[11u] RFR 8255550: x86: Assembler::cmpq(Address dst, Register src) encoding is incorrect

[Zhengyu Gu]

Looks good.

-Zhengyu

On 11/12/20 10:24 AM, Aleksey Shipilev wrote:
> Original bug:
>    https://bugs.openjdk.java.net/browse/JDK-8255550
>    https://git.openjdk.java.net/jdk/commit/9e5bbff5
> 
> Backporting this for parity in 11u. The code shape is a bit different 
> due to clean ups in later JDK. 11u patch is:
> 
> diff -r 36e0ac0a01ad src/hotspot/cpu/x86/assembler_x86.cpp
> --- a/src/hotspot/cpu/x86/assembler_x86.cpp     Wed May 20 11:29:11 2020 
> -0700
> +++ b/src/hotspot/cpu/x86/assembler_x86.cpp     Thu Nov 12 15:47:56 2020 
> +0100
> @@ -8588,7 +8588,7 @@
>   void Assembler::cmpq(Address dst, Register src) {
>     InstructionMark im(this);
>     prefixq(dst, src);
> -  emit_int8(0x3B);
> +  emit_int8(0x39);
>     emit_operand(src, dst);
>   }
> 
> Testing: checking code usages (none!), tier1
>