| Message ID | 20190405225014.15236-1-paul.burton@mips.com (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | c838b580ca9dcf16b07aa72bb61a914e9db0fd2c |
| Headers | show |
| Series | [1/3] MIPS: jump_label: Remove redundant nops | expand |
Hello, Paul Burton wrote: > Both arch_static_branch() & arch_static_branch_jump() emit a control > transfer instruction (ie. branch or jump) without disabling assembler > re-ordering. As such the assembler will automatically fill their delay > slots. > > Both functions follow their branch or jump with an explicit nop that at > first appears to be there to fill the delay slot, but given that the > assembler will do that the explicit nops serve no purpose & we end up > with our branch or jump followed by 2 nops. Remove the redundant nops. > > Signed-off-by: Paul Burton <paul.burton@mips.com> Series applied to mips-next. Thanks, Paul [ This message was auto-generated; if you believe anything is incorrect then please email paul.burton@mips.com to report it. ]
diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h index e4456e450f94..df04449b261b 100644 --- a/arch/mips/include/asm/jump_label.h +++ b/arch/mips/include/asm/jump_label.h @@ -29,7 +29,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool branch) { asm_volatile_goto("1:\t" B_INSN " 2f\n\t" - "2:\tnop\n\t" + "2:\t.insn\n\t" ".pushsection __jump_table, \"aw\"\n\t" WORD_INSN " 1b, %l[l_yes], %0\n\t" ".popsection\n\t" @@ -43,7 +43,6 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch) { asm_volatile_goto("1:\tj %l[l_yes]\n\t" - "nop\n\t" ".pushsection __jump_table, \"aw\"\n\t" WORD_INSN " 1b, %l[l_yes], %0\n\t" ".popsection\n\t"
Both arch_static_branch() & arch_static_branch_jump() emit a control transfer instruction (ie. branch or jump) without disabling assembler re-ordering. As such the assembler will automatically fill their delay slots. Both functions follow their branch or jump with an explicit nop that at first appears to be there to fill the delay slot, but given that the assembler will do that the explicit nops serve no purpose & we end up with our branch or jump followed by 2 nops. Remove the redundant nops. Signed-off-by: Paul Burton <paul.burton@mips.com> --- arch/mips/include/asm/jump_label.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)