On Sat, Dec 25, 2021 at 3:28 PM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> When applying peephole optimization to transform
>
> mov imm, %reg0
> mov %reg1, %AX_REG
> imul %reg0
>
> to
>
> mov imm, %AX_REG
> imul %reg1
>
> disable peephole optimization if reg1 == AX_REG.
>
> gcc/
>
> PR bootstrap/103785
> * config/i386/i386.md: Swap operand order in comments and check
> AX input in any_mul_highpart peepholes.
>
> gcc/testsuite/
>
> PR bootstrap/103785
> * gcc.target/i386/pr103785.c: New test.
> ---
> gcc/config/i386/i386.md | 9 ++++--
> gcc/testsuite/gcc.target/i386/pr103785.c | 38 ++++++++++++++++++++++++
> 2 files changed, 44 insertions(+), 3 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/pr103785.c
>
> diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
> index 284b9507466..1c1ec227f71 100644
> --- a/gcc/config/i386/i386.md
> +++ b/gcc/config/i386/i386.md
> @@ -8578,7 +8578,7 @@
> (set_attr "mode" "SI")])
>
> ;; Highpart multiplication peephole2s to tweak register allocation.
> -;; mov %rdx,imm; mov %rax,%rdi; imulq %rdx -> mov %rax,imm; imulq %rdi
> +;; mov imm,%rdx; mov %rdi,%rax; imulq %rdx -> mov imm,%rax; imulq %rdi
> (define_peephole2
> [(set (match_operand:SWI48 0 "general_reg_operand")
> (match_operand:SWI48 1 "immediate_operand"))
> @@ -8588,7 +8588,8 @@
> (any_mul_highpart:SWI48 (match_dup 2) (match_dup 0)))
> (clobber (match_dup 2))
> (clobber (reg:CC FLAGS_REG))])]
> - "REGNO (operands[0]) != REGNO (operands[2])
> + "REGNO (operands[3]) != AX_REG
> + && REGNO (operands[0]) != REGNO (operands[2])
> && REGNO (operands[0]) != REGNO (operands[3])
> && (REGNO (operands[0]) == REGNO (operands[4])
> || peep2_reg_dead_p (3, operands[0]))"
> @@ -8608,7 +8609,9 @@
> (any_mul_highpart:SI (match_dup 2) (match_dup 0))))
> (clobber (match_dup 2))
> (clobber (reg:CC FLAGS_REG))])]
> - "REGNO (operands[0]) != REGNO (operands[2])
> + "REGNO (operands[3]) != AX_REG
Please also add TARGET_64BIT here, this DImode zero-extend pattern
applies to 64bit targets only.
OK with the above change.
Thanks,
Uros.
> + && REGNO (operands[0]) != REGNO (operands[2])
> + && REGNO (operands[2]) != REGNO (operands[3])
> && REGNO (operands[0]) != REGNO (operands[3])
> && (REGNO (operands[0]) == REGNO (operands[4])
> || peep2_reg_dead_p (3, operands[0]))"
> diff --git a/gcc/testsuite/gcc.target/i386/pr103785.c
> b/gcc/testsuite/gcc.target/i386/pr103785.c
> new file mode 100644
> index 00000000000..5503b965256
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr103785.c
> @@ -0,0 +1,38 @@
> +/* { dg-do run } */
> +/* { dg-options "-O2" } */
> +
> +#include <stdlib.h>
> +
> +struct wrapper_t
> +{
> + long k;
> + long e;
> +};
> +
> +struct wrapper_t **table;
> +
> +__attribute__ ((weak, regparm (2)))
> +void
> +update (long k, long e)
> +{
> + struct wrapper_t *elmt;
> +
> + elmt = table[k % 3079];
> + if (elmt == 0)
> + return;
> + elmt->e = e;
> +}
> +
> +int
> +main ()
> +{
> + table = (struct wrapper_t **) malloc (20 * sizeof (struct wrapper_t *));
> + for (int i = 0; i < 20; i++)
> + table[i] = (struct wrapper_t *) calloc (sizeof (struct wrapper_t), 1);
> + if (table[10]->e != 0)
> + abort ();
> + update (10, 20);
> + if (table[10]->e != 20)
> + abort ();
> + return 0;
> +}
> --
> 2.33.1
>
