typedef unsigned long long uint64_t; void abort (void); #define BASE 0x1234567812345678ull #define DEF_BBIT_TAKEN(BRANCH_IF, BIT) \ int bbit_is_taken_##BRANCH_IF##_##BIT (volatile uint64_t *p) \ { \ int ret; \ asm (".set push \n\t" \ ".set noreorder \n\t" \ "bbit" #BRANCH_IF " %1, " #BIT ", 1f \n\t" \ "nop \n\t" \ "li %0, 0 \n\t" \ "b 2f \n\t" \ "nop \n\t" \ "1: \n\t" \ "li %0, 1 \n\t" \ "2: \n\t" \ ".set pop" \ : "=r"(ret) : "r"(*p)); \ return ret; \ } \ volatile uint64_t taken_##BRANCH_IF##_##BIT = \ BASE & (~(1ull << BIT)) | ((uint64_t) BRANCH_IF << BIT); \ volatile uint64_t not_taken_##BRANCH_IF##_##BIT = \ BASE & (~(1ull << BIT)) | (((uint64_t) !BRANCH_IF) << BIT); DEF_BBIT_TAKEN (0, 10); DEF_BBIT_TAKEN (0, 36); DEF_BBIT_TAKEN (1, 20); DEF_BBIT_TAKEN (1, 49); #define EXPECT(X) if (!(X)) abort (); main () { EXPECT (bbit_is_taken_0_10 (&taken_0_10)); EXPECT (!bbit_is_taken_0_10 (¬_taken_0_10)); EXPECT (bbit_is_taken_0_36 (&taken_0_36)); EXPECT (!bbit_is_taken_0_36 (¬_taken_0_36)); EXPECT (bbit_is_taken_1_20 (&taken_1_20)); EXPECT (!bbit_is_taken_1_20 (¬_taken_1_20)); EXPECT (bbit_is_taken_1_49 (&taken_1_49)); EXPECT (!bbit_is_taken_1_49 (¬_taken_1_49)); }