Mesa (master): glsl: Perform implicit type conversions on function call out parameters.
Paul Berry
stereotype441 at kemper.freedesktop.org
Tue Aug 16 00:25:05 UTC 2011
Module: Mesa
Branch: master
Commit: 67b5a3267d639c31d3ac4073be877ffb0f5637d3
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=67b5a3267d639c31d3ac4073be877ffb0f5637d3
Author: Paul Berry <stereotype441 at gmail.com>
Date: Tue Aug 2 14:34:17 2011 -0700
glsl: Perform implicit type conversions on function call out parameters.
When an out parameter undergoes an implicit type conversion, we need
to store it in a temporary, and then after the call completes, convert
the resulting value. In other words, we convert code like the
following:
void f(out int x);
float value;
f(value);
Into IR that's equivalent to this:
void f(out int x);
float value;
int out_parameter_conversion;
f(out_parameter_conversion);
value = float(out_parameter_conversion);
This transformation needs to happen during ast-to-IR convertion (as
opposed to, say, a lowering pass), because it is invalid IR for formal
and actual parameters to have types that don't match.
Fixes piglit tests
spec/glsl-1.20/compiler/qualifiers/out-conversion-int-to-float.vert and
spec/glsl-1.20/execution/qualifiers/vs-out-conversion-*.shader_test,
and bug 39651.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=39651
Reviewed-by: Chad Versace <chad at chad-versace.us>
---
src/glsl/ast_function.cpp | 76 ++++++++++++++++++++++++++++++++++++++++++---
1 files changed, 71 insertions(+), 5 deletions(-)
diff --git a/src/glsl/ast_function.cpp b/src/glsl/ast_function.cpp
index 5b6ed3b..c49a33d 100644
--- a/src/glsl/ast_function.cpp
+++ b/src/glsl/ast_function.cpp
@@ -134,6 +134,8 @@ match_function_by_name(exec_list *instructions, const char *name,
}
}
+ exec_list post_call_conversions;
+
if (sig != NULL) {
/* Verify that 'out' and 'inout' actual parameters are lvalues. This
* isn't done in ir_function::matching_signature because that function
@@ -141,6 +143,12 @@ match_function_by_name(exec_list *instructions, const char *name,
*
* Also, validate that 'const_in' formal parameters (an extension of our
* IR) correspond to ir_constant actual parameters.
+ *
+ * Also, perform implicit conversion of arguments. Note: to implicitly
+ * convert out parameters, we need to place them in a temporary
+ * variable, and do the conversion after the call takes place. Since we
+ * haven't emitted the call yet, we'll place the post-call conversions
+ * in a temporary exec_list, and emit them later.
*/
exec_list_iterator actual_iter = actual_parameters->iterator();
exec_list_iterator formal_iter = sig->parameters.iterator();
@@ -185,8 +193,63 @@ match_function_by_name(exec_list *instructions, const char *name,
}
if (formal->type->is_numeric() || formal->type->is_boolean()) {
- ir_rvalue *converted = convert_component(actual, formal->type);
- actual->replace_with(converted);
+ switch (formal->mode) {
+ case ir_var_in: {
+ ir_rvalue *converted
+ = convert_component(actual, formal->type);
+ actual->replace_with(converted);
+ break;
+ }
+ case ir_var_out:
+ if (actual->type != formal->type) {
+ /* To convert an out parameter, we need to create a
+ * temporary variable to hold the value before conversion,
+ * and then perform the conversion after the function call
+ * returns.
+ *
+ * This has the effect of transforming code like this:
+ *
+ * void f(out int x);
+ * float value;
+ * f(value);
+ *
+ * Into IR that's equivalent to this:
+ *
+ * void f(out int x);
+ * float value;
+ * int out_parameter_conversion;
+ * f(out_parameter_conversion);
+ * value = float(out_parameter_conversion);
+ */
+ ir_variable *tmp =
+ new(ctx) ir_variable(formal->type,
+ "out_parameter_conversion",
+ ir_var_temporary);
+ instructions->push_tail(tmp);
+ ir_dereference_variable *deref_tmp_1
+ = new(ctx) ir_dereference_variable(tmp);
+ ir_dereference_variable *deref_tmp_2
+ = new(ctx) ir_dereference_variable(tmp);
+ ir_rvalue *converted_tmp
+ = convert_component(deref_tmp_1, actual->type);
+ ir_assignment *assignment
+ = new(ctx) ir_assignment(actual, converted_tmp);
+ post_call_conversions.push_tail(assignment);
+ actual->replace_with(deref_tmp_2);
+ }
+ break;
+ case ir_var_inout:
+ /* Inout parameters should never require conversion, since that
+ * would require an implicit conversion to exist both to and
+ * from the formal parameter type, and there are no
+ * bidirectional implicit conversions.
+ */
+ assert (actual->type == formal->type);
+ break;
+ default:
+ assert (!"Illegal formal parameter mode");
+ break;
+ }
}
actual_iter.next();
@@ -196,8 +259,11 @@ match_function_by_name(exec_list *instructions, const char *name,
/* Always insert the call in the instruction stream, and return a deref
* of its return val if it returns a value, since we don't know if
* the rvalue is going to be assigned to anything or not.
+ *
+ * Also insert any out parameter conversions after the call.
*/
ir_call *call = new(ctx) ir_call(sig, actual_parameters);
+ ir_dereference_variable *deref;
if (!sig->return_type->is_void()) {
/* If the function call is a constant expression, don't
* generate the instructions to call it; just generate an
@@ -214,7 +280,6 @@ match_function_by_name(exec_list *instructions, const char *name,
}
ir_variable *var;
- ir_dereference_variable *deref;
var = new(ctx) ir_variable(sig->return_type,
ralloc_asprintf(ctx, "%s_retval",
@@ -227,11 +292,12 @@ match_function_by_name(exec_list *instructions, const char *name,
instructions->push_tail(assign);
deref = new(ctx) ir_dereference_variable(var);
- return deref;
} else {
instructions->push_tail(call);
- return NULL;
+ deref = NULL;
}
+ instructions->append_list(&post_call_conversions);
+ return deref;
} else {
char *str = prototype_string(NULL, name, actual_parameters);
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