[Mesa-dev] [PATCH 1/3] nir: add fceil lowering

[Jonathan Marek]

lowers ceil(x) as -floor(-x)

Signed-off-by: Jonathan Marek <jonathan at marek.ca>
---
 src/compiler/nir/nir.h                | 3 +++
 src/compiler/nir/nir_opt_algebraic.py | 1 +
 2 files changed, 4 insertions(+)

diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index dc3c729dee..f9b32a5daf 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -2086,6 +2086,9 @@ typedef struct nir_shader_compiler_options {
    /** lowers ffract to fsub+ffloor: */
    bool lower_ffract;
 
+   /** lowers fceil to fneg+ffloor+fneg: */
+   bool lower_fceil;
+
    bool lower_ldexp;
 
    bool lower_pack_half_2x16;
diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 8b24daddfd..8f4df891b8 100644
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -124,6 +124,7 @@ optimizations = [
    (('flrp at 32', a, b, c), ('fadd', ('fmul', c, ('fsub', b, a)), a), 'options->lower_flrp32'),
    (('flrp at 64', a, b, c), ('fadd', ('fmul', c, ('fsub', b, a)), a), 'options->lower_flrp64'),
    (('ffract', a), ('fsub', a, ('ffloor', a)), 'options->lower_ffract'),
+   (('fceil', a), ('fneg', ('ffloor', ('fneg', a))), 'options->lower_fceil'),
    (('~fadd', ('fmul', a, ('fadd', 1.0, ('fneg', ('b2f', c)))), ('fmul', b, ('b2f', c))), ('bcsel', c, b, a), 'options->lower_flrp32'),
    (('~fadd at 32', ('fmul', a, ('fadd', 1.0, ('fneg',         c ))), ('fmul', b,         c )), ('flrp', a, b, c), '!options->lower_flrp32'),
    (('~fadd at 64', ('fmul', a, ('fadd', 1.0, ('fneg',         c ))), ('fmul', b,         c )), ('flrp', a, b, c), '!options->lower_flrp64'),
-- 
2.17.1