JIT: defer creating throw helper blocks until simple lower

src/coreclr/jit/compiler.cpp

@@ -5038,6 +5038,10 @@ void Compiler::compCompile(void** methodCodePtr, uint32_t* methodCodeSize, JitFl
     // Insert GC Polls
     DoPhase(this, PHASE_INSERT_GC_POLLS, &Compiler::fgInsertGCPolls);
 
+    // Create any throw helper blocks that might be needed
+    //
+    DoPhase(this, PHASE_CREATE_THROW_HELPERS, &Compiler::fgCreateThrowHelperBlocks);
+
     if (opts.OptimizationEnabled())
     {
         // Optimize boolean conditions

src/coreclr/jit/compiler.h

@@ -6116,12 +6116,11 @@ class Compiler
     static unsigned acdHelper(SpecialCodeKind codeKind);
 
     AddCodeDsc* fgAddCodeList;
-    bool        fgAddCodeModf;
+    bool        fgRngChkThrowAdded;
     AddCodeDsc* fgExcptnTargetCache[SCK_COUNT];
 
-    BasicBlock* fgRngChkTarget(BasicBlock* block, SpecialCodeKind kind);
-
-    BasicBlock* fgAddCodeRef(BasicBlock* srcBlk, unsigned refData, SpecialCodeKind kind);
+    void fgAddCodeRef(BasicBlock* srcBlk, SpecialCodeKind kind);
+    PhaseStatus fgCreateThrowHelperBlocks();
 
 public:
     AddCodeDsc* fgFindExcptnTarget(SpecialCodeKind kind, unsigned refData);
@@ -6134,8 +6133,6 @@ class Compiler
     }
 
 private:
-    bool fgIsCodeAdded();
-
     bool fgIsThrowHlpBlk(BasicBlock* block);
 
 #if !FEATURE_FIXED_OUT_ARGS

src/coreclr/jit/compiler.hpp

@@ -3069,7 +3069,7 @@ inline Compiler::fgWalkResult Compiler::fgWalkTree(GenTree**    pTree,
 
 inline bool Compiler::fgIsThrowHlpBlk(BasicBlock* block)
 {
-    if (!fgIsCodeAdded())
+    if (!fgRngChkThrowAdded)
     {
         return false;
     }
@@ -3157,16 +3157,6 @@ inline unsigned Compiler::fgThrowHlpBlkStkLevel(BasicBlock* block)
 
 #endif // !FEATURE_FIXED_OUT_ARGS
 
-/*****************************************************************************
- *
- *  Return true if we've added any new basic blocks.
- */
-
-inline bool Compiler::fgIsCodeAdded()
-{
-    return fgAddCodeModf;
-}
-
 /*****************************************************************************
   Is the offset too big?
 */

src/coreclr/jit/compphases.h

@@ -99,6 +99,7 @@ CompPhaseNameMacro(PHASE_EXPAND_RTLOOKUPS,           "Expand runtime lookups",
 CompPhaseNameMacro(PHASE_EXPAND_STATIC_INIT,         "Expand static init",             false, -1, true)
 CompPhaseNameMacro(PHASE_EXPAND_TLS,                 "Expand TLS access",              false, -1, true)
 CompPhaseNameMacro(PHASE_INSERT_GC_POLLS,            "Insert GC Polls",                false, -1, true)
+CompPhaseNameMacro(PHASE_CREATE_THROW_HELPERS,       "Create throw helper blocks",     false, -1, true)
 CompPhaseNameMacro(PHASE_DETERMINE_FIRST_COLD_BLOCK, "Determine first cold block",     false, -1, true)
 CompPhaseNameMacro(PHASE_RATIONALIZE,                "Rationalize IR",                 false, -1, false)
 CompPhaseNameMacro(PHASE_SIMPLE_LOWERING,            "Do 'simple' lowering",           false, -1, false)

src/coreclr/jit/fgbasic.cpp

@@ -96,7 +96,6 @@ void Compiler::fgInit()
     // as the code that raises an exception when an array range check fails.
 
     fgAddCodeList = nullptr;
-    fgAddCodeModf = false;
 
     for (int i = 0; i < SCK_COUNT; i++)
     {
@@ -109,6 +108,9 @@ void Compiler::fgInit()
     /* This global flag is set whenever we remove a statement */
     fgStmtRemoved = false;
 
+    // This global flag is set when we create throw helper blocks
+    fgRngChkThrowAdded = false;
+
     /* Keep track of whether or not EH statements have been optimized */
     fgOptimizedFinally = false;