From 6c5cf8baa10f0bfdf1e61d944f24fdd7947b2a82 Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Tue, 30 Apr 2013 00:58:09 -0700 Subject: [PATCH] glsl: Ignore redundant prototypes after a function's been defined. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Consider the following shader: vec4 f(vec4 v) { return v; } vec4 f(vec4 v); The prototype exactly matches the signature of the earlier definition, so there's absolutely no point in it. However, it doesn't appear to be illegal. The GLSL 4.30 specification offers two relevant quotes: "If a function name is declared twice with the same parameter types, then the return types and all qualifiers must also match, and it is the same function being declared." "User-defined functions can have multiple declarations, but only one definition." In this case the same function was declared twice, and there's only one definition, which fits both pieces of text. There doesn't appear to be any text saying late prototypes are illegal, so presumably it's valid. Unfortunately, it currently triggers an assertion failure: ir_dereference_variable @ specifies undeclared variable `v' @ When we process the second line, we look for an existing exact match so we can enforce the one-definition rule. We then leave sig set to that existing function, and hit sig->replace_parameters(&hir_parameters), unfortunately nuking our existing definition's parameters (which have actual dereferences) with the prototype's bogus unused parameters. Simply bailing out and ignoring such late prototypes is the safest thing to do. Fixes Piglit's late-proto.vert as well as 3DMark/Ice Storm for Android. NOTE: This is a candidate for stable branches. Signed-off-by: Kenneth Graunke Tested-by: Tapani Pälli Reviewed-by: Jordan Justen Reviewed-by: Chad Versace Reviewed-by: Ian Romanick --- src/glsl/ast_to_hir.cpp | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp index 2638411e36a..e595110865b 100644 --- a/src/glsl/ast_to_hir.cpp +++ b/src/glsl/ast_to_hir.cpp @@ -3205,10 +3205,17 @@ ast_function::hir(exec_list *instructions, "match prototype", name); } - if (is_definition && sig->is_defined) { - YYLTYPE loc = this->get_location(); - - _mesa_glsl_error(& loc, state, "function `%s' redefined", name); + if (sig->is_defined) { + if (is_definition) { + YYLTYPE loc = this->get_location(); + _mesa_glsl_error(& loc, state, "function `%s' redefined", name); + } else { + /* We just encountered a prototype that exactly matches a + * function that's already been defined. This is redundant, + * and we should ignore it. + */ + return NULL; + } } } } else { -- 2.30.2