From: Roland Scheidegger <srol...@vmware.com> r600 already used the clamped versions, but for some reason this was different to eg/cayman. (Note that it has been different since essentially forever, 7 years, since df62338c491f2cace1a48f99de78e83b5edd82fd in particular, which changed this for r600 but not eg (cayman wasn't supported back then, but probably copied this from the eg part later). The commit does not mention any reason why this difference should exist.) This seems a bit unfortunate, since it would be nice to use ieee arithmetic, I have no idea what this could potentially break and no idea if it really makes sense going back to legacy-style rcp/rsq... This however prevents misrenderings in This War of Mine since using ieee muls (ce7a045feeef8cad155f1c9aa07f166e146e3d00), albeit strictly speaking only rcp_clamped is necessary for this. It seems likely the root cause is some x * rcp(y) calculation where both x and y evaluate to 0. Albeit it apparently works with other drivers, not sure what's up with that...
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103544 --- src/gallium/drivers/r600/r600_shader.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/src/gallium/drivers/r600/r600_shader.c b/src/gallium/drivers/r600/r600_shader.c index 6a755bb3fd..62fc4da901 100644 --- a/src/gallium/drivers/r600/r600_shader.c +++ b/src/gallium/drivers/r600/r600_shader.c @@ -9033,8 +9033,12 @@ static const struct r600_shader_tgsi_instruction eg_shader_tgsi_instruction[] = [TGSI_OPCODE_ARL] = { ALU_OP0_NOP, tgsi_eg_arl}, [TGSI_OPCODE_MOV] = { ALU_OP1_MOV, tgsi_op2}, [TGSI_OPCODE_LIT] = { ALU_OP0_NOP, tgsi_lit}, - [TGSI_OPCODE_RCP] = { ALU_OP1_RECIP_IEEE, tgsi_trans_srcx_replicate}, - [TGSI_OPCODE_RSQ] = { ALU_OP1_RECIPSQRT_IEEE, tgsi_rsq}, + /* XXX: + * For state trackers other than OpenGL, we'll want to use + * _RECIP_IEEE/_RECIPSQRT_IEEE instead. + */ + [TGSI_OPCODE_RCP] = { ALU_OP1_RECIP_CLAMPED, tgsi_trans_srcx_replicate}, + [TGSI_OPCODE_RSQ] = { ALU_OP1_RECIPSQRT_CLAMPED, tgsi_rsq}, [TGSI_OPCODE_EXP] = { ALU_OP0_NOP, tgsi_exp}, [TGSI_OPCODE_LOG] = { ALU_OP0_NOP, tgsi_log}, [TGSI_OPCODE_MUL] = { ALU_OP2_MUL_IEEE, tgsi_op2}, @@ -9256,8 +9260,12 @@ static const struct r600_shader_tgsi_instruction cm_shader_tgsi_instruction[] = [TGSI_OPCODE_ARL] = { ALU_OP0_NOP, tgsi_eg_arl}, [TGSI_OPCODE_MOV] = { ALU_OP1_MOV, tgsi_op2}, [TGSI_OPCODE_LIT] = { ALU_OP0_NOP, tgsi_lit}, - [TGSI_OPCODE_RCP] = { ALU_OP1_RECIP_IEEE, cayman_emit_float_instr}, - [TGSI_OPCODE_RSQ] = { ALU_OP1_RECIPSQRT_IEEE, cayman_emit_float_instr}, + /* XXX: + * For state trackers other than OpenGL, we'll want to use + * _RECIP_IEEE/_RECIPSQRT_IEEE instead. + */ + [TGSI_OPCODE_RCP] = { ALU_OP1_RECIP_CLAMPED, cayman_emit_float_instr}, + [TGSI_OPCODE_RSQ] = { ALU_OP1_RECIPSQRT_CLAMPED, cayman_emit_float_instr}, [TGSI_OPCODE_EXP] = { ALU_OP0_NOP, tgsi_exp}, [TGSI_OPCODE_LOG] = { ALU_OP0_NOP, tgsi_log}, [TGSI_OPCODE_MUL] = { ALU_OP2_MUL_IEEE, tgsi_op2}, -- 2.12.3 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
