_OPT_SHARED_RETURN 0
 #endif // !FEATURE_TAILCALL_OPT
 
-#define CLFLG_CODESIZE   0x00001
-#define CLFLG_CODESPEED  0x00002
-#define CLFLG_CSE        0x00004
 #define CLFLG_REGVAR     0x00008
-#define CLFLG_RNGCHKOPT  0x00010
-#define CLFLG_DEADSTORE  0x00020
-#define CLFLG_CODEMOTION 0x00040
-#define CLFLG_QMARK      0x00080
 #define CLFLG_TREETRANS  0x00100
 #define CLFLG_INLINING   0x00200
 
@@ -761,10 +754,7 @@ inline size_t unsigned_abs(int64_t x)
 #define FEATURE_LOOP_ALIGN 0
 #endif
 
-#define CLFLG_MAXOPT                                                                                                   \
-    (CLFLG_CSE | CLFLG_REGVAR | CLFLG_RNGCHKOPT | CLFLG_DEADSTORE | CLFLG_CODEMOTION | CLFLG_QMARK | CLFLG_TREETRANS | \
-     CLFLG_INLINING | CLFLG_STRUCTPROMOTE)
-
+#define CLFLG_MAXOPT (CLFLG_REGVAR | CLFLG_TREETRANS | CLFLG_INLINING | CLFLG_STRUCTPROMOTE)
 #define CLFLG_MINOPT (CLFLG_TREETRANS)
 
 /*****************************************************************************/