JIT: Avoid byref strength reductions in loops with suspension points (#115605)

Reducing to a byref type (e.g. when iterating through an array) in a
loop with suspension points is not valid, since the new byref IV will be
live across the suspension point. In those cases instead strength reduce
to the index.

Author: jakobbotsch

src/coreclr/jit/compiler.h

@@ -72,22 +72,22 @@ inline var_types genActualType(T value);
  *                  Forward declarations
  */
 
-struct InfoHdr;             // defined in GCInfo.h
-struct escapeMapping_t;     // defined in fgdiagnostic.cpp
-class emitter;              // defined in emit.h
-struct ShadowParamVarInfo;  // defined in GSChecks.cpp
-struct InitVarDscInfo;      // defined in registerargconvention.h
-class FgStack;              // defined in fgbasic.cpp
-class Instrumentor;         // defined in fgprofile.cpp
-class SpanningTreeVisitor;  // defined in fgprofile.cpp
-class CSE_DataFlow;         // defined in optcse.cpp
-struct CSEdsc;              // defined in optcse.h
-class CSE_HeuristicCommon;  // defined in optcse.h
-class OptBoolsDsc;          // defined in optimizer.cpp
-struct JumpThreadInfo;      // defined in redundantbranchopts.cpp
-class ProfileSynthesis;     // defined in profilesynthesis.h
-class LoopLocalOccurrences; // defined in inductionvariableopts.cpp
-class RangeCheck;           // defined in rangecheck.h
+struct InfoHdr;            // defined in GCInfo.h
+struct escapeMapping_t;    // defined in fgdiagnostic.cpp
+class emitter;             // defined in emit.h
+struct ShadowParamVarInfo; // defined in GSChecks.cpp
+struct InitVarDscInfo;     // defined in registerargconvention.h
+class FgStack;             // defined in fgbasic.cpp
+class Instrumentor;        // defined in fgprofile.cpp
+class SpanningTreeVisitor; // defined in fgprofile.cpp
+class CSE_DataFlow;        // defined in optcse.cpp
+struct CSEdsc;             // defined in optcse.h
+class CSE_HeuristicCommon; // defined in optcse.h
+class OptBoolsDsc;         // defined in optimizer.cpp
+struct JumpThreadInfo;     // defined in redundantbranchopts.cpp
+class ProfileSynthesis;    // defined in profilesynthesis.h
+class PerLoopInfo;         // defined in inductionvariableopts.cpp
+class RangeCheck;          // defined in rangecheck.h
 #ifdef DEBUG
 struct IndentStack;
 #endif
@@ -7654,33 +7654,30 @@ class Compiler
     void optVisitBoundingExitingCondBlocks(FlowGraphNaturalLoop* loop, TFunctor func);
     bool optMakeLoopDownwardsCounted(ScalarEvolutionContext& scevContext,
                                      FlowGraphNaturalLoop*   loop,
-                                     LoopLocalOccurrences*   loopLocals);
+                                     PerLoopInfo*            loopLocals);
     bool optMakeExitTestDownwardsCounted(ScalarEvolutionContext& scevContext,
                                          FlowGraphNaturalLoop*   loop,
                                          BasicBlock*             exiting,
-                                         LoopLocalOccurrences*   loopLocals);
+                                         PerLoopInfo*            loopLocals);
     bool optCanAndShouldChangeExitTest(GenTree* cond, bool dump);
-    bool optLocalHasNonLoopUses(unsigned lclNum, FlowGraphNaturalLoop* loop, LoopLocalOccurrences* loopLocals);
+    bool optLocalHasNonLoopUses(unsigned lclNum, FlowGraphNaturalLoop* loop, PerLoopInfo* loopLocals);
     bool optLocalIsLiveIntoBlock(unsigned lclNum, BasicBlock* block);
 
-    bool optWidenIVs(ScalarEvolutionContext& scevContext, FlowGraphNaturalLoop* loop, LoopLocalOccurrences* loopLocals);
-    bool optWidenPrimaryIV(FlowGraphNaturalLoop* loop,
-                           unsigned              lclNum,
-                           ScevAddRec*           addRec,
-                           LoopLocalOccurrences* loopLocals);
+    bool optWidenIVs(ScalarEvolutionContext& scevContext, FlowGraphNaturalLoop* loop, PerLoopInfo* loopLocals);
+    bool optWidenPrimaryIV(FlowGraphNaturalLoop* loop, unsigned lclNum, ScevAddRec* addRec, PerLoopInfo* loopLocals);
 
     bool optCanSinkWidenedIV(unsigned lclNum, FlowGraphNaturalLoop* loop);
     bool optIsIVWideningProfitable(unsigned              lclNum,
                                    BasicBlock*           initBlock,
                                    bool                  initedToConstant,
                                    FlowGraphNaturalLoop* loop,
-                                   LoopLocalOccurrences* loopLocals);
+                                   PerLoopInfo*          loopLocals);
     void optBestEffortReplaceNarrowIVUses(
         unsigned lclNum, unsigned ssaNum, unsigned newLclNum, BasicBlock* block, Statement* firstStmt);
     void optReplaceWidenedIV(unsigned lclNum, unsigned ssaNum, unsigned newLclNum, Statement* stmt);
     void optSinkWidenedIV(unsigned lclNum, unsigned newLclNum, FlowGraphNaturalLoop* loop);
 
-    bool optRemoveUnusedIVs(FlowGraphNaturalLoop* loop, LoopLocalOccurrences* loopLocals);
+    bool optRemoveUnusedIVs(FlowGraphNaturalLoop* loop, PerLoopInfo* loopLocals);
     bool optIsUpdateOfIVWithoutSideEffects(GenTree* tree, unsigned lclNum);
 
     // Redundant branch opts