[Linux-arm] Do not add resolution move in BBCallAlwaysPairTail (#48828)

* [Linux-arm] Do not add resolution move in BBCallAlwaysPairTail Sample failures: https://helixre8s23ayyeko0k025g8.blob.core.windows.net/dotnet-runtime-refs-pull-47307-head-79786b731dd04634a8/PayloadGroup0/console.9e154ef8.log?sv=2019-07-07&se=2021-03-03T09%3A49%3A11Z&sr=c&sp=rl&sig=rHImoZWkkCsi35nI3DzfxPkbCPTbiOg2B8uspiWOIVE%3D https://helixre8s23ayyeko0k025g8.blob.core.windows.net/dotnet-runtime-refs-pull-47307-head-79786b731dd04634a8/PayloadGroup0/console.9e154ef8.log?sv=2019-07-07&se=2021-03-03T09%3A49%3A11Z&sr=c&sp=rl&sig=rHImoZWkkCsi35nI3DzfxPkbCPTbiOg2B8uspiWOIVE%3D * review comments * jit format
dotnet · Mar 2, 2021 · e0b8c2e · e0b8c2e
1 parent 22d375c
commit e0b8c2e
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Showing 2 changed files with 17 additions and 10 deletions.
diff --git a/src/coreclr/jit/block.cpp b/src/coreclr/jit/block.cpp
@@ -1554,7 +1554,7 @@ bool BasicBlock::isBBCallAlwaysPair()
 }
 
 //------------------------------------------------------------------------
-// isBBCallAlwaysPairTail: Determine if this is the last block of a BBJ_CALLFINALLY/BBJ_ALWAYS pari
+// isBBCallAlwaysPairTail: Determine if this is the last block of a BBJ_CALLFINALLY/BBJ_ALWAYS pair
 //
 // Return Value:
 //    True iff "this" is the last block of a BBJ_CALLFINALLY/BBJ_ALWAYS pair

diff --git a/src/coreclr/jit/lsra.cpp b/src/coreclr/jit/lsra.cpp
@@ -849,6 +849,14 @@ void LinearScan::setBlockSequence()
         blockInfo[block->bbNum].splitEdgeCount     = 0;
 #endif // TRACK_LSRA_STATS
 
+        // We treat BBCallAlwaysPairTail blocks as having EH flow, since we can't
+        // insert resolution moves into those blocks.
+        if (block->isBBCallAlwaysPairTail())
+        {
+            blockInfo[block->bbNum].hasEHBoundaryIn  = true;
+            blockInfo[block->bbNum].hasEHBoundaryOut = true;
+        }
+
         bool hasUniquePred = (block->GetUniquePred(compiler) != nullptr);
         for (flowList* pred = block->bbPreds; pred != nullptr; pred = pred->flNext)
         {
@@ -866,15 +874,11 @@ void LinearScan::setBlockSequence()
                 }
             }
 
-            // We treat BBCallAlwaysPairTail blocks as having EH flow, since we can't
-            // insert resolution moves into those blocks.
-            if (block->isBBCallAlwaysPairTail())
-            {
-                blockInfo[block->bbNum].hasEHBoundaryIn  = true;
-                blockInfo[block->bbNum].hasEHBoundaryOut = true;
-            }
-            else if (predBlock->hasEHBoundaryOut() || predBlock->isBBCallAlwaysPairTail())
+            if (!block->isBBCallAlwaysPairTail() &&
+                (predBlock->hasEHBoundaryOut() || predBlock->isBBCallAlwaysPairTail()))
             {
+                assert(!block->isBBCallAlwaysPairTail());
+
                 if (hasUniquePred)
                 {
                     // A unique pred with an EH out edge won't allow us to keep any variables enregistered.
@@ -8210,6 +8214,10 @@ void LinearScan::addResolution(
                !blockInfo[block->bbNum].hasEHBoundaryIn);
         insertionPointString = "top";
     }
+
+    // We should never add resolution move inside BBCallAlwaysPairTail.
+    noway_assert(!block->isBBCallAlwaysPairTail());
+
 #endif // DEBUG
 
     JITDUMP("   " FMT_BB " %s: move V%02u from ", block->bbNum, insertionPointString, interval->varNum);
@@ -8582,7 +8590,6 @@ void LinearScan::resolveEdges()
         }
 
         unsigned    succCount       = block->NumSucc(compiler);
-        flowList*   preds           = block->bbPreds;
         BasicBlock* uniquePredBlock = block->GetUniquePred(compiler);
 
         // First, if this block has a single predecessor,