From: Ian Romanick <ian.d.romanick@intel.com>
Date: Tue, 24 Sep 2019 22:55:49 +0000 (-0700)
Subject: nir/range-analysis: Bail if the types don't match
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=018d2b524ad399ef9ea6d31de98de7078d702980;p=mesa.git

nir/range-analysis: Bail if the types don't match

Some shaders are hurt by this change because now a
load_const(0x00000000) is not recognized as eq_zero when loaded as a
float.  This behavior is restored in a later patch (nir/range-analysis:
Use types to provide better ranges from bcsel and mov).

v2: Add a comment about reinterpretation of int/uint/bool.  Suggested by
Caio.  Rewrite condition the check for types being float versus checking
for types not being all the things that aren't float.

Fixes: 405de7ccb6c ("nir/range-analysis: Rudimentary value range analysis pass")
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>

All Gen7+ platforms had similar results. (Ice Lake shown)
total instructions in shared programs: 16327543 -> 16328255 (<.01%)
instructions in affected programs: 55928 -> 56640 (1.27%)
helped: 0
HURT: 208
HURT stats (abs)   min: 1 max: 16 x̄: 3.42 x̃: 3
HURT stats (rel)   min: 0.33% max: 6.74% x̄: 1.31% x̃: 1.12%
95% mean confidence interval for instructions value: 3.06 3.79
95% mean confidence interval for instructions %-change: 1.17% 1.46%
Instructions are HURT.

total cycles in shared programs: 363682759 -> 363683977 (<.01%)
cycles in affected programs: 325758 -> 326976 (0.37%)
helped: 44
HURT: 133
helped stats (abs) min: 1 max: 179 x̄: 33.61 x̃: 5
helped stats (rel) min: 0.06% max: 14.21% x̄: 2.47% x̃: 0.29%
HURT stats (abs)   min: 1 max: 157 x̄: 20.28 x̃: 14
HURT stats (rel)   min: 0.07% max: 14.44% x̄: 1.42% x̃: 0.73%
95% mean confidence interval for cycles value: 0.38 13.39
95% mean confidence interval for cycles %-change: -0.06% 0.96%
Inconclusive result (%-change mean confidence interval includes 0).

Sandy Bridge
total instructions in shared programs: 10787433 -> 10787443 (<.01%)
instructions in affected programs: 1842 -> 1852 (0.54%)
helped: 0
HURT: 10
HURT stats (abs)   min: 1 max: 1 x̄: 1.00 x̃: 1
HURT stats (rel)   min: 0.33% max: 1.85% x̄: 0.73% x̃: 0.49%
95% mean confidence interval for instructions value: 1.00 1.00
95% mean confidence interval for instructions %-change: 0.36% 1.10%
Instructions are HURT.

total cycles in shared programs: 153724543 -> 153724563 (<.01%)
cycles in affected programs: 8407 -> 8427 (0.24%)
helped: 1
HURT: 3
helped stats (abs) min: 18 max: 18 x̄: 18.00 x̃: 18
helped stats (rel) min: 0.98% max: 0.98% x̄: 0.98% x̃: 0.98%
HURT stats (abs)   min: 4 max: 18 x̄: 12.67 x̃: 16
HURT stats (rel)   min: 0.21% max: 0.75% x̄: 0.56% x̃: 0.72%
95% mean confidence interval for cycles value: -21.31 31.31
95% mean confidence interval for cycles %-change: -1.11% 1.46%
Inconclusive result (value mean confidence interval includes 0).

No shader-db changes on Iron Lake or GM45.
---

diff --git a/src/compiler/nir/nir_range_analysis.c b/src/compiler/nir/nir_range_analysis.c
index 6fec5fcd7ab..298d9946b56 100644
--- a/src/compiler/nir/nir_range_analysis.c
+++ b/src/compiler/nir/nir_range_analysis.c
@@ -335,6 +335,26 @@ analyze_expression(const nir_alu_instr *instr, unsigned src,
    const struct nir_alu_instr *const alu =
        nir_instr_as_alu(instr->src[src].src.ssa->parent_instr);
 
+   const nir_alu_type use_type = nir_op_infos[instr->op].input_types[src];
+
+   /* Bail if the type of the instruction generating the value does not match
+    * the type the value will be interpreted as.  int/uint/bool can be
+    * reinterpreted trivially.  The most important cases are between float and
+    * non-float.
+    */
+   if (alu->op != nir_op_mov && alu->op != nir_op_bcsel) {
+      const nir_alu_type use_base_type =
+         nir_alu_type_get_base_type(use_type);
+      const nir_alu_type src_base_type =
+         nir_alu_type_get_base_type(nir_op_infos[alu->op].output_type);
+
+      if (use_base_type != src_base_type &&
+          (use_base_type == nir_type_float ||
+           src_base_type == nir_type_float)) {
+         return (struct ssa_result_range){unknown, false};
+      }
+   }
+
    struct hash_entry *he = _mesa_hash_table_search(ht, alu);
    if (he != NULL)
       return unpack_data(he->data);