Allow retrieval of sourceInstruction from TraceUltimateMoveSource

include/base/SMPInstr.h

@@ -1069,7 +1069,8 @@ public:
 
 	// Trace UseOp through register moves back to its stack location or immediate value source.
 	//  Return true if we are passing an immediate or stack location back in UltSource.
-	bool TraceUltimateMoveSource(const STARSOpndTypePtr &UseOp, int UseSSANum, STARSOpndTypePtr &UltSource, bool &FPRelative);
+    bool TraceUltimateMoveSource(const STARSOpndTypePtr &UseOp, int UseSSANum, STARSOpndTypePtr &UltSource, bool &FPRelative);
+    bool TraceUltimateMoveSource(const STARSOpndTypePtr &UseOp, int UseSSANum, STARSOpndTypePtr &UltSource, bool &FPRelative, SMPInstr* &SourceInstr);
 	bool HasNoCodeXrefs(void); // inst has no code xrefs
 	bool IsLoopExitStatement(bool &InvertedExit); // true => jump is used to exit a loop
 	inline bool AnalyzeSwitchInfo(struct SwitchTableInfo &TableInfo) { return STARSInstPtr->AnalyzeSwitchStatement(this, TableInfo); };

src/base/SMPInstr.cpp

@@ -14002,6 +14002,14 @@ void SMPInstr::SCCPFetchConstDefValue(const STARSOpndTypePtr &DefOp, STARS_SCCP_
 // Trace UseOp through register moves back to its stack location or immediate value source.
 //  Return true if we are passing an immediate or stack location back in UltSource.
 bool SMPInstr::TraceUltimateMoveSource(const STARSOpndTypePtr &UseOp, int UseSSANum, STARSOpndTypePtr &UltSource, bool &FPRelative) {
+    SMPInstr *discard = nullptr;
+    return this->TraceUltimateMoveSource(UseOp, UseSSANum, UltSource, FPRelative, discard);
+}
+
+// Trace UseOp through register moves back to its stack location or immediate value source.
+//  Return true if we are passing an immediate or stack location back in UltSource.
+// SourceInstr will contain the source instruction if we were able to find it. If not, it is set to nullptr
+bool SMPInstr::TraceUltimateMoveSource(const STARSOpndTypePtr &UseOp, int UseSSANum, STARSOpndTypePtr &UltSource, bool &FPRelative, SMPInstr* &SourceInstr) {
 	// If we hit an immediate value or a stack location, we are done.
 	bool UseFP = this->GetBlock()->GetFunc()->UsesFramePointer();
 	STARSOpndTypePtr DefOp = nullptr, ImmOp = nullptr;
@@ -14011,18 +14019,21 @@ bool SMPInstr::TraceUltimateMoveSource(const STARSOpndTypePtr &UseOp, int UseSSA
 	STARS_ea_t DefAddr;
 	SMPInstr *DefInst;
+    SourceInstr = nullptr;
 	UltSource = nullptr;
 	bool StackOp = MDIsDirectStackAccessOpnd(UseOp, UseFP);
 	bool RegisterOp = (UseOp->IsRegOp());
 	if (this->GetOptType() == 3) { // move instruction
 		if (UseOp->IsImmedOp()) {
+            SourceInstr = this;
 			UltSource = UseOp;
 			return true;
 		}
 		else if ((!RegisterOp) && (!StackOp)) {
 			// We only trace the move chain through registers or stack locations to an ultimate 
 			//  load-effective-address of a stack location, or a move of an immediate value.
+            SourceInstr = this;
 			return false;
 		}
 	} 
@@ -14074,6 +14085,7 @@ bool SMPInstr::TraceUltimateMoveSource(const STARSOpndTypePtr &UseOp, int UseSSA
 	}
 	else if (DefInst->MDIsLoadEffectiveAddressInstr()) {
 		NewUseOp = DefInst->GetLeaMemUseOp();
+        SourceInstr = DefInst;
 		if (MDIsDirectStackAccessOpnd(NewUseOp, UseFP)) {
 			UltSource = NewUseOp;
 			FPRelative = DefInst->HasFPNormalizedToSP();
@@ -14089,6 +14101,7 @@ bool SMPInstr::TraceUltimateMoveSource(const STARSOpndTypePtr &UseOp, int UseSSA
 	// Case 1: A register is cleared. Same as assigning immediate value zero to the reg.
 	else if (DefInst->IsRegClearIdiom()) {
 		UltSource = this->STARSInstPtr->MakeImmediateOpnd(0);
+        SourceInstr = DefInst;
 		// why would we memset a zero byte region?
 		return true;
 	}
@@ -14107,6 +14120,7 @@ bool SMPInstr::TraceUltimateMoveSource(const STARSOpndTypePtr &UseOp, int UseSSA
 		NewDefInst = DefInst->GetBlock()->GetFunc()->GetInstFromAddr(DefAddr);
 		if (NewDefInst->MDIsLoadEffectiveAddressInstr()) {
 			NewUseOp = NewDefInst->GetLeaMemUseOp()->clone();
+            SourceInstr = NewDefInst;
 			if (MDIsDirectStackAccessOpnd(NewUseOp, UseFP)) {
 				// We have the code sequence we were searching for when we first saw the
 				//  addition of an immediate value to a register, e.g.: