There are some algebraic transformations that we want to do but only if
certain things are constants. For instance, we may want to replace
a * (b + c) with (a * b) + (a * c) as long as a and either b or c is constant.
While this generates more instructions, some of it will get constant
folded. This commit allows you to match an arbitrary constant value by
adding a "#" on the front of a variable name.
---
src/glsl/nir/nir_algebraic.py | 8 ++++++++
src/glsl/nir/nir_search.c | 6 ++++++
src/glsl/nir/nir_search.h | 7 +++++++
3 files changed, 21 insertions(+)
diff --git a/src/glsl/nir/nir_algebraic.py b/src/glsl/nir/nir_algebraic.py
index 5be2842..df3ceb3 100644
--- a/src/glsl/nir/nir_algebraic.py
+++ b/src/glsl/nir/nir_algebraic.py
@@ -62,6 +62,7 @@ static const ${val.c_type} ${val.name} = {
% elif isinstance(val, Variable):
${val.index}, /* ${val.var_name} */
{ ${', '.join(str(s) for s in val.swizzle)} },
+ ${'true' if val.is_constant else 'false'},
% elif isinstance(val, Expression):
nir_op_${val.opcode},
{ ${', '.join(src.c_ptr for src in val.sources)} },
@@ -116,11 +117,18 @@ class Variable(Value):
match = _swizzle_re.match(val)
if match:
+ assert not val.startswith('#')
val = match.group(1)
self.swizzle = ['xyzw'.find(s) for s in match.group(2)]
else:
self.swizzle = range(4)
+ if val.startswith('#'):
+ val = val[1:]
+ self.is_constant = True
+ else:
+ self.is_constant = False
+
self.var_name = val
self.index = varset[val]
self.name = name
diff --git a/src/glsl/nir/nir_search.c b/src/glsl/nir/nir_search.c
index 0d83ff5..6589edb 100644
--- a/src/glsl/nir/nir_search.c
+++ b/src/glsl/nir/nir_search.c
@@ -84,6 +84,10 @@ match_value(const nir_search_value *value, nir_alu_instr
*instr, unsigned src,
return true;
} else {
+ if (var->is_constant &&
+ instr->src[src].src.ssa->parent_instr->type !=
nir_instr_type_load_const)
+ return false;
+
state->variables_seen |= (1 << var->variable);
state->variables[var->variable].ssa = instr->src[src].src.ssa;
@@ -237,6 +241,8 @@ construct_value(const nir_search_value *value, nir_alu_type
type,
const nir_search_variable *var = nir_search_value_as_variable(value);
assert(state->variables_seen & (1 << var->variable));
+ assert(!var->is_constant);
+
nir_alu_src val;
val.src = nir_src_for_ssa(state->variables[var->variable].ssa);
val.abs = false;
diff --git a/src/glsl/nir/nir_search.h b/src/glsl/nir/nir_search.h
index 8b89dd0..902900f 100644
--- a/src/glsl/nir/nir_search.h
+++ b/src/glsl/nir/nir_search.h
@@ -54,6 +54,13 @@ typedef struct {
* searches.
*/
uint8_t swizzle[4];
+
+ /** Indicates that the given variable must be a constant
+ *
+ * This is only alloed in search expressions and indicates that the
+ * given variable is only allowed to match constant values.
+ */
+ bool is_constant;
} nir_search_variable;
typedef struct {
--
2.2.1
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