fdo-mirrors/mesa
1
0
Fork 0
mirror of https://gitlab.freedesktop.org/mesa/mesa.git synced 2026-01-30 02:50:35 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions 3

nir/opcodes: Avoid technical UB left shifting ints.

Browse source 
We all know that (int)0xff << 24 is fine, but UBSan doesn't like it.
These were triggered by nir_opt_algebraic_pattern_tests.

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39076>
This commit is contained in:
Emma Anholt 2026-01-07 09:14:31 -08:00 • committed by Marge Bot
parent 079d416e99
commit 8529aaa399
1 changed files with 5 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

10
src/compiler/nir/nir_opcodes.py
View file

@ -590,7 +590,7 @@ dst = -1;
/* We are looking for the highest bit that's not the same as the sign bit. */
uint32_t sign = src0 & 0x80000000u;
for (int bit = 0; bit < 32; bit++) {
if (((src0 << bit) & 0x80000000u) != sign) {
if ((((uint32_t)src0 << bit) & 0x80000000u) != sign) {
dst = bit;
break;
}
@ -1228,7 +1228,7 @@ if (bits == 0) {
dst = 0;
poison = true;
} else {
dst = (base << (32 - offset - bits)) >> (32 - bits); /* use sign-extending shift */
dst = (int32_t)((uint32_t)base << (32 - offset - bits)) >> (32 - bits); /* use sign-extending shift */
}
""")
@ -1350,7 +1350,7 @@ binop("amul", tint, _2src_commutative + associative, "src0 * src1")
# multiplication (imul) on Freedreno backend..
opcode("imadsh_mix16", 0, tint32,
[0, 0, 0], [tint32, tint32, tint32], False, "", """
dst = ((((src0 & 0x0000ffff) << 16) * (src1 & 0xffff0000)) >> 16) + src2;
dst = (((int32_t)(((uint32_t)src0 & 0x0000ffff) << 16) * (src1 & 0xffff0000)) >> 16) + src2;
""")
# ir3-specific instruction that maps directly to ir3 mad.s24.
@ -1528,7 +1528,7 @@ opcode("lea_nv", 0, tuint, [0, 0, 0], [tuint, tuint, tuint32], False,
# 24b multiply into 32b result (with sign extension)
binop("imul24", tint32, _2src_commutative,
"(((int32_t)src0 << 8) >> 8) * (((int32_t)src1 << 8) >> 8)")
"util_mask_sign_extend(src0, 24) * util_mask_sign_extend(src1, 24)")
# unsigned 24b multiply into 32b result plus 32b int
triop("umad24", tuint32, _2src_commutative,
@ -1574,7 +1574,7 @@ for (int i = 0; i < 32; i += 8) {
int src0_chan = (src0 >> i) & 0xff;
int src1_chan = (src1 >> i) & 0xff;
if (src0_chan > src1_chan)
dst |= (src0_chan - src1_chan) << i;
dst |= (uint32_t)(src0_chan - src1_chan) << i;
}
""")