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authorEric Anholt <[email protected]>2010-07-29 13:29:17 -0700
committerEric Anholt <[email protected]>2010-07-29 15:19:44 -0700
commita62ef12ef242ecd48887df2aa2052d2ecb0979f7 (patch)
tree7d01aa3d1d9137f591ee1a412fdfb2a5b4a9b266 /src/glsl
parent18964618a14996fff7ab5a5db75c85cd64865ef4 (diff)
glsl2: Make sure functions end with a return before doing ir_if_return.
This catches a few remaining functions that weren't getting inlined, generally operating on global or out variables and using an early return to skip work when possible. Fixes for i965: glsl1-function with early return (3)
Diffstat (limited to 'src/glsl')
-rw-r--r--src/glsl/ir_if_return.cpp62
1 files changed, 61 insertions, 1 deletions
diff --git a/src/glsl/ir_if_return.cpp b/src/glsl/ir_if_return.cpp
index 4d59e707869..293f7aa628d 100644
--- a/src/glsl/ir_if_return.cpp
+++ b/src/glsl/ir_if_return.cpp
@@ -24,13 +24,16 @@
/**
* \file ir_if_return.cpp
*
- * This pass tries to normalize functions to always return from one place.
+ * This pass tries to normalize functions to always return from one
+ * place by moving around blocks of code in if statements.
*
* This helps on hardware with no branching support, and may even be a
* useful transform on hardware supporting control flow by turning
* masked returns into normal returns.
*/
+#include <string.h>
+#include "glsl_types.h"
#include "ir.h"
class ir_if_return_visitor : public ir_hierarchical_visitor {
@@ -40,6 +43,7 @@ public:
this->progress = false;
}
+ ir_visitor_status visit_enter(ir_function_signature *);
ir_visitor_status visit_enter(ir_if *);
void move_outer_block_inside(ir_instruction *ir,
@@ -138,6 +142,62 @@ ir_if_return_visitor::move_outer_block_inside(ir_instruction *ir,
}
}
+/* Normalize a function to always have a return statement at the end.
+ *
+ * This avoids the ir_if handler needing to know whether it is at the
+ * top level of the function to know if there's an implicit return at
+ * the end of the outer block.
+ */
+ir_visitor_status
+ir_if_return_visitor::visit_enter(ir_function_signature *ir)
+{
+ ir_return *ret;
+
+ if (!ir->is_defined)
+ return visit_continue_with_parent;
+ if (strcmp(ir->function_name(), "main") == 0)
+ return visit_continue_with_parent;
+
+ ret = find_return_in_block(&ir->body);
+
+ if (ret) {
+ truncate_after_instruction(ret);
+ } else {
+ if (ir->return_type->is_void()) {
+ ir->body.push_tail(new(ir) ir_return(NULL));
+ } else {
+ /* Probably, if we've got a function with a return value
+ * hitting this point, it's something like:
+ *
+ * float reduce_below_half(float val)
+ * {
+ * while () {
+ * if (val >= 0.5)
+ * val /= 2.0;
+ * else
+ * return val;
+ * }
+ * }
+ *
+ * So we gain a junk return statement of an undefined value
+ * at the end that never gets executed. However, a backend
+ * using this pass is probably desperate to get rid of
+ * function calls, so go ahead and do it for their sake in
+ * case it fixes apps.
+ */
+ ir_variable *undef = new(ir) ir_variable(ir->return_type,
+ "if_return_undef",
+ ir_var_temporary);
+ ir->body.push_tail(undef);
+
+ ir_dereference_variable *deref = new(ir) ir_dereference_variable(undef);
+ ir->body.push_tail(new(ir) ir_return(deref));
+ }
+ }
+
+ return visit_continue;
+}
+
ir_visitor_status
ir_if_return_visitor::visit_enter(ir_if *ir)
{