diff options
| -rw-r--r-- | src/compiler/nir/nir_range_analysis.c | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/src/compiler/nir/nir_range_analysis.c b/src/compiler/nir/nir_range_analysis.c index 6dfaea167ac..7fbf4217239 100644 --- a/src/compiler/nir/nir_range_analysis.c +++ b/src/compiler/nir/nir_range_analysis.c @@ -31,6 +31,12 @@ * the result. */ +static bool +is_not_negative(enum ssa_ranges r) +{ + return r == gt_zero || r == ge_zero || r == eq_zero; +} + static void * pack_data(const struct ssa_result_range r) { @@ -722,6 +728,66 @@ analyze_expression(const nir_alu_instr *instr, unsigned src, r = (struct ssa_result_range){le_zero, false}; break; + case nir_op_fpow: { + /* Due to flush-to-zero semanatics of floating-point numbers with very + * small mangnitudes, we can never really be sure a result will be + * non-zero. + * + * NIR uses pow() and powf() to constant evaluate nir_op_fpow. The man + * page for that function says: + * + * If y is 0, the result is 1.0 (even if x is a NaN). + * + * gt_zero: pow(*, eq_zero) + * | pow(eq_zero, lt_zero) # 0^-y = +inf + * | pow(eq_zero, le_zero) # 0^-y = +inf or 0^0 = 1.0 + * ; + * + * eq_zero: pow(eq_zero, gt_zero) + * ; + * + * ge_zero: pow(gt_zero, gt_zero) + * | pow(gt_zero, ge_zero) + * | pow(gt_zero, lt_zero) + * | pow(gt_zero, le_zero) + * | pow(gt_zero, ne_zero) + * | pow(gt_zero, unknown) + * | pow(ge_zero, gt_zero) + * | pow(ge_zero, ge_zero) + * | pow(ge_zero, lt_zero) + * | pow(ge_zero, le_zero) + * | pow(ge_zero, ne_zero) + * | pow(ge_zero, unknown) + * | pow(eq_zero, ge_zero) # 0^0 = 1.0 or 0^+y = 0.0 + * | pow(eq_zero, ne_zero) # 0^-y = +inf or 0^+y = 0.0 + * | pow(eq_zero, unknown) # union of all other y cases + * ; + * + * All other cases are unknown. + * + * We could do better if the right operand is a constant, integral + * value. + */ + static const enum ssa_ranges table[last_range + 1][last_range + 1] = { + /* left\right unknown lt_zero le_zero gt_zero ge_zero ne_zero eq_zero */ + /* unknown */ { _______, _______, _______, _______, _______, _______, gt_zero }, + /* lt_zero */ { _______, _______, _______, _______, _______, _______, gt_zero }, + /* le_zero */ { _______, _______, _______, _______, _______, _______, gt_zero }, + /* gt_zero */ { ge_zero, ge_zero, ge_zero, ge_zero, ge_zero, ge_zero, gt_zero }, + /* ge_zero */ { ge_zero, ge_zero, ge_zero, ge_zero, ge_zero, ge_zero, gt_zero }, + /* ne_zero */ { _______, _______, _______, _______, _______, _______, gt_zero }, + /* eq_zero */ { ge_zero, gt_zero, gt_zero, eq_zero, ge_zero, ge_zero, gt_zero }, + }; + + const struct ssa_result_range left = analyze_expression(alu, 0, ht); + const struct ssa_result_range right = analyze_expression(alu, 1, ht); + + r.is_integral = left.is_integral && right.is_integral && + is_not_negative(right.range); + r.range = table[left.range][right.range]; + break; + } + case nir_op_ffma: { const struct ssa_result_range first = analyze_expression(alu, 0, ht); const struct ssa_result_range second = analyze_expression(alu, 1, ht); |