From: Neil Roberts Date: Thu, 14 Aug 2014 14:01:39 +0000 (+0100) Subject: i965/blorp_clear: Use memcpy instead of assignment to copy clear value X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=aa9d4f9d1a01fbb829571dac1cf896a8288c7286;p=mesa.git i965/blorp_clear: Use memcpy instead of assignment to copy clear value Similar to the problem described in 2c50212b14da27de4e3, if we copy the clear value through a regular assignment via a floating point value, then if an integer clear value is being used that happens to contain a signalling NaN value then it would get converted to a quiet NaN when stored via the x87 floating-point registers. This would corrupt the integer value. Instead we should use a memcpy to ensure the exact bit representation is preserved. This bug can be triggered on 32-bit builds with optimisations by using an integer clear color with a value like 0x7f817f81. Reviewed-by: Matt Turner --- diff --git a/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp b/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp index ffbcd1a81b9..8db083736ca 100644 --- a/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp +++ b/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp @@ -202,12 +202,7 @@ brw_blorp_clear_params::brw_blorp_clear_params(struct brw_context *brw, y1 = rb->Height - fb->_Ymin; } - float *push_consts = (float *)&wm_push_consts; - - push_consts[0] = ctx->Color.ClearColor.f[0]; - push_consts[1] = ctx->Color.ClearColor.f[1]; - push_consts[2] = ctx->Color.ClearColor.f[2]; - push_consts[3] = ctx->Color.ClearColor.f[3]; + memcpy(&wm_push_consts.dst_x0, ctx->Color.ClearColor.f, sizeof(float) * 4); use_wm_prog = true; @@ -250,7 +245,7 @@ brw_blorp_clear_params::brw_blorp_clear_params(struct brw_context *brw, if (irb->mt->fast_clear_state != INTEL_FAST_CLEAR_STATE_NO_MCS && !partial_clear && wm_prog_key.use_simd16_replicated_data && is_color_fast_clear_compatible(brw, format, &ctx->Color.ClearColor)) { - memset(push_consts, 0xff, 4*sizeof(float)); + memset(&wm_push_consts, 0xff, 4*sizeof(float)); fast_clear_op = GEN7_FAST_CLEAR_OP_FAST_CLEAR; /* Figure out what the clear rectangle needs to be aligned to, and how