From 67007080b716c7e51039a381f407ababd68230f7 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Mathias=20Fr=C3=B6hlich?= Date: Wed, 25 Jan 2012 17:35:01 +0100 Subject: [PATCH] glsl: Avoid excessive loop unrolling. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Avoid unrollong loops that are either nested loops or where the loop body times the unroll count is huge. The change is far from being perfect but it extends the loop unrolling decision heuristic by some additional safeguard. In particular this cuts down compilation of a shader precomputing atmospheric scattering integral tables containing two nesting levels in a loop from something way beyond some minutes (I never waited for it to finish) to some fractions of a second. This fixes piglit tests glsl-fs-unroll-explosion and glsl-vs-unroll-explosion on r600g. Reviewed-by: Eric Anholt Signed-off-by: Mathias Fröhlich --- src/glsl/loop_unroll.cpp | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/src/glsl/loop_unroll.cpp b/src/glsl/loop_unroll.cpp index 5b84e101477..d0bcaa6703d 100644 --- a/src/glsl/loop_unroll.cpp +++ b/src/glsl/loop_unroll.cpp @@ -56,6 +56,7 @@ loop_unroll_visitor::visit_leave(ir_loop *ir) { loop_variable_state *const ls = this->state->get(ir); int iterations; + unsigned ir_count; /* If we've entered a loop that hasn't been analyzed, something really, * really bad has happened. @@ -78,6 +79,20 @@ loop_unroll_visitor::visit_leave(ir_loop *ir) if (iterations > (int) max_iterations) return visit_continue; + /* Don't try to unroll nested loops and loops with a huge body. + */ + ir_count = 0; + foreach_list(node, &ir->body_instructions) { + ++ir_count; + + /* If the loop body gets to huge, do not unroll. */ + if (5*max_iterations < ir_count*iterations) + return visit_continue; + /* Do not unroll loops with child loop nodes. */ + if (((ir_instruction *) node)->as_loop()) + return visit_continue; + } + if (ls->num_loop_jumps > 1) return visit_continue; else if (ls->num_loop_jumps) { -- 2.30.2