Quick look-up for block in loop.

This patch implements quick look-up for block in loop by maintaining a hash set for blocks.
It improves the efficiency of loop analysis a lot, the biggest improvement could be 5-6%(458.sjeng).
Below are the compilation time for our benchmark in llc before & after the patch.

Benchmark	llc - trunk		llc - patched	
401.bzip2	0.339081	100.00%	0.329657	102.86%
403.gcc		19.853966	100.00%	19.605466	101.27%
429.mcf		0.049823	100.00%	0.048451	102.83%
433.milc	0.514898	100.00%	0.510217	100.92%
444.namd	1.109328	100.00%	1.103481	100.53%
445.gobmk	4.988028	100.00%	4.929114	101.20%
456.hmmer	0.843871	100.00%	0.825865	102.18%
458.sjeng	0.754238	100.00%	0.714095	105.62%
464.h264ref	2.9668		100.00%	2.90612		102.09%
471.omnetpp	4.556533	100.00%	4.511886	100.99%
bitmnp01	0.038168	100.00%	0.0357		106.91%
idctrn01	0.037745	100.00%	0.037332	101.11%
libquake2	3.78689		100.00%	3.76209		100.66%
libquake_	2.251525	100.00%	2.234104	100.78%
linpack		0.033159	100.00%	0.032788	101.13%
matrix01	0.045319	100.00%	0.043497	104.19%
nbench		0.333161	100.00%	0.329799	101.02%
tblook01	0.017863	100.00%	0.017666	101.12%
ttsprk01	0.054337	100.00%	0.053057	102.41%

Reviewer	: Andrew Trick <atrick@apple.com>, Hal Finkel <hfinkel@anl.gov>
Approver	: Andrew Trick <atrick@apple.com>
Test		: Pass make check-all & llvm test-suite


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193460 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 2 insertions, 13 deletions

diff --git a/lib/Transforms/Utils/LCSSA.cpp b/lib/Transforms/Utils/LCSSA.cpp
index 2d1b166c21..f15e8d5927 100644
--- a/lib/Transforms/Utils/LCSSA.cpp
+++ b/lib/Transforms/Utils/LCSSA.cpp
@@ -55,7 +55,6 @@ namespace {
     DominatorTree *DT;
     LoopInfo *LI;
     ScalarEvolution *SE;
-    std::vector<BasicBlock*> LoopBlocks;
     PredIteratorCache PredCache;
     Loop *L;
     
@@ -82,11 +81,6 @@ namespace {
       // Check the special guarantees that LCSSA makes.
       assert(L->isLCSSAForm(*DT) && "LCSSA form not preserved!");
     }
-
-    /// inLoop - returns true if the given block is within the current loop
-    bool inLoop(BasicBlock *B) const {
-      return std::binary_search(LoopBlocks.begin(), LoopBlocks.end(), B);
-    }
   };
 }
   
@@ -129,11 +123,6 @@ bool LCSSA::runOnLoop(Loop *TheLoop, LPPassManager &LPM) {
   if (ExitBlocks.empty())
     return false;
   
-  // Speed up queries by creating a sorted vector of blocks.
-  LoopBlocks.clear();
-  LoopBlocks.insert(LoopBlocks.end(), L->block_begin(), L->block_end());
-  array_pod_sort(LoopBlocks.begin(), LoopBlocks.end());
-  
   // Look at all the instructions in the loop, checking to see if they have uses
   // outside the loop.  If so, rewrite those uses.
   bool MadeChange = false;
@@ -198,7 +187,7 @@ bool LCSSA::ProcessInstruction(Instruction *Inst,
     if (PHINode *PN = dyn_cast<PHINode>(U))
       UserBB = PN->getIncomingBlock(UI);
     
-    if (InstBB != UserBB && !inLoop(UserBB))
+    if (InstBB != UserBB && !L->contains(UserBB))
       UsesToRewrite.push_back(&UI.getUse());
   }
 
@@ -244,7 +233,7 @@ bool LCSSA::ProcessInstruction(Instruction *Inst,
       // If the exit block has a predecessor not within the loop, arrange for
       // the incoming value use corresponding to that predecessor to be
       // rewritten in terms of a different LCSSA PHI.
-      if (!inLoop(*PI))
+      if (!L->contains(*PI))
         UsesToRewrite.push_back(
           &PN->getOperandUse(
             PN->getOperandNumForIncomingValue(PN->getNumIncomingValues()-1)));