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 f9b246d..5afd53d 100644
--- a/src/glsl/nir/nir_algebraic.py
+++ b/src/glsl/nir/nir_algebraic.py
@@ -60,6 +60,7 @@ static const ${val.c_type} ${val.name} = {
{ ${hex(val)} /* ${val.value} */ },
% elif isinstance(val, Variable):
${val.index}, /* ${val.var_name} */
+ ${'true' if val.is_constant else 'false'},
% elif isinstance(val, Expression):
nir_op_${val.opcode},
{ ${', '.join(src.c_ptr for src in val.sources)} },
@@ -109,6 +110,13 @@ class Constant(Value):
class Variable(Value):
def __init__(self, val, name, varset):
Value.__init__(self, name, "variable")
+
+ 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 18e0330..ec89817 100644
--- a/src/glsl/nir/nir_search.c
+++ b/src/glsl/nir/nir_search.c
@@ -78,6 +78,10 @@ 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].src = instr->src[src].src;
state->variables[var->variable].abs = false;
@@ -236,6 +240,8 @@ construct_value(const nir_search_value *value, nir_alu_type
type,
nir_alu_src val;
nir_alu_src_copy(&val, &state->variables[var->variable], mem_ctx);
+ assert(!var->is_constant);
+
return val;
}
diff --git a/src/glsl/nir/nir_search.h b/src/glsl/nir/nir_search.h
index 8ec58b0..18aa28d 100644
--- a/src/glsl/nir/nir_search.h
+++ b/src/glsl/nir/nir_search.h
@@ -47,6 +47,13 @@ typedef struct {
/** The variable index; Must be less than NIR_SEARCH_MAX_VARIABLES */
unsigned variable;
+
+ /** 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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