Index: lib/Target/AArch64/AArch64InstrInfo.cpp =================================================================== --- lib/Target/AArch64/AArch64InstrInfo.cpp +++ lib/Target/AArch64/AArch64InstrInfo.cpp @@ -620,6 +620,12 @@ return canBeExpandedToORR(MI, 32); case AArch64::MOVi64imm: return canBeExpandedToORR(MI, 64); + + // It is cheap to move #0 to float registers if the subtarget has + // ZeroCycleZeroing feature. + case AArch64::FMOVS0: + case AArch64::FMOVD0: + return Subtarget.hasZeroCycleZeroing(); } llvm_unreachable("Unknown opcode to check as cheap as a move!"); Index: test/CodeGen/AArch64/arm64-zero-cycle-zeroing.ll =================================================================== --- test/CodeGen/AArch64/arm64-zero-cycle-zeroing.ll +++ test/CodeGen/AArch64/arm64-zero-cycle-zeroing.ll @@ -13,9 +13,9 @@ ; CYCLONE: movi.2d v2, #0000000000000000 ; CYCLONE: movi.2d v3, #0000000000000000 ; KRYO: movi v0.2d, #0000000000000000 -; KRYO: mov v1.16b, v0.16b -; KRYO: mov v2.16b, v0.16b -; KRYO: mov v3.16b, v0.16b +; KRYO: movi v1.2d, #0000000000000000 +; KRYO: movi v2.2d, #0000000000000000 +; KRYO: movi v3.2d, #0000000000000000 tail call void @bar(double 0.000000e+00, double 0.000000e+00, double 0.000000e+00, double 0.000000e+00) nounwind ret void } @@ -46,7 +46,7 @@ ; CYCLONE: movi.2d v0, #0000000000000000 ; CYCLONE: movi.2d v1, #0000000000000000 ; KRYO: movi v0.2d, #0000000000000000 -; KRYO: mov v1.16b, v0.16b +; KRYO: movi v1.2d, #0000000000000000 tail call void @barf(float 0.000000e+00, float 0.000000e+00) nounwind ret void }