From 7463d5058009d1e9d9d01292f894271a26a062b8 Mon Sep 17 00:00:00 2001 From: Jason Ekstrand Date: Wed, 4 Oct 2017 13:20:52 -0700 Subject: [PATCH] intel/compiler: Don't propagate cmod into integer multiplies No shader-db change on Sky Lake. Reviewed-by: Matt Turner Cc: mesa-stable@lists.freedesktop.org --- src/intel/compiler/brw_fs_cmod_propagation.cpp | 17 +++++++++++++++++ .../compiler/brw_vec4_cmod_propagation.cpp | 17 +++++++++++++++++ 2 files changed, 34 insertions(+) diff --git a/src/intel/compiler/brw_fs_cmod_propagation.cpp b/src/intel/compiler/brw_fs_cmod_propagation.cpp index db63e942b75..4625d69f89e 100644 --- a/src/intel/compiler/brw_fs_cmod_propagation.cpp +++ b/src/intel/compiler/brw_fs_cmod_propagation.cpp @@ -150,6 +150,23 @@ opt_cmod_propagation_local(const gen_device_info *devinfo, bblock_t *block) if (scan_inst->saturate) break; + /* From the Sky Lake PRM, Vol 2a, "Multiply": + * + * "When multiplying integer data types, if one of the sources + * is a DW, the resulting full precision data is stored in + * the accumulator. However, if the destination data type is + * either W or DW, the low bits of the result are written to + * the destination register and the remaining high bits are + * discarded. This results in undefined Overflow and Sign + * flags. Therefore, conditional modifiers and saturation + * (.sat) cannot be used in this case." + * + * We just disallow cmod propagation on all integer multiplies. + */ + if (!brw_reg_type_is_floating_point(scan_inst->dst.type) && + scan_inst->opcode == BRW_OPCODE_MUL) + break; + /* Otherwise, try propagating the conditional. */ enum brw_conditional_mod cond = inst->src[0].negate ? brw_swap_cmod(inst->conditional_mod) diff --git a/src/intel/compiler/brw_vec4_cmod_propagation.cpp b/src/intel/compiler/brw_vec4_cmod_propagation.cpp index 05e65168193..0d72d82a578 100644 --- a/src/intel/compiler/brw_vec4_cmod_propagation.cpp +++ b/src/intel/compiler/brw_vec4_cmod_propagation.cpp @@ -137,6 +137,23 @@ opt_cmod_propagation_local(bblock_t *block) if (scan_inst->saturate) break; + /* From the Sky Lake PRM, Vol 2a, "Multiply": + * + * "When multiplying integer data types, if one of the sources + * is a DW, the resulting full precision data is stored in + * the accumulator. However, if the destination data type is + * either W or DW, the low bits of the result are written to + * the destination register and the remaining high bits are + * discarded. This results in undefined Overflow and Sign + * flags. Therefore, conditional modifiers and saturation + * (.sat) cannot be used in this case. + * + * We just disallow cmod propagation on all integer multiplies. + */ + if (!brw_reg_type_is_floating_point(scan_inst->dst.type) && + scan_inst->opcode == BRW_OPCODE_MUL) + break; + /* Otherwise, try propagating the conditional. */ enum brw_conditional_mod cond = inst->src[0].negate ? brw_swap_cmod(inst->conditional_mod) -- 2.30.2