From 8d4f8e7e6a0492fbbafe7faef7232f29e99b1a38 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20=C5=9Alusarz?= Date: Fri, 13 Aug 2021 16:39:09 +0200 Subject: [PATCH] glsl/opt_algebraic: disable invalid optimization MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When operators other than eq and ne are involved we can't really move operands around and negate them because such transformation may change the value of the whole expression. Some examples: For unsigned var: 0 >= 1u + var would eventually become 0xffffffff >= var, which would always evaluate to true, when original expression was true only for var == 0xffffffff. For signed var: 0 >= 1 + var would become -1 >= var, which would evaluate to false for var == 2147483647, when original expression evaluated to true (because signed overflow is defined to wrap around in glsl, 1 + 2147483647 == -2147483648, so 0 >= -2147483648). Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/5226 Fixes: 34ec1a24d61 ("glsl: Optimize (x + y cmp 0) into (x cmp -y).") Signed-off-by: Marcin Ślusarz Reviewed-by: Alyssa Rosenzweig Reviewed-by: Ian Romanick Part-of: (cherry picked from commit 89bc8ff4083029187f099af531e4db0e223c62ca) --- .pick_status.json | 2 +- src/compiler/glsl/opt_algebraic.cpp | 2 -- 2 files changed, 1 insertion(+), 3 deletions(-) diff --git a/.pick_status.json b/.pick_status.json index 8f2b50250f4..06a2ea0dfbd 100644 --- a/.pick_status.json +++ b/.pick_status.json @@ -130,7 +130,7 @@ "description": "glsl/opt_algebraic: disable invalid optimization", "nominated": true, "nomination_type": 1, - "resolution": 0, + "resolution": 1, "main_sha": null, "because_sha": "34ec1a24d61f8b2f6ed58efa9fe7ea8cec917612" }, diff --git a/src/compiler/glsl/opt_algebraic.cpp b/src/compiler/glsl/opt_algebraic.cpp index 7cef4fc6ef9..14d6e13839b 100644 --- a/src/compiler/glsl/opt_algebraic.cpp +++ b/src/compiler/glsl/opt_algebraic.cpp @@ -708,8 +708,6 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir) } break; - case ir_binop_less: - case ir_binop_gequal: case ir_binop_equal: case ir_binop_nequal: for (int add_pos = 0; add_pos < 2; add_pos++) {