From: Roland Scheidegger <srol...@vmware.com> The docs are not very concise in what this really does, however both Alex Deucher and Nicolai Hähnle suggested this only really affects instructions using the CLAMP output modifier, and I've confirmed that with the newly changed piglit isinf_and_isnan test. So, with this bit set, if an instruction has the CLAMP modifier bit (which clamps to [0,1]) set, then NaNs will be converted to zero, otherwise the result will be NaN. D3D10 would require this, glsl doesn't have modifiers (with mesa clamp(x,0,1) would get converted to such a modifier) coupled with a whatever-floats-your-boat specified NaN behavior, but the clamp behavior should probably always be used (this also matches what a decomposition into min(1.0, max(x, 0.0)) would do, if min/max also adhere to the ieee spec of picking the non-nan result). Some apps may in fact rely on this, as this prevents misrenderings in This War of Mine since using ieee muls (ce7a045feeef8cad155f1c9aa07f166e146e3d00), without having to use clamped rcp opcode, which would also fix this bug there. radeonsi also seems to set this bit nowadays if I see that righ (albeit the llvm amdgpu code comment now says "Make clamp modifier on NaN input returns 0" instead of "Do not clamp NAN to 0" since it was changed, which also looks a bit misleading).
v2: set it in all shader stages. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103544 --- src/gallium/drivers/r600/evergreen_state.c | 6 ++++++ src/gallium/drivers/r600/r600_state.c | 9 +++++++++ 2 files changed, 15 insertions(+) diff --git a/src/gallium/drivers/r600/evergreen_state.c b/src/gallium/drivers/r600/evergreen_state.c index 96eb35a981..ef323bf4f6 100644 --- a/src/gallium/drivers/r600/evergreen_state.c +++ b/src/gallium/drivers/r600/evergreen_state.c @@ -3235,6 +3235,7 @@ void evergreen_update_ps_state(struct pipe_context *ctx, struct r600_pipe_shader r600_store_value(cb, /* R_028844_SQ_PGM_RESOURCES_PS */ S_028844_NUM_GPRS(rshader->bc.ngpr) | S_028844_PRIME_CACHE_ON_DRAW(1) | + S_028844_DX10_CLAMP(1) | S_028844_STACK_SIZE(rshader->bc.nstack)); /* After that, the NOP relocation packet must be emitted (shader->bo, RADEON_USAGE_READ). */ @@ -3255,6 +3256,7 @@ void evergreen_update_es_state(struct pipe_context *ctx, struct r600_pipe_shader r600_store_context_reg(cb, R_028890_SQ_PGM_RESOURCES_ES, S_028890_NUM_GPRS(rshader->bc.ngpr) | + S_028890_DX10_CLAMP(1) | S_028890_STACK_SIZE(rshader->bc.nstack)); r600_store_context_reg(cb, R_02888C_SQ_PGM_START_ES, shader->bo->gpu_address >> 8); @@ -3317,6 +3319,7 @@ void evergreen_update_gs_state(struct pipe_context *ctx, struct r600_pipe_shader r600_store_context_reg(cb, R_028878_SQ_PGM_RESOURCES_GS, S_028878_NUM_GPRS(rshader->bc.ngpr) | + S_028878_DX10_CLAMP(1) | S_028878_STACK_SIZE(rshader->bc.nstack)); r600_store_context_reg(cb, R_028874_SQ_PGM_START_GS, shader->bo->gpu_address >> 8); @@ -3357,6 +3360,7 @@ void evergreen_update_vs_state(struct pipe_context *ctx, struct r600_pipe_shader S_0286C4_VS_EXPORT_COUNT(nparams - 1)); r600_store_context_reg(cb, R_028860_SQ_PGM_RESOURCES_VS, S_028860_NUM_GPRS(rshader->bc.ngpr) | + S_028860_DX10_CLAMP(1) | S_028860_STACK_SIZE(rshader->bc.nstack)); if (rshader->vs_position_window_space) { r600_store_context_reg(cb, R_028818_PA_CL_VTE_CNTL, @@ -3391,6 +3395,7 @@ void evergreen_update_hs_state(struct pipe_context *ctx, struct r600_pipe_shader r600_init_command_buffer(cb, 32); r600_store_context_reg(cb, R_0288BC_SQ_PGM_RESOURCES_HS, S_0288BC_NUM_GPRS(rshader->bc.ngpr) | + S_0288BC_DX10_CLAMP(1) | S_0288BC_STACK_SIZE(rshader->bc.nstack)); r600_store_context_reg(cb, R_0288B8_SQ_PGM_START_HS, shader->bo->gpu_address >> 8); @@ -3404,6 +3409,7 @@ void evergreen_update_ls_state(struct pipe_context *ctx, struct r600_pipe_shader r600_init_command_buffer(cb, 32); r600_store_context_reg(cb, R_0288D4_SQ_PGM_RESOURCES_LS, S_0288D4_NUM_GPRS(rshader->bc.ngpr) | + S_0288D4_DX10_CLAMP(1) | S_0288D4_STACK_SIZE(rshader->bc.nstack)); r600_store_context_reg(cb, R_0288D0_SQ_PGM_START_LS, shader->bo->gpu_address >> 8); diff --git a/src/gallium/drivers/r600/r600_state.c b/src/gallium/drivers/r600/r600_state.c index c21e8dabb1..db3d6db70b 100644 --- a/src/gallium/drivers/r600/r600_state.c +++ b/src/gallium/drivers/r600/r600_state.c @@ -2548,6 +2548,12 @@ void r600_update_ps_state(struct pipe_context *ctx, struct r600_pipe_shader *sha r600_store_context_reg_seq(cb, R_028850_SQ_PGM_RESOURCES_PS, 2); r600_store_value(cb, /* R_028850_SQ_PGM_RESOURCES_PS*/ S_028850_NUM_GPRS(rshader->bc.ngpr) | + /* + * docs are misleading about the dx10_clamp bit. This only affects + * instructions using CLAMP dst modifier, in which case they will + * return 0 with this set for a NaN (otherwise NaN). + */ + S_028850_DX10_CLAMP(1) | S_028850_STACK_SIZE(rshader->bc.nstack) | S_028850_UNCACHED_FIRST_INST(ufi)); r600_store_value(cb, exports_ps); /* R_028854_SQ_PGM_EXPORTS_PS */ @@ -2597,6 +2603,7 @@ void r600_update_vs_state(struct pipe_context *ctx, struct r600_pipe_shader *sha S_0286C4_VS_EXPORT_COUNT(nparams - 1)); r600_store_context_reg(cb, R_028868_SQ_PGM_RESOURCES_VS, S_028868_NUM_GPRS(rshader->bc.ngpr) | + S_028868_DX10_CLAMP(1) | S_028868_STACK_SIZE(rshader->bc.nstack)); if (rshader->vs_position_window_space) { r600_store_context_reg(cb, R_028818_PA_CL_VTE_CNTL, @@ -2681,6 +2688,7 @@ void r600_update_gs_state(struct pipe_context *ctx, struct r600_pipe_shader *sha r600_store_context_reg(cb, R_02887C_SQ_PGM_RESOURCES_GS, S_02887C_NUM_GPRS(rshader->bc.ngpr) | + S_02887C_DX10_CLAMP(1) | S_02887C_STACK_SIZE(rshader->bc.nstack)); r600_store_context_reg(cb, R_02886C_SQ_PGM_START_GS, 0); /* After that, the NOP relocation packet must be emitted (shader->bo, RADEON_USAGE_READ). */ @@ -2695,6 +2703,7 @@ void r600_update_es_state(struct pipe_context *ctx, struct r600_pipe_shader *sha r600_store_context_reg(cb, R_028890_SQ_PGM_RESOURCES_ES, S_028890_NUM_GPRS(rshader->bc.ngpr) | + S_028890_DX10_CLAMP(1) | S_028890_STACK_SIZE(rshader->bc.nstack)); r600_store_context_reg(cb, R_028880_SQ_PGM_START_ES, 0); /* After that, the NOP relocation packet must be emitted (shader->bo, RADEON_USAGE_READ). */ -- 2.12.3 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev