Re: [PATCH 2/2] gdb/record: add support for BMI2 instructions

[Guinevere Larsen <guinevere@redhat.com>]

I'm pushing this series with a trivial change to the test, fixing an 
oversight I had when writing the original patch

On 6/17/26 11:00 AM, Guinevere Larsen wrote:
> This commit adds support for recording all instructions in the Bit
> Manipulation Instruction set 2, for x86 cpus. The specific instructions
> are:
>
> * mulx
> * pdep
> * pext
> * rorx
> * sarx
> * sh[r|l]x
> * bzhi
>
> And adds them to the AVX test, for the same reason as the previous
> commit.
> ---
>   gdb/i386-tdep.c                                | 18 ++++++++++++++++--
>   gdb/testsuite/gdb.reverse/i386-avx-reverse.c   | 13 +++++++++++++
>   gdb/testsuite/gdb.reverse/i386-avx-reverse.exp | 14 ++++++++++++++
>   3 files changed, 43 insertions(+), 2 deletions(-)
>
> diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
> index 8b4dfb43f61..189a711fd81 100644
> --- a/gdb/i386-tdep.c
> +++ b/gdb/i386-tdep.c
> @@ -5128,7 +5128,7 @@ i386_record_vex (struct i386_record_s *ir, uint8_t vex_w, uint8_t vex_r,
>       case 0xf2:	/* VPSLLD, dynamic shift and ANDN.  */
>       case 0xf3:	/* VPSLLQ, dynamic shift and BLSI, BLSR and BLSMSK.  */
>       case 0xf4:	/* VPMULUDQ  */
> -    case 0xf6:	/* VPSADBW.  */
> +    case 0xf6:	/* VPSADBW or MULX.  */
>       case 0xfc:	/* VPADDB  */
>       case 0xfd:	/* VPADDW  */
>       case 0xfe:	/* VPADDD  */
> @@ -5152,6 +5152,15 @@ i386_record_vex (struct i386_record_s *ir, uint8_t vex_w, uint8_t vex_r,
>   	    record_full_arch_list_add_reg
>   	      (ir->regcache, ir->regmap[X86_RECORD_EFLAGS_REGNUM]);
>   	  }
> +	else if (opcode == 0xf6 && ir->map_select == 2)
> +	  {
> +	    record_full_arch_list_add_reg (ir->regcache,
> +					   ir->regmap[X86_RECORD_REAX_REGNUM
> +						      + ir->vvvv]);
> +	    record_full_arch_list_add_reg (ir->regcache,
> +					   ir->regmap[X86_RECORD_REAX_REGNUM
> +						      + reg_offset]);
> +	  }
>   	else
>   	  {
>   	    /* This set of instructions all share the same exact way to
> @@ -5164,11 +5173,16 @@ i386_record_vex (struct i386_record_s *ir, uint8_t vex_w, uint8_t vex_r,
>         }
>         break;
>   
> -    case 0xf7:	/* BEXTR.  */
> +    case 0xf0:	/* RORX.  */
> +    case 0xf5:	/* PDEP or PEXT or BZHI.  */
> +    case 0xf7:	/* BEXTR or SARX or SHLX or SHRX.  */
>         i386_record_modrm (ir);
>         record_full_arch_list_add_reg (ir->regcache,
>   				     ir->regmap[X86_RECORD_REAX_REGNUM
>   						+ ir->reg + vex_r * 8]);
> +      if (opcode == 0xf5 && ir->pp == 0)
> +	record_full_arch_list_add_reg (ir->regcache,
> +				       ir->regmap[X86_RECORD_EFLAGS_REGNUM]);
>         break;
>   
>       case 0x2e: /* VUCOMIS[S|D].  */
> diff --git a/gdb/testsuite/gdb.reverse/i386-avx-reverse.c b/gdb/testsuite/gdb.reverse/i386-avx-reverse.c
> index 190bc6f4a7a..4e4428f695a 100644
> --- a/gdb/testsuite/gdb.reverse/i386-avx-reverse.c
> +++ b/gdb/testsuite/gdb.reverse/i386-avx-reverse.c
> @@ -799,6 +799,19 @@ bmi_test ()
>     asm volatile ("tzcnt %eax, %ebx");
>     asm volatile ("tzcnt %ax, %r8w");
>   
> +  asm volatile ("mulx %eax, %ebx, %ecx");
> +  asm volatile ("mulx %ebx, %ecx, %ebx");
> +
> +  asm volatile ("pdep %r8, %rcx, %rbx");
> +  asm volatile ("pext %edx, %ecx, %ebx");
> +  asm volatile ("rorx $10, %r8, %rbx");
> +  asm volatile ("sarx %edx, %ebx, %eax");
> +  asm volatile ("shlx %eax, %ecx, %ebx");
> +  asm volatile ("shrx %r8d, %eax, %ecx");
> +
> +  asm volatile ("bzhi %edx, %ebx, %r8d");
> +  asm volatile ("bzhi %rax, %rcx, %r8");
> +
>     return 0; /* end bmi_test  */
>   }
>   
> diff --git a/gdb/testsuite/gdb.reverse/i386-avx-reverse.exp b/gdb/testsuite/gdb.reverse/i386-avx-reverse.exp
> index e1780267ad0..a482142edde 100644
> --- a/gdb/testsuite/gdb.reverse/i386-avx-reverse.exp
> +++ b/gdb/testsuite/gdb.reverse/i386-avx-reverse.exp
> @@ -1206,9 +1206,23 @@ gdb_test_no_output \
>       "set \$eax = 0x1312" "set eax for bmi test"
>   gdb_test_no_output "set \$ebx = 0xdeadbeef" "set ebx for bmi test"
>   gdb_test_no_output "set \$ecx = 0xcafeface" "set ecx for bmi test"
> +gdb_test_no_output "set \$edx = 0x2337" "set edx for bmi test"
>   
>   if {[record_full_function "bmi"] == true} {
>   
> +    test_one_general_register "bzhi" "r8" "0xe884173"
> +    test_one_general_register "bzhi" "r8" "0x0"
> +
> +    test_one_general_register "shrx" "ecx" "0x0"
This was updated to look for 0xe884173

-- 
Cheers,
Guinevere Larsen
it/its
she/her (deprecated)

> +    test_one_general_register "shlx" "ebx" "0x0"
> +    test_one_general_register "sarx" "eax" "0x3"
> +    test_one_general_register "rorx" "ebx" "0x3b"
> +    test_one_general_register "pext" "ebx" "0x0"
> +    test_one_general_register "pdep" "ebx" "0x0"
> +
> +    test_one_general_register "mulx" "ecx" "0x0"
> +    test_one_general_register "mulx" "ebx" "0x0"
> +
>       test_one_general_register "tzcnt" "r8" "0x3e"
>       test_one_general_register "tzcnt" "ebx" "0xe"
>       test_one_general_register "tzcnt" "ecx" "0x1e"