ART: ARM64: Optimize frame size for SIMD graphs.

For SIMD graphs allocate 64 bit instead of 128 bit on stack for
each FP register to be preserved by the callee in the frame entry
as ABI suggests (currently 64-bit registers are preserved but
more space on stack is allocated).

Note: slow paths still require spilling full 128-bit Q-Registers
for SIMD graphs due to register allocator restrictions.

Test: test-art-target.
Change-Id: Ie0b12e4b769158445f3d0f4562c70d4fb0ea7744

1 files changed, 16 insertions, 2 deletions

diff --git a/compiler/optimizing/code_generator.h b/compiler/optimizing/code_generator.h
index d932c6afb0..917d97de1b 100644
--- a/compiler/optimizing/code_generator.h
+++ b/compiler/optimizing/code_generator.h
@@ -222,7 +222,19 @@ class CodeGenerator : public DeletableArenaObject<kArenaAllocCodeGenerator> {
   virtual Assembler* GetAssembler() = 0;
   virtual const Assembler& GetAssembler() const = 0;
   virtual size_t GetWordSize() const = 0;
-  virtual size_t GetFloatingPointSpillSlotSize() const = 0;
+
+  // Get FP register width in bytes for spilling/restoring in the slow paths.
+  //
+  // Note: In SIMD graphs this should return SIMD register width as all FP and SIMD registers
+  // alias and live SIMD registers are forced to be spilled in full size in the slow paths.
+  virtual size_t GetSlowPathFPWidth() const {
+    // Default implementation.
+    return GetCalleePreservedFPWidth();
+  }
+
+  // Get FP register width required to be preserved by the target ABI.
+  virtual size_t GetCalleePreservedFPWidth() const  = 0;
+
   virtual uintptr_t GetAddressOf(HBasicBlock* block) = 0;
   void InitializeCodeGeneration(size_t number_of_spill_slots,
                                 size_t maximum_safepoint_spill_size,
@@ -675,7 +687,7 @@ class CodeGenerator : public DeletableArenaObject<kArenaAllocCodeGenerator> {
   }
 
   uint32_t GetFpuSpillSize() const {
-    return POPCOUNT(fpu_spill_mask_) * GetFloatingPointSpillSlotSize();
+    return POPCOUNT(fpu_spill_mask_) * GetCalleePreservedFPWidth();
   }
 
   uint32_t GetCoreSpillSize() const {
@@ -793,6 +805,8 @@ class CodeGenerator : public DeletableArenaObject<kArenaAllocCodeGenerator> {
   std::unique_ptr<CodeGenerationData> code_generation_data_;
 
   friend class OptimizingCFITest;
+  ART_FRIEND_TEST(CodegenTest, ARM64FrameSizeSIMD);
+  ART_FRIEND_TEST(CodegenTest, ARM64FrameSizeNoSIMD);
 
   DISALLOW_COPY_AND_ASSIGN(CodeGenerator);
 };