[PATCH] D44495: [CleanUp] Remove NumInstructions field from LoopVectorizer's RegisterUsage struct.

[Matt Davis via Phabricator via llvm-commits]

mattd created this revision.
mattd added reviewers: majnemer, congh.
Herald added a subscriber: rengolin.

This variable is largely going unused; aside from reporting number of instructions for in DEBUG builds.

The only use of NumInstructions is in debug output to represent the LoopSize.  That value can be can be misleading as it also includes metadata instructions (e.g., DBG_VALUE) which have no real impact.  If we do choose to keep this around, we probably should guard it by a DEBUG macro, as it's not used in production builds.


https://reviews.llvm.org/D44495

Files:
  lib/Transforms/Vectorize/LoopVectorize.cpp


Index: lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- lib/Transforms/Vectorize/LoopVectorize.cpp
+++ lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -1842,9 +1842,6 @@
 
     /// Holds the maximum number of concurrent live intervals in the loop.
     unsigned MaxLocalUsers;
-
-    /// Holds the number of instructions in the loop.
-    unsigned NumInstructions;
   };
 
   /// \return Returns information about the register usages of the loop for the
@@ -6307,7 +6304,6 @@
   // We divide by these constants so assume that we have at least one
   // instruction that uses at least one register.
   R.MaxLocalUsers = std::max(R.MaxLocalUsers, 1U);
-  R.NumInstructions = std::max(R.NumInstructions, 1U);
 
   // We calculate the interleave count using the following formula.
   // Subtract the number of loop invariants from the number of available
@@ -6434,7 +6430,6 @@
   DFS.perform(LI);
 
   RegisterUsage RU;
-  RU.NumInstructions = 0;
 
   // Each 'key' in the map opens a new interval. The values
   // of the map are the index of the 'last seen' usage of the
@@ -6453,7 +6448,6 @@
 
   unsigned Index = 0;
   for (BasicBlock *BB : make_range(DFS.beginRPO(), DFS.endRPO())) {
-    RU.NumInstructions += BB->size();
     for (Instruction &I : *BB) {
       IdxToInstr[Index++] = &I;
 
@@ -6563,7 +6557,6 @@
     DEBUG(dbgs() << "LV(REG): VF = " << VFs[i] << '\n');
     DEBUG(dbgs() << "LV(REG): Found max usage: " << MaxUsages[i] << '\n');
     DEBUG(dbgs() << "LV(REG): Found invariant usage: " << Invariant << '\n');
-    DEBUG(dbgs() << "LV(REG): LoopSize: " << RU.NumInstructions << '\n');
 
     RU.LoopInvariantRegs = Invariant;
     RU.MaxLocalUsers = MaxUsages[i];


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