/* snip */
>
> diff --git a/gcc/testsuite/gcc.target/loongarch/add-const.c b/gcc/testsuite/gcc.target/loongarch/add-const.c
> new file mode 100644
> index 00000000000..3a9f72fe83d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/loongarch/add-const.c
> @@ -0,0 +1,47 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O -mabi=lp64d" } */
> +
> +/* None of these functions should load the const operand into a temp
> +   register.  */
> +
> +/* { dg-final { scan-assembler-not "add\\.[dw]" } } */
> +
> +unsigned long f01 (unsigned long x) { return x + 1; }
> +unsigned long f02 (unsigned long x) { return x - 1; }
> +unsigned long f03 (unsigned long x) { return x + 2047; }
> +unsigned long f04 (unsigned long x) { return x + 4094; }
> +unsigned long f05 (unsigned long x) { return x - 2048; }
> +unsigned long f06 (unsigned long x) { return x - 4096; }
> +unsigned long f07 (unsigned long x) { return x + 0x7fff0000; }
> +unsigned long f08 (unsigned long x) { return x - 0x80000000l; }
> +unsigned long f09 (unsigned long x) { return x + 0x7fff0000l * 2; }
> +unsigned long f10 (unsigned long x) { return x - 0x80000000l * 2; }
> +unsigned long f11 (unsigned long x) { return x - 0x80000000l * 2; }
These two test cases are duplicates.
> +unsigned long f12 (unsigned long x) { return x + 0x7fff0000 + 0x1; }
> +unsigned long f13 (unsigned long x) { return x + 0x7fff0000 - 0x1; }
> +unsigned long f14 (unsigned long x) { return x + 0x7fff0000 + 0x7ff; }
> +unsigned long f15 (unsigned long x) { return x + 0x7fff0000 - 0x800; }
> +unsigned long f16 (unsigned long x) { return x - 0x80000000l - 1; }
> +unsigned long f17 (unsigned long x) { return x - 0x80000000l + 1; }
> +unsigned long f18 (unsigned long x) { return x - 0x80000000l - 0x800; }
> +unsigned long f19 (unsigned long x) { return x - 0x80000000l + 0x7ff; }
> +
> +unsigned int g01 (unsigned int x) { return x + 1; }
> +unsigned int g02 (unsigned int x) { return x - 1; }
> +unsigned int g03 (unsigned int x) { return x + 2047; }
> +unsigned int g04 (unsigned int x) { return x + 4094; }
> +unsigned int g05 (unsigned int x) { return x - 2048; }
> +unsigned int g06 (unsigned int x) { return x - 4096; }
> +unsigned int g07 (unsigned int x) { return x + 0x7fff0000; }
> +unsigned int g08 (unsigned int x) { return x - 0x80000000l; }
> +unsigned int g09 (unsigned int x) { return x + 0x7fff0000l * 2; }
> +unsigned int g10 (unsigned int x) { return x - 0x80000000l * 2; }
> +unsigned int g11 (unsigned int x) { return x - 0x80000000l * 2; }

Ditto.

I found that adding this log test case 
gcc.target/loongarch/stack-check-cfa-1.c and 
gcc.target/loongarch/stack-check-cfa-2.c test failed.

Although the test fails, the generated assembly code is better, and 
there is no problem with the logic of the assembly code. I haven't 
checked the reason for this yet.

Otherwise LGTM, thanks!