/* https://bugs.kde.org/show_bug.cgi?id=308627 */ #include "../../memcheck.h" #include <stdio.h> typedef unsigned long ULong; typedef struct { ULong w64[2]; /* Note: little-endian */ } V128; static int getMSBs16x8(V128 v) { int result; __asm__("movups %1,%%xmm6\n" "\tpmovmskb %%xmm6,%0\n" : "=r" (result) : "m" (v) : "xmm6"); return result; } /* Set the V bits on the data at "addr". Note the convention: A zero bit means "defined"; 1 means "undefined". */ static void set_vbits(V128 *addr, V128 vbits) { int i; for (i=0 ; i<2 ; ++i) { (void)VALGRIND_SET_VBITS(&addr->w64[i], &vbits.w64[i], sizeof(vbits.w64[i])); } } static void print(V128 vbits, V128 val, int bit, int result) { printf("vbits=0x%016lx%016lx val=0x%016lx%016lx bit=%d result=%d\n", vbits.w64[1], vbits.w64[0], val.w64[1], val.w64[0], bit, result); } /* Use a value that we know is invalid. */ static void use(int index, int invalid) { /* Convince GCC it does not know what is in "invalid" so it cannot possibly optimize away the conditional branch below. */ __asm__ ("" : "=r" (invalid) : "0" (invalid)); /* Create a conditional branch on which our output depends, so that memcheck cannot possibly optimize it away, either. */ fprintf(stderr, "%d: Invalid value is %s\n", index, invalid ? "true" : "false"); } static void doit(ULong vbits_hi, ULong vbits_lo, ULong val_hi, ULong val_lo) { V128 vbits = { { vbits_lo, vbits_hi } }; V128 val = { { val_lo, val_hi } }; /* Since we are about to mark "val" partially undefined, make a copy that we can use without generating a memcheck warning. */ V128 val_copy = val; set_vbits(&val, vbits); int result = getMSBs16x8(val); int vbits_mask = getMSBs16x8(vbits); int bit = 0; ULong mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); bit = 1; mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); bit = 2; mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); bit = 3; mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); bit = 4; mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); bit = 5; mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); bit = 6 ; mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); bit = 7 ; mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); bit = 8 ; mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); bit = 9 ; mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); bit = 10 ; mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); bit = 11 ; mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); bit = 12 ; mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); bit = 13 ; mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); bit = 14 ; mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); bit = 15 ; mask = (1UL << bit); if ((vbits_mask & mask) == 0) print(vbits, val_copy, bit, result & mask); else use(bit, result & mask); } int main(int argc, char *argv[]) { doit(0x0000000000000000, 0x0000000000000000, 0x0000000000000000, 0x0000000000000000); doit(0x0707070707070707, 0x0707070707070707, 0x0000000000000000, 0x0000000000000000); doit(0x8080808080808080, 0x8080808080808080, 0x0000000000000000, 0x0000000000000000); doit(0x13579BDF02468ACE, 0xFEDCBA9876543210, 0xFEEDFACEDEADBEEF, 0xFEE1DEADDABBAD00); return 0; }