Revert "Restrict the use of ConstantFolding's VisitIf"

This reverts commit 5eb1fd0dae3832ceee2102613bb08c291daca6f3.

Reason for revert: In aosp/2903248 we implemented a faster way of
doing `ReplaceUsesDominatedBy` which is used by `VisitIf`. The impact
of `VisitIf` is now small enough that running VisitIf in all passes
is faster that the previous implementation running some of the time.

This CLs re-enables the optimization in all constant folding passes
because:
A) Lets this optimization (and others that can use the result) kick in
   earlier
B) Run it for callee graphs in the inliner (which has been disabled as
   of CL aosp/2543831)
C) Consistency of the ConstantFolding pass, which helps to have a
   simpler mental model

Bug: 278626992
Test: art/test/testrunner/testrunner.py --host --64 --optimizing -b
Test: Locally compiled GMS and compared time to compile
Change-Id: I5dc5f591557c8de0bc4d23dbfd0b91b5b7e56ab5

1 files changed, 3 insertions, 17 deletions

diff --git a/compiler/optimizing/constant_folding.cc b/compiler/optimizing/constant_folding.cc
index 66bbf548bb..64ef17898a 100644
--- a/compiler/optimizing/constant_folding.cc
+++ b/compiler/optimizing/constant_folding.cc
@@ -32,8 +32,8 @@ namespace art HIDDEN {
 // as constants.
 class HConstantFoldingVisitor final : public HGraphDelegateVisitor {
  public:
-  HConstantFoldingVisitor(HGraph* graph, OptimizingCompilerStats* stats, bool use_all_optimizations)
-      : HGraphDelegateVisitor(graph, stats), use_all_optimizations_(use_all_optimizations) {}
+  explicit HConstantFoldingVisitor(HGraph* graph, OptimizingCompilerStats* stats)
+      : HGraphDelegateVisitor(graph, stats) {}
 
  private:
   void VisitBasicBlock(HBasicBlock* block) override;
@@ -66,9 +66,6 @@ class HConstantFoldingVisitor final : public HGraphDelegateVisitor {
   void FoldNumberOfLeadingZerosIntrinsic(HInvoke* invoke);
   void FoldNumberOfTrailingZerosIntrinsic(HInvoke* invoke);
 
-  // Use all optimizations without restrictions.
-  bool use_all_optimizations_;
-
   DISALLOW_COPY_AND_ASSIGN(HConstantFoldingVisitor);
 };
 
@@ -109,7 +106,7 @@ class InstructionWithAbsorbingInputSimplifier : public HGraphVisitor {
 
 
 bool HConstantFolding::Run() {
-  HConstantFoldingVisitor visitor(graph_, stats_, use_all_optimizations_);
+  HConstantFoldingVisitor visitor(graph_, stats_);
   // Process basic blocks in reverse post-order in the dominator tree,
   // so that an instruction turned into a constant, used as input of
   // another instruction, may possibly be used to turn that second
@@ -232,11 +229,6 @@ void HConstantFoldingVisitor::PropagateValue(HBasicBlock* starting_block,
     uses_before = variable->GetUses().SizeSlow();
   }
 
-  if (variable->GetUses().HasExactlyOneElement()) {
-    // Nothing to do, since we only have the `if (variable)` use or the `condition` use.
-    return;
-  }
-
   variable->ReplaceUsesDominatedBy(
       starting_block->GetFirstInstruction(), constant, /* strictly_dominated= */ false);
 
@@ -249,12 +241,6 @@ void HConstantFoldingVisitor::PropagateValue(HBasicBlock* starting_block,
 }
 
 void HConstantFoldingVisitor::VisitIf(HIf* inst) {
-  // This optimization can take a lot of compile time since we have a lot of If instructions in
-  // graphs.
-  if (!use_all_optimizations_) {
-    return;
-  }
-
   // Consistency check: the true and false successors do not dominate each other.
   DCHECK(!inst->IfTrueSuccessor()->Dominates(inst->IfFalseSuccessor()) &&
          !inst->IfFalseSuccessor()->Dominates(inst->IfTrueSuccessor()));