Mesa (glsl-continue-return): glsl: code refactoring for return statements
Brian Paul
brianp at kemper.freedesktop.org
Thu Jun 25 20:12:52 UTC 2009
Module: Mesa
Branch: glsl-continue-return
Commit: 2d09e1084ed09f0b46355eab81739f2332a8d279
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=2d09e1084ed09f0b46355eab81739f2332a8d279
Author: Brian Paul <brianp at vmware.com>
Date: Thu Jun 25 11:32:37 2009 -0600
glsl: code refactoring for return statements
---
src/mesa/shader/slang/slang_codegen.c | 158 ++++++++++++++++++---------------
1 files changed, 88 insertions(+), 70 deletions(-)
diff --git a/src/mesa/shader/slang/slang_codegen.c b/src/mesa/shader/slang/slang_codegen.c
index bb1ae03..0d72f4e 100644
--- a/src/mesa/shader/slang/slang_codegen.c
+++ b/src/mesa/shader/slang/slang_codegen.c
@@ -75,6 +75,11 @@ const GLuint MAX_FOR_LOOP_UNROLL_COMPLEXITY = 256;
static slang_ir_node *
_slang_gen_operation(slang_assemble_ctx * A, slang_operation *oper);
+static void
+slang_substitute(slang_assemble_ctx *A, slang_operation *oper,
+ GLuint substCount, slang_variable **substOld,
+ slang_operation **substNew, GLboolean isLHS);
+
/**
* Retrieves type information about an operation.
@@ -927,6 +932,78 @@ slang_resolve_variable(slang_operation *oper)
/**
+ * Generate code for "return expr;"
+ * We return values from functions by assinging the returned value to
+ * the hidden __retVal variable which is an extra 'out' parameter we add
+ * to the function signature.
+ * This code basically converts "return expr;" into "__retVal = expr; return;"
+ * \return the new AST code.
+ */
+static slang_operation *
+gen_return_expression(slang_assemble_ctx *A, slang_operation *oper)
+{
+ slang_operation *blockOper;
+
+ blockOper = slang_operation_new(1);
+ blockOper->type = SLANG_OPER_BLOCK_NO_NEW_SCOPE;
+ blockOper->locals->outer_scope = oper->locals->outer_scope;
+ slang_operation_add_children(blockOper, 2);
+
+ /* if EmitContReturn:
+ * if (!__returnFlag) {
+ * build: __retVal = expr;
+ * }
+ * otherwise:
+ * build: __retVal = expr;
+ */
+ {
+ slang_operation *assignOper;
+
+ if (A->UseReturnFlag) {
+ slang_operation *ifOper = slang_oper_child(blockOper, 0);
+ ifOper->type = SLANG_OPER_IF;
+ slang_operation_add_children(ifOper, 3);
+ {
+ slang_operation *cond = slang_oper_child(ifOper, 0);
+ cond->type = SLANG_OPER_IDENTIFIER;
+ cond->a_id = slang_atom_pool_atom(A->atoms, "__returnFlag");
+ }
+ {
+ slang_operation *elseOper = slang_oper_child(ifOper, 2);
+ elseOper->type = SLANG_OPER_VOID;
+ }
+ assignOper = slang_oper_child(ifOper, 1);
+ }
+ else {
+ assignOper = slang_oper_child(blockOper, 0);
+ }
+
+ assignOper->type = SLANG_OPER_ASSIGN;
+ slang_operation_add_children(assignOper, 2);
+ {
+ slang_operation *lhs = slang_oper_child(assignOper, 0);
+ lhs->type = SLANG_OPER_IDENTIFIER;
+ lhs->a_id = slang_atom_pool_atom(A->atoms, "__retVal");
+ }
+ {
+ slang_operation *rhs = slang_oper_child(assignOper, 1);
+ slang_operation_copy(rhs, &oper->children[0]);
+ }
+ }
+
+ /* build: return; (with no return value) */
+ {
+ slang_operation *returnOper = slang_oper_child(blockOper, 1);
+ returnOper->type = SLANG_OPER_RETURN; /* return w/ no value */
+ assert(returnOper->num_children == 0);
+ }
+
+ return blockOper;
+}
+
+
+
+/**
* Replace particular variables (SLANG_OPER_IDENTIFIER) with new expressions.
*/
static void
@@ -994,14 +1071,7 @@ slang_substitute(slang_assemble_ctx *A, slang_operation *oper,
/* do return replacement here too */
assert(oper->num_children == 0 || oper->num_children == 1);
if (oper->num_children == 1 && !_slang_is_noop(&oper->children[0])) {
- /* replace:
- * return expr;
- * with:
- * __retVal = expr;
- * return;
- * then do substitutions on the assignment.
- */
- slang_operation *blockOper;
+ slang_operation *newReturn;
/* check if function actually has a return type */
assert(A->CurFunction);
@@ -1010,70 +1080,16 @@ slang_substitute(slang_assemble_ctx *A, slang_operation *oper,
return;
}
- blockOper = slang_operation_new(1);
- blockOper->type = SLANG_OPER_BLOCK_NO_NEW_SCOPE;
- blockOper->locals->outer_scope = oper->locals->outer_scope;
- slang_operation_add_children(blockOper, 2);
-
- /* if EmitContReturn:
- * if (!__returnFlag) {
- * build: __retVal = expr;
- * }
- * otherwise:
- * build: __retVal = expr;
- */
- {
- slang_operation *assignOper;
+ /* generate new 'return' code' */
+ newReturn = gen_return_expression(A, oper);
- if (A->UseReturnFlag) {
- slang_operation *ifOper = slang_oper_child(blockOper, 0);
- ifOper->type = SLANG_OPER_IF;
- slang_operation_add_children(ifOper, 3);
-
- {
- slang_operation *cond = slang_oper_child(ifOper, 0);
- cond->type = SLANG_OPER_IDENTIFIER;
- cond->a_id = slang_atom_pool_atom(A->atoms, "__returnFlag");
- }
- {
- assignOper = slang_oper_child(ifOper, 1);
- }
- {
- slang_operation *elseOper = slang_oper_child(ifOper, 2);
- elseOper->type = SLANG_OPER_VOID;
- }
- }
- else {
- assignOper = slang_oper_child(blockOper, 0);
- }
+ /* do substitutions on the "__retVal = expr" sub-tree */
+ slang_substitute(A, slang_oper_child(newReturn, 0),
+ substCount, substOld, substNew, GL_FALSE);
- assignOper->type = SLANG_OPER_ASSIGN;
- slang_operation_add_children(assignOper, 2);
- {
- slang_operation *lhs = slang_oper_child(assignOper, 0);
- lhs->type = SLANG_OPER_IDENTIFIER;
- lhs->a_id = slang_atom_pool_atom(A->atoms, "__retVal");
- }
- {
- slang_operation *rhs = slang_oper_child(assignOper, 1);
- slang_operation_copy(rhs, &oper->children[0]);
- }
-
- /* do substitutions on the "__retVal = expr" sub-tree */
- slang_substitute(A, assignOper,
- substCount, substOld, substNew, GL_FALSE);
- }
-
- /* build: return; */
- {
- slang_operation *returnOper = slang_oper_child(blockOper, 1);
- returnOper->type = SLANG_OPER_RETURN; /* return w/ no value */
- assert(returnOper->num_children == 0);
- }
-
- /* install new code */
- slang_operation_copy(oper, blockOper);
- slang_operation_destruct(blockOper);
+ /* install new 'return' code */
+ slang_operation_copy(oper, newReturn);
+ slang_operation_destruct(newReturn);
}
else {
/* check if return value was expected */
@@ -4036,6 +4052,8 @@ _slang_gen_return(slang_assemble_ctx * A, slang_operation *oper)
}
#endif
+ /* XXX use the gen_return_expression() function here */
+
assign = slang_operation_new(1);
assign->type = SLANG_OPER_ASSIGN;
assign->num_children = 2;
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