From fb9274a2dd65261d5358db353a95a2d2315f9ce0 Mon Sep 17 00:00:00 2001
From: Bruce Forstall <brucefo@microsoft.com>
Date: Mon, 17 Apr 2017 16:00:51 -0700
Subject: [PATCH] Hoist calls to NumSucc() out of loops

Should be a minor throughput improvement.


Commit migrated from https://github.com/dotnet/coreclr/commit/f503a568fd54d423510323921bb9065e398471e2
---
 src/coreclr/src/jit/importer.cpp | 15 ++++++++++-----
 src/coreclr/src/jit/lsra.cpp     |  3 ++-
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/coreclr/src/jit/importer.cpp b/src/coreclr/src/jit/importer.cpp
index 989130a..80fa143 100644
--- a/src/coreclr/src/jit/importer.cpp
+++ b/src/coreclr/src/jit/importer.cpp
@@ -15426,7 +15426,8 @@ inline void Compiler::impReimportMarkBlock(BasicBlock* block)
 
 void Compiler::impReimportMarkSuccessors(BasicBlock* block)
 {
-    for (unsigned i = 0; i < block->NumSucc(); i++)
+    const unsigned numSuccs = block->NumSucc();
+    for (unsigned i = 0; i < numSuccs; i++)
     {
         impReimportMarkBlock(block->GetSucc(i));
     }
@@ -15601,7 +15602,8 @@ void Compiler::impImportBlock(BasicBlock* block)
         JITDUMP("Marking BBF_INTERNAL block BB%02u as BBF_IMPORTED\n", block->bbNum);
         block->bbFlags |= BBF_IMPORTED;
 
-        for (unsigned i = 0; i < block->NumSucc(); i++)
+        const unsigned numSuccs = block->NumSucc();
+        for (unsigned i = 0; i < numSuccs; i++)
         {
             impImportBlockPending(block->GetSucc(i));
         }
@@ -16028,7 +16030,8 @@ SPILLSTACK:
         impReimportSpillClique(block);
 
         // For blocks that haven't been imported yet, we still need to mark them as pending import.
-        for (unsigned i = 0; i < block->NumSucc(); i++)
+        const unsigned numSuccs = block->NumSucc();
+        for (unsigned i = 0; i < numSuccs; i++)
         {
             BasicBlock* succ = block->GetSucc(i);
             if ((succ->bbFlags & BBF_IMPORTED) == 0)
@@ -16042,7 +16045,8 @@ SPILLSTACK:
         // otherwise just import the successors of block
 
         /* Does this block jump to any other blocks? */
-        for (unsigned i = 0; i < block->NumSucc(); i++)
+        const unsigned numSuccs = block->NumSucc();
+        for (unsigned i = 0; i < numSuccs; i++)
         {
             impImportBlockPending(block->GetSucc(i));
         }
@@ -16299,7 +16303,8 @@ void Compiler::impWalkSpillCliqueFromPred(BasicBlock* block, SpillCliqueWalker*
             BasicBlock* blk     = node->m_blk;
             FreeBlockListNode(node);
 
-            for (unsigned succNum = 0; succNum < blk->NumSucc(); succNum++)
+            const unsigned numSuccs = blk->NumSucc();
+            for (unsigned succNum = 0; succNum < numSuccs; succNum++)
             {
                 BasicBlock* succ = blk->GetSucc(succNum);
                 // If it's not already in the clique, add it, and also add it
diff --git a/src/coreclr/src/jit/lsra.cpp b/src/coreclr/src/jit/lsra.cpp
index e7c1c83..5576140 100644
--- a/src/coreclr/src/jit/lsra.cpp
+++ b/src/coreclr/src/jit/lsra.cpp
@@ -1378,7 +1378,8 @@ void LinearScan::setBlockSequence()
             assert(!"Switch with single successor");
         }
 
-        for (unsigned succIndex = 0; succIndex < block->NumSucc(compiler); succIndex++)
+        const unsigned numSuccs = block->NumSucc(compiler);
+        for (unsigned succIndex = 0; succIndex < numSuccs; succIndex++)
         {
             BasicBlock* succ = block->GetSucc(succIndex, compiler);
             if (checkForCriticalOutEdge && succ->GetUniquePred(compiler) == nullptr)
-- 
2.7.4