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nir: Optimize umod lowering

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We don't have calculate final quotient in order to calculate unsigned
modulo result.  Once we are done with error correction we have partial
result which can be used to find out modulo operation result

Signed-off-by: Sagar Ghuge <sagar.ghuge@intel.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
This commit is contained in:
Sagar Ghuge
2019-07-22 16:30:56 -07:00
parent f8c71d7632
commit d5992ab134
1 changed files with 24 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/compiler/nir/nir_lower_idiv.c
+24 -26
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@@ -39,7 +39,7 @@
static bool
convert_instr(nir_builder *bld, nir_alu_instr *alu)
{
nir_ssa_def *numer, *denom, *af, *bf, *a, *b, *q, *r;
nir_ssa_def *numer, *denom, *af, *bf, *a, *b, *q, *r, *rt;
nir_op op = alu->op;
bool is_signed;
@@ -97,33 +97,31 @@ convert_instr(nir_builder *bld, nir_alu_instr *alu)
/* correction: if modulus >= divisor, add 1 */
r = nir_imul(bld, q, b);
r = nir_isub(bld, a, r);
r = nir_uge(bld, r, b);
r = nir_b2i32(bld, r);
q = nir_iadd(bld, q, r);
if (is_signed) {
/* fix the sign: */
r = nir_ixor(bld, numer, denom);
r = nir_ilt(bld, r, nir_imm_int(bld, 0));
b = nir_ineg(bld, q);
q = nir_bcsel(bld, r, b, q);
if (op == nir_op_imod || op == nir_op_irem) {
q = nir_imul(bld, q, denom);
q = nir_isub(bld, numer, q);
if (op == nir_op_imod) {
q = nir_bcsel(bld, nir_ieq(bld, q, nir_imm_int(bld, 0)),
nir_imm_int(bld, 0),
nir_bcsel(bld, r, nir_iadd(bld, q, denom), q));
}
}
}
rt = nir_uge(bld, r, b);
if (op == nir_op_umod) {
/* division result in q */
r = nir_imul(bld, q, b);
q = nir_isub(bld, a, r);
q = nir_bcsel(bld, rt, nir_isub(bld, r, b), r);
} else {
r = nir_b2i32(bld, rt);
q = nir_iadd(bld, q, r);
if (is_signed) {
/* fix the sign: */
r = nir_ixor(bld, numer, denom);
r = nir_ilt(bld, r, nir_imm_int(bld, 0));
b = nir_ineg(bld, q);
q = nir_bcsel(bld, r, b, q);
if (op == nir_op_imod || op == nir_op_irem) {
q = nir_imul(bld, q, denom);
q = nir_isub(bld, numer, q);
if (op == nir_op_imod) {
q = nir_bcsel(bld, nir_ieq(bld, q, nir_imm_int(bld, 0)),
nir_imm_int(bld, 0),
nir_bcsel(bld, r, nir_iadd(bld, q, denom), q));
}
}
}
}
assert(alu->dest.dest.is_ssa);