From 0ae9ce0f29ea1973b850a4e6c6cae8606973036e Mon Sep 17 00:00:00 2001 From: Jason Ekstrand Date: Sat, 19 Aug 2017 20:31:03 -0700 Subject: [PATCH] i965/clear: Quantize the depth clear value based on the format In f9fd976e8adba733b08d we changed the clear value to be stored as an isl_color_value. This had the side-effect same clear value check is now happening directly between the f32[0] field of the isl_color_value and ctx->Depth.Clear. This isn't what we want for two reasons. One is that the comparison happens in floating point even for Z16 and Z24 formats. Worse than that, ctx->Depth.Clear is a double so, even for 32-bit float formats, we were comparing as doubles and not floats. This means that the test basically always fails for anything other than 0.0f and 1.0f. This caused a slight performance regression in Lightsmark 2008 because it was using a depth clear value of 0.999 which can't be stored in a 32-bit float so we were doing unneeded resolves. Reviewed-by: Kenneth Graunke Bugzilla: https://bugs.freedesktop.org/101678 Cc: "17.2" --- src/mesa/drivers/dri/i965/brw_clear.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/src/mesa/drivers/dri/i965/brw_clear.c b/src/mesa/drivers/dri/i965/brw_clear.c index 5eb24237927..b7bf03d8e0a 100644 --- a/src/mesa/drivers/dri/i965/brw_clear.c +++ b/src/mesa/drivers/dri/i965/brw_clear.c @@ -159,12 +159,22 @@ brw_fast_clear_depth(struct gl_context *ctx) break; } + /* Quantize the clear value to what can be stored in the actual depth + * buffer. This makes the following check more accurate because it now + * checks if the actual depth bits will match. It also prevents us from + * getting a too-accurate depth value during depth testing or when sampling + * with HiZ enabled. + */ + float clear_value = + mt->format == MESA_FORMAT_Z_FLOAT32 ? ctx->Depth.Clear : + (unsigned)(ctx->Depth.Clear * fb->_DepthMax) / (float)fb->_DepthMax; + const uint32_t num_layers = depth_att->Layered ? depth_irb->layer_count : 1; /* If we're clearing to a new clear value, then we need to resolve any clear * flags out of the HiZ buffer into the real depth buffer. */ - if (mt->fast_clear_color.f32[0] != ctx->Depth.Clear) { + if (mt->fast_clear_color.f32[0] != clear_value) { for (uint32_t level = mt->first_level; level <= mt->last_level; level++) { if (!intel_miptree_level_has_hiz(mt, level)) continue; @@ -201,7 +211,7 @@ brw_fast_clear_depth(struct gl_context *ctx) } } - mt->fast_clear_color.f32[0] = ctx->Depth.Clear; + mt->fast_clear_color.f32[0] = clear_value; } bool need_clear = false; -- 2.30.2