ART: Simplify HRem to reuse existing HDiv

A pattern seen in libcore and SPECjvm2008 workloads is a pair of HRem/HDiv
having the same dividend and divisor. The code generator processes
them separately and generates duplicated instructions calculating HDiv.

This CL adds detection of such a pattern to the instruction simplifier.
This optimization affects HInductionVarAnalysis and HLoopOptimization
preventing some loop optimizations. To avoid this the instruction simplifier
has the loop_friendly mode which means not to optimize HRems if they are in a loop.

A microbenchmark run on Pixel 3 shows the following improvements:

            | little cores | big cores
arm32 Int32 |  +21%        |  +40%
arm32 Int64 |  +46%        |  +44%
arm64 Int32 |  +27%        |  +14%
arm64 Int64 |  +33%        |  +27%

Test: 411-checker-instruct-simplifier-hrem
Test: test.py --host --optimizing --jit --gtest --interpreter
Test: test.py --target --optimizing --jit --interpreter
Test: run-gtests.sh

Change-Id: I376a1bd299d7fe10acad46771236edd5f85dfe56

1 files changed, 7 insertions, 2 deletions

diff --git a/compiler/optimizing/instruction_simplifier.h b/compiler/optimizing/instruction_simplifier.h
index 982a24a6f0..feea771096 100644
--- a/compiler/optimizing/instruction_simplifier.h
+++ b/compiler/optimizing/instruction_simplifier.h
@@ -40,9 +40,11 @@ class InstructionSimplifier : public HOptimization {
   InstructionSimplifier(HGraph* graph,
                         CodeGenerator* codegen,
                         OptimizingCompilerStats* stats = nullptr,
-                        const char* name = kInstructionSimplifierPassName)
+                        const char* name = kInstructionSimplifierPassName,
+                        bool use_all_optimizations = false)
       : HOptimization(graph, name, stats),
-        codegen_(codegen) {}
+        codegen_(codegen),
+        use_all_optimizations_(use_all_optimizations) {}
 
   static constexpr const char* kInstructionSimplifierPassName = "instruction_simplifier";
 
@@ -51,6 +53,9 @@ class InstructionSimplifier : public HOptimization {
  private:
   CodeGenerator* codegen_;
 
+  // Use all optimizations without restrictions.
+  bool use_all_optimizations_;
+
   DISALLOW_COPY_AND_ASSIGN(InstructionSimplifier);
 };