Fix the stats collection for fast-isel. The failed count was only accounting

for a single miss and not all predecessor instructions that get selected by
the selection DAG instruction selector.  This is still not exact (e.g., over
states misses when folded/dead instructions are present), but it is a step in
the right direction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144832 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 18 insertions, 5 deletions

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 0afe990..8cecc17 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -892,13 +892,16 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
           FastIS->setLastLocalValue(0);
       }
 
+      unsigned NumFastIselRemaining = std::distance(Begin, End);
       // Do FastISel on as many instructions as possible.
       for (; BI != Begin; --BI) {
         const Instruction *Inst = llvm::prior(BI);
 
         // If we no longer require this instruction, skip it.
-        if (isFoldedOrDeadInstruction(Inst, FuncInfo))
+        if (isFoldedOrDeadInstruction(Inst, FuncInfo)) {
+          --NumFastIselRemaining;
           continue;
+        }
 
         // Bottom-up: reset the insert pos at the top, after any local-value
         // instructions.
@@ -906,6 +909,7 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
 
         // Try to select the instruction with FastISel.
         if (FastIS->SelectInstruction(Inst)) {
+          --NumFastIselRemaining;
           ++NumFastIselSuccess;
           // If fast isel succeeded, skip over all the folded instructions, and
           // then see if there is a load right before the selected instructions.
@@ -918,15 +922,18 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
           }
           if (BeforeInst != Inst && isa<LoadInst>(BeforeInst) &&
               BeforeInst->hasOneUse() &&
-              TryToFoldFastISelLoad(cast<LoadInst>(BeforeInst), Inst, FastIS))
+              TryToFoldFastISelLoad(cast<LoadInst>(BeforeInst), Inst, FastIS)) {
             // If we succeeded, don't re-select the load.
             BI = llvm::next(BasicBlock::const_iterator(BeforeInst));
+            --NumFastIselRemaining;
+            ++NumFastIselSuccess;
+          }
           continue;
         }
 
         // Then handle certain instructions as single-LLVM-Instruction blocks.
         if (isa<CallInst>(Inst)) {
-          ++NumFastIselFailures;
+
           if (EnableFastISelVerbose || EnableFastISelAbort) {
             dbgs() << "FastISel missed call: ";
             Inst->dump();
@@ -941,24 +948,30 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
           bool HadTailCall = false;
           SelectBasicBlock(Inst, BI, HadTailCall);
 
+          // Recompute NumFastIselRemaining as Selection DAG instruction
+          // selection may have handled the call, input args, etc.
+          unsigned RemainingNow = std::distance(Begin, BI);
+          NumFastIselFailures += NumFastIselRemaining - RemainingNow;
+
           // If the call was emitted as a tail call, we're done with the block.
           if (HadTailCall) {
             --BI;
             break;
           }
 
+          NumFastIselRemaining = RemainingNow;
           continue;
         }
 
         if (isa<TerminatorInst>(Inst) && !isa<BranchInst>(Inst)) {
           // Don't abort, and use a different message for terminator misses.
-          ++NumFastIselFailures;
+          NumFastIselFailures += NumFastIselRemaining;
           if (EnableFastISelVerbose || EnableFastISelAbort) {
             dbgs() << "FastISel missed terminator: ";
             Inst->dump();
           }
         } else {
-          ++NumFastIselFailures;
+          NumFastIselFailures += NumFastIselRemaining;
           if (EnableFastISelVerbose || EnableFastISelAbort) {
             dbgs() << "FastISel miss: ";
             Inst->dump();