ARM: Port instr simplification of array accesses.
After changing the addressing mode for array accesses (in
https://android-review.googlesource.com/248406) the 'add'
instruction that calculates the base address for the array can be
shared across accesses to the same array.
Before https://android-review.googlesource.com/248406:
add IP, r[Array], r[Index0], LSL #2
ldr r0, [IP, #12]
add IP, r[Array], r[Index1], LSL #2
ldr r0, [IP, #12]
Before this CL:
add IP. r[Array], #12
ldr r0, [IP, r[Index0], LSL #2]
add IP. r[Array], #12
ldr r0, [IP, r[Index1], LSL #2]
After this CL:
add IP. r[Array], #12
ldr r0, [IP, r[Index0], LSL #2]
ldr r0, [IP, r[Index1], LSL #2]
Link to the original optimization:
https://android-review.googlesource.com/#/c/127310/
Test: Run ART test suite on Nexus 6.
Change-Id: Iee26f9a0a7ca46abb90e3f60d19d22dc8dee4d8f
diff --git a/compiler/optimizing/nodes_shared.h b/compiler/optimizing/nodes_shared.h
index f2d5cf3..8bd8667 100644
--- a/compiler/optimizing/nodes_shared.h
+++ b/compiler/optimizing/nodes_shared.h
@@ -113,6 +113,34 @@
DISALLOW_COPY_AND_ASSIGN(HBitwiseNegatedRight);
};
+
+// This instruction computes an intermediate address pointing in the 'middle' of an object. The
+// result pointer cannot be handled by GC, so extra care is taken to make sure that this value is
+// never used across anything that can trigger GC.
+class HIntermediateAddress FINAL : public HExpression<2> {
+ public:
+ HIntermediateAddress(HInstruction* base_address, HInstruction* offset, uint32_t dex_pc)
+ : HExpression(Primitive::kPrimNot, SideEffects::DependsOnGC(), dex_pc) {
+ SetRawInputAt(0, base_address);
+ SetRawInputAt(1, offset);
+ }
+
+ bool CanBeMoved() const OVERRIDE { return true; }
+ bool InstructionDataEquals(const HInstruction* other ATTRIBUTE_UNUSED) const OVERRIDE {
+ return true;
+ }
+ bool IsActualObject() const OVERRIDE { return false; }
+
+ HInstruction* GetBaseAddress() const { return InputAt(0); }
+ HInstruction* GetOffset() const { return InputAt(1); }
+
+ DECLARE_INSTRUCTION(IntermediateAddress);
+
+ private:
+ DISALLOW_COPY_AND_ASSIGN(HIntermediateAddress);
+};
+
+
} // namespace art
#endif // ART_COMPILER_OPTIMIZING_NODES_SHARED_H_