From a719d704741ae21d1b12138c863f22286b98a5af Mon Sep 17 00:00:00 2001 From: Brian Paul Date: Fri, 9 Jan 2009 09:59:49 -0700 Subject: [PATCH] glsl: make minimum struct size = 2, not 1 1-component structs such as "struct foo { float x; }" could get placed at any position within a register. This caused some trouble computing the field offset which assumed all struct objects were placed at R.x. It would be unusual to hit this case in normal shaders. (cherry picked from master, commit ca03e881a8d8fa3e36a601238559c20311373633) --- src/mesa/shader/slang/slang_codegen.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/src/mesa/shader/slang/slang_codegen.c b/src/mesa/shader/slang/slang_codegen.c index cc6d71478d6..712f5975dca 100644 --- a/src/mesa/shader/slang/slang_codegen.c +++ b/src/mesa/shader/slang/slang_codegen.c @@ -213,7 +213,14 @@ _slang_sizeof_type_specifier(const slang_type_specifier *spec) break; case SLANG_SPEC_STRUCT: sz = _slang_field_offset(spec, 0); /* special use */ - if (sz > 4) { + if (sz == 1) { + /* 1-float structs are actually troublesome to deal with since they + * might get placed at R.x, R.y, R.z or R.z. Return size=2 to + * ensure the object is placed at R.x + */ + sz = 2; + } + else if (sz > 4) { sz = (sz + 3) & ~0x3; /* round up to multiple of four */ } break; -- 2.30.2