From: Ian Romanick Date: Thu, 13 Sep 2018 00:16:50 +0000 (-0700) Subject: i965/fs: Don't propagate conditional modifiers from integer compares to adds X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=df9dbc03d3df37c10f2d7b73124f8b3fd7a2518f;p=mesa.git i965/fs: Don't propagate conditional modifiers from integer compares to adds No shader-db changes on any Intel platform... which probably explains why no bugs have been bisected to this problem since it landed in Mesa 18.1. :( The commit mentioned below is in 18.2, so 18.1 would need a slightly different fix (due to code refactoring). Signed-off-by: Ian Romanick Fixes: 77f269bb560 "i965/fs: Refactor propagation of conditional modifiers from compares to adds" Reviewed-by: Alejandro Piñeiro (reviewed the original patch) Cc: Matt Turner (reviewed the original patch) --- diff --git a/src/intel/compiler/brw_fs_cmod_propagation.cpp b/src/intel/compiler/brw_fs_cmod_propagation.cpp index 5b74f267359..5fb522f810f 100644 --- a/src/intel/compiler/brw_fs_cmod_propagation.cpp +++ b/src/intel/compiler/brw_fs_cmod_propagation.cpp @@ -211,9 +211,17 @@ opt_cmod_propagation_local(const gen_device_info *devinfo, bblock_t *block) /* A CMP with a second source of zero can match with anything. A CMP * with a second source that is not zero can only match with an ADD * instruction. + * + * Only apply this optimization to float-point sources. It can fail for + * integers. For inputs a = 0x80000000, b = 4, int(0x80000000) < 4, but + * int(0x80000000) - 4 overflows and results in 0x7ffffffc. that's not + * less than zero, so the flags get set differently than for (a < b). */ if (inst->opcode == BRW_OPCODE_CMP && !inst->src[1].is_zero()) { - progress = cmod_propagate_cmp_to_add(devinfo, block, inst) || progress; + if (brw_reg_type_is_floating_point(inst->src[0].type) && + cmod_propagate_cmp_to_add(devinfo, block, inst)) + progress = true; + continue; }