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glsl: code refactoring for return statements

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This commit is contained in:
Brian Paul 2009-06-25 11:32:37 -06:00
parent 2ae297c318
commit 0efd25b502
1 changed files with 88 additions and 70 deletions
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158
src/mesa/shader/slang/slang_codegen.c
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@ -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.
@ -926,6 +931,78 @@ 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.
*/
@ -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);
/* generate new 'return' code' */
newReturn = gen_return_expression(A, oper);
/* if EmitContReturn:
* if (!__returnFlag) {
* build: __retVal = expr;
* }
* otherwise:
* build: __retVal = expr;
*/
{
slang_operation *assignOper;
/* do substitutions on the "__retVal = expr" sub-tree */
slang_substitute(A, slang_oper_child(newReturn, 0),
substCount, substOld, substNew, GL_FALSE);
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);
}
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;