From 482338842db6ad387316b52fbe9602eee56ad082 Mon Sep 17 00:00:00 2001 From: Paul Berry Date: Mon, 1 Aug 2011 13:06:06 -0700 Subject: Revert "glsl: Skip processing the first function's body in do_dead_functions()." opt_dead_functions contained a shortcut to skip processing the first function's body, based on the assumption that IR functions are topologically sorted, with callees always coming before their callers (therefore the first function cannot contain any calls). This assumption turns out not to be true in general. For example, the following code snippet gets translated to IR that violates this assumption: void f(); void g(); void f() { g(); } void g() { ... } In practice, the shortcut didn't cause bugs because of a coincidence of the circumstances in which opt_dead_functions is called: (a) we do inlining right before dead function elimination, and inlining (when successful) eliminates all calls. (b) for user-defined functions, inlining is always successful, because previous optimization passes (during compilation) have reduced them to a form that is eligible for inlining. (c) the function that appears first in the IR can't possibly call a built-in function, because built-in functions are always emitted before the function that calls them. It seems unnecessarily fragile to have opt_dead_functions depend on these coincidences. And the next patch in this series will break (c). So I'm reverting the shortcut. The consequence will be a slight increase in link time for complex shaders. This reverts commit c75427f4c8767e131e5fb3de44fbc9d904cb992d. Reviewed-by: Kenneth Graunke --- src/glsl/opt_dead_functions.cpp | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) (limited to 'src') diff --git a/src/glsl/opt_dead_functions.cpp b/src/glsl/opt_dead_functions.cpp index 7c64c618c0c..51c77e3b947 100644 --- a/src/glsl/opt_dead_functions.cpp +++ b/src/glsl/opt_dead_functions.cpp @@ -50,7 +50,6 @@ public: ir_dead_functions_visitor() { this->mem_ctx = ralloc_context(NULL); - this->seen_another_function_signature = false; } ~ir_dead_functions_visitor() @@ -65,8 +64,6 @@ public: bool (*predicate)(ir_instruction *ir); - bool seen_another_function_signature; - /* List of signature_entry */ exec_list signature_list; void *mem_ctx; @@ -97,13 +94,7 @@ ir_dead_functions_visitor::visit_enter(ir_function_signature *ir) entry->used = true; } - /* If this is the first signature to look at, no need to descend to see - * if it has calls to another function signature. - */ - if (!this->seen_another_function_signature) { - this->seen_another_function_signature = true; - return visit_continue_with_parent; - } + return visit_continue; } -- cgit v1.2.3