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glsl: Extract ir_unop_bitfield_reverse implementation to a separate function

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Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
This commit is contained in:
Ian Romanick
2016-07-12 17:32:24 -07:00
parent 4b0606e0a7
commit d75034b3a2
1 changed files with 27 additions and 13 deletions
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40
src/compiler/glsl/ir_constant_expression.cpp
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@@ -477,6 +477,23 @@ ir_rvalue::constant_expression_value(struct hash_table *)
return NULL; return NULL;
} }
static uint32_t
bitfield_reverse(uint32_t v)
{
/* http://graphics.stanford.edu/~seander/bithacks.html#BitReverseObvious */
uint32_t r = v; // r will be reversed bits of v; first get LSB of v
int s = sizeof(v) * CHAR_BIT - 1; // extra shift needed at end
for (v >>= 1; v; v >>= 1) {
r <<= 1;
r |= v & 1;
s--;
}
r <<= s; // shift when v's highest bits are zero
return r;
}
ir_constant * ir_constant *
ir_expression::constant_expression_value(struct hash_table *variable_context) ir_expression::constant_expression_value(struct hash_table *variable_context)
{ {
@@ -1482,20 +1499,17 @@ ir_expression::constant_expression_value(struct hash_table *variable_context)
break; break;
case ir_unop_bitfield_reverse: case ir_unop_bitfield_reverse:
/* http://graphics.stanford.edu/~seander/bithacks.html#BitReverseObvious */ for (unsigned c = 0; c < op[0]->type->components(); c++) {
for (unsigned c = 0; c < components; c++) { switch (this->type->base_type) {
unsigned int v = op[0]->value.u[c]; // input bits to be reversed case GLSL_TYPE_UINT:
unsigned int r = v; // r will be reversed bits of v; first get LSB of v data.u[c] = bitfield_reverse(op[0]->value.u[c]);
int s = sizeof(v) * CHAR_BIT - 1; // extra shift needed at end break;
case GLSL_TYPE_INT:
for (v >>= 1; v; v >>= 1) { data.i[c] = bitfield_reverse(op[0]->value.i[c]);
r <<= 1; break;
r |= v & 1; default:
s--; assert(0);
} }
r <<= s; // shift when v's highest bits are zero
data.u[c] = r;
} }
break; break;