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ast_ternary_codegen - beware, it's almost a spaghetti... almost...

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Wolfgang (Blub) Bumiller 2012-05-03 13:02:29 +02:00
parent 91bf040f0a
commit 4c9c6ee5bd
1 changed files with 91 additions and 1 deletions
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92
ast.c
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@ -743,6 +743,17 @@ bool ast_ifthen_codegen(ast_ifthen *self, ast_function *func, bool lvalue, ir_va
bool ast_ternary_codegen(ast_ternary *self, ast_function *func, bool lvalue, ir_value **out)
{
ast_expression_codegen *cgen;
ir_value *condval;
ir_value *trueval, *falseval;
ir_instr *phi;
ir_block *cond = func->curblock;
ir_block *ontrue;
ir_block *onfalse;
ir_block *merge;
/* In theory it shouldn't be possible to pass through a node twice, but
* in case we add any kind of optimization pass for the AST itself, it
* may still happen, thus we remember a created ir_value and simply return one
@ -752,5 +763,84 @@ bool ast_ternary_codegen(ast_ternary *self, ast_function *func, bool lvalue, ir_
*out = self->phi_out;
return true;
}
return false;
/* Ternary can never create an lvalue... */
if (lvalue)
return false;
/* In the following, contraty to ast_ifthen, we assume both paths exist. */
/* create on-true block */
ontrue = ir_function_create_block(func->ir_func, ast_function_label(func, "tern_T"));
if (!ontrue)
return false;
/* create on-false block */
onfalse = ir_function_create_block(func->ir_func, ast_function_label(func, "tern_F"));
if (!onfalse)
return false;
merge = ir_function_create_block(func->ir_func, ast_function_label(func, "tern_out"));
if (!merge)
return NULL;
/* generate the condition */
func->curblock = cond;
cgen = self->cond->expression.codegen;
if (!(*cgen)((ast_expression*)(self->cond), func, false, &condval))
return false;
if (!ir_block_create_if(cond, condval, ontrue, onfalse))
return false;
/* on-true path */
/* enter the block */
func->curblock = ontrue;
/* generate */
cgen = self->on_true->expression.codegen;
if (!(*cgen)((ast_expression*)(self->on_true), func, false, &trueval))
return false;
/* jump to merge block */
if (!ir_block_create_jump(ontrue, merge))
return false;
/* on-false path */
/* enter the block */
func->curblock = onfalse;
/* generate */
cgen = self->on_false->expression.codegen;
if (!(*cgen)((ast_expression*)(self->on_false), func, false, &falseval))
return false;
/* jump to merge block */
if (!ir_block_create_jump(ontrue, merge))
return false;
/* Now enter the merge block */
func->curblock = merge;
/* Here, now, we need a PHI node
* but first some sanity checking...
*/
if (trueval->vtype != falseval->vtype) {
/* error("ternary with different types on the two sides"); */
return false;
}
/* create PHI */
phi = ir_block_create_phi(merge, ast_function_label(func, "phi"), trueval->vtype);
if (!phi ||
!ir_phi_add(phi, ontrue, trueval) ||
!ir_phi_add(phi, onfalse, falseval))
{
return false;
}
self->phi_out = ir_phi_value(phi);
*out = self->phi_out;
return true;
}