Fix merge issue

Modify weight for EH vars in LIR Take into account how many callee save regs there are
dotnet · Nov 20, 2019 · f96f1cf · f96f1cf
1 parent c2ae4dd
commit f96f1cf
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Showing 4 changed files with 41 additions and 17 deletions.
diff --git a/src/jit/compiler.cpp b/src/jit/compiler.cpp
@@ -6170,8 +6170,9 @@ int Compiler::compCompileHelper(CORINFO_MODULE_HANDLE            classPtr,
 #ifdef DEBUG
     if (JitConfig.DumpJittedMethods() == 1 && !compIsForInlining())
     {
-        printf("Compiling %4d %s::%s, IL size = %u, hash=%08x %s\n", Compiler::jitTotalMethodCompiled, info.compClassName,
-               info.compMethodName, info.compILCodeSize, info.compMethodHash(), compGetTieringName());
+        printf("Compiling %4d %s::%s, IL size = %u, hash=%08x %s\n", Compiler::jitTotalMethodCompiled,
+               info.compClassName, info.compMethodName, info.compILCodeSize, info.compMethodHash(),
+               compGetTieringName());
     }
     if (compIsForInlining())
     {

diff --git a/src/jit/lclvars.cpp b/src/jit/lclvars.cpp
@@ -4113,8 +4113,20 @@ void Compiler::lvaComputeRefCounts(bool isRecompute, bool setSlotNumbers)
                     case GT_STORE_LCL_VAR:
                     case GT_STORE_LCL_FLD:
                     {
-                        const unsigned lclNum = node->AsLclVarCommon()->GetLclNum();
-                        lvaTable[lclNum].incRefCnts(weight, this);
+                        LclVarDsc* varDsc = lvaGetDesc(node->AsLclVarCommon());
+                        // If this is an EH var, use a zero weight for defs, so that we don't
+                        // count those in our heuristic for register allocation, since they always
+                        // must be stored, so there's no value in enregistering them at defs; only
+                        // if there are enough uses to justify it.
+                        if (varDsc->lvLiveInOutOfHndlr && !varDsc->lvDoNotEnregister &&
+                            ((node->gtFlags & GTF_VAR_DEF) != 0))
+                        {
+                            varDsc->incRefCnts(0, this);
+                        }
+                        else
+                        {
+                            varDsc->incRefCnts(weight, this);
+                        }
                         break;
                     }
 

diff --git a/src/jit/lsra.cpp b/src/jit/lsra.cpp
@@ -186,7 +186,16 @@ unsigned LinearScan::getWeight(RefPosition* refPos)
             if (refPos->getInterval()->isSpilled)
             {
                 // Decrease the weight if the interval has already been spilled.
-                weight -= BB_UNITY_WEIGHT;
+                if (varDsc->lvLiveInOutOfHndlr)
+                {
+                    // An EH var is always spilled at defs, and we'll decrease the weight by half,
+                    // since only the reload is needed.
+                    weight = weight / 2;
+                }
+                else
+                {
+                    weight -= compiler->fgFirstBB->getBBWeight(compiler);
+                }
             }
         }
         else
@@ -4798,17 +4807,17 @@ void LinearScan::processBlockStartLocations(BasicBlock* currentBlock)
 #if DEBUG
         if (blockInfo[currentBlock->bbNum].hasEHBoundaryIn)
         {
-#if DEBUG
-        // This should still be in its initialized empty state.
-        for (unsigned varIndex = 0; varIndex < compiler->lvaTrackedCount; varIndex++)
-        {
-            // In the case where we're extending lifetimes for stress, we are intentionally modeling variables
-            // as live when they really aren't to create extra register pressure & constraints.
-            // However, this means that non-EH-vars will be live into EH regions. We can and should ignore the
-            // locations of these. Note that they aren't reported to codegen anyway.
-            if (!getLsraExtendLifeTimes() || VarSetOps::IsMember(compiler, currentBlock->bbLiveIn, varIndex))
+            // This should still be in its initialized empty state.
+            for (unsigned varIndex = 0; varIndex < compiler->lvaTrackedCount; varIndex++)
             {
-                assert(inVarToRegMap[varIndex] == REG_STK);
+                // In the case where we're extending lifetimes for stress, we are intentionally modeling variables
+                // as live when they really aren't to create extra register pressure & constraints.
+                // However, this means that non-EH-vars will be live into EH regions. We can and should ignore the
+                // locations of these. Note that they aren't reported to codegen anyway.
+                if (!getLsraExtendLifeTimes() || VarSetOps::IsMember(compiler, currentBlock->bbLiveIn, varIndex))
+                {
+                    assert(inVarToRegMap[varIndex] == REG_STK);
+                }
             }
         }
 #endif // DEBUG
@@ -8236,7 +8245,7 @@ void LinearScan::handleOutgoingCriticalEdges(BasicBlock* block)
                 // so if we have only EH vars, we'll do that instead of splitting the edge.
                 if ((compiler->compHndBBtabCount > 0) && VarSetOps::IsSubset(compiler, edgeResolutionSet, exceptVars))
                 {
-                    GenTree* insertionPoint = LIR::AsRange(succBlock).FirstNonPhiNode();
+                    GenTree*        insertionPoint = LIR::AsRange(succBlock).FirstNonPhiNode();
                     VarSetOps::Iter edgeSetIter(compiler, edgeResolutionSet);
                     unsigned        edgeVarIndex = 0;
                     while (edgeSetIter.NextElem(&edgeVarIndex))

diff --git a/src/jit/lsrabuild.cpp b/src/jit/lsrabuild.cpp
@@ -2399,7 +2399,9 @@ void LinearScan::buildIntervals()
                     // Given that we also don't have a good way to tell whether the variable is live
                     // across a call in the non-EH code, we'll be extra conservative about this.
                     // Note that for writeThru intervals we don't update the preferences to be only callee-save.
-                    if (weight <= (BB_UNITY_WEIGHT * 7))
+                    unsigned calleeSaveCount =
+                        (varTypeIsFloating(interval->registerType)) ? CNT_CALLEE_SAVED_FLOAT : CNT_CALLEE_ENREG;
+                    if ((weight <= (BB_UNITY_WEIGHT * 7)) || varDsc->lvVarIndex >= calleeSaveCount)
                     {
                         // If this is relatively low weight, don't prefer callee-save at all.
                         interval->preferCalleeSave = false;