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nir/algebraic: add patterns for a >> #b << #b

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Fixes compilation of a Battlefront 2 shader with ACO by removing VGPR
spilling. The reassociation makes it worse on LLVM though.

pipeline-db (ACO):
Totals from affected shaders:
SGPRS: 10704 -> 10688 (-0.15 %)
VGPRS: 18736 -> 18528 (-1.11 %)
Spilled SGPRs: 70 -> 70 (0.00 %)
Spilled VGPRs: 0 -> 0 (0.00 %)
Private memory VGPRs: 0 -> 0 (0.00 %)
Scratch size: 0 -> 0 (0.00 %) dwords per thread
Code Size: 909696 -> 885796 (-2.63 %) bytes
LDS: 225 -> 225 (0.00 %) blocks
Max Waves: 1115 -> 1129 (1.26 %)

pipeline-db (LLVM):
Totals from affected shaders:
SGPRS: 8472 -> 8424 (-0.57 %)
VGPRS: 14284 -> 14368 (0.59 %)
Spilled SGPRs: 0 -> 0 (0.00 %)
Spilled VGPRs: 442 -> 503 (13.80 %)
Private memory VGPRs: 0 -> 0 (0.00 %)
Scratch size: 268 -> 396 (47.76 %) dwords per thread
Code Size: 862568 -> 853028 (-1.11 %) bytes
LDS: 0 -> 0 (0.00 %) blocks
Max Waves: 971 -> 964 (-0.72 %)

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/2271>
This commit is contained in:
Rhys Perry 2019-10-09 15:03:45 +01:00 • committed by Marge Bot
parent 6aecc316c0
commit 5476d18183
2 changed files with 42 additions and 0 deletions
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16
src/compiler/nir/nir_opt_algebraic.py
View file

@ -255,6 +255,22 @@ for s in [8, 16, 32, 64]:
(ishr, a, ('imin', ('iadd', ('iand', b, mask), ('iand', c, mask)), s - 1))),
])
# Optimize a pattern of address calculation created by DXVK where the offset is
# divided by 4 and then multipled by 4. This can be turned into an iand and the
# additions before can be reassociated to CSE the iand instruction.
for log2 in range(1, 7): # powers of two from 2 to 64
v = 1 << log2
mask = 0xffffffff & ~(v - 1)
b_is_multiple = '#b(is_unsigned_multiple_of_{})'.format(v)
optimizations.extend([
# 'a >> #b << #b' -> 'a & ~((1 << #b) - 1)'
(('ishl@32', ('ushr@32', a, log2), log2), ('iand', a, mask)),
# Reassociate for improved CSE
(('iand@32', ('iadd@32', a, b_is_multiple), mask), ('iadd', ('iand', a, mask), b)),
])
optimizations.extend([
# This is common for address calculations. Reassociating may enable the
# 'a<<c' to be CSE'd. It also helps architectures that have an ISHLADD

26
src/compiler/nir/nir_search_helpers.h
View file

@ -90,6 +90,32 @@ is_neg_power_of_two(UNUSED struct hash_table *ht, nir_alu_instr *instr,
return true;
}
#define MULTIPLE(test) \
static inline bool \
is_unsigned_multiple_of_ ## test(UNUSED struct hash_table *ht, nir_alu_instr *instr, \
unsigned src, unsigned num_components, \
const uint8_t *swizzle) \
{ \
/* only constant srcs: */ \
if (!nir_src_is_const(instr->src[src].src)) \
return false; \
\
for (unsigned i = 0; i < num_components; i++) { \
uint64_t val = nir_src_comp_as_uint(instr->src[src].src, swizzle[i]); \
if (val % test != 0) \
return false; \
} \
\
return true; \
}
MULTIPLE(2)
MULTIPLE(4)
MULTIPLE(8)
MULTIPLE(16)
MULTIPLE(32)
MULTIPLE(64)
static inline bool
is_zero_to_one(UNUSED struct hash_table *ht, nir_alu_instr *instr, unsigned src,
unsigned num_components,