With Mesa 18.1, commit be973ed21f6e, si_llvm_load_input_vs() changed the number of source 32-bit wide dword components used for fetching vertex attributes into the vertex shader from a constant 4 to a variable num_channels number, depending on input data format, with some special case handling for input data formats like 64-Bit doubles.
In the case of a GL_DOUBLE input data format with one or two components though, e.g, submitted via ... a) glTexCoordPointer(1, GL_DOUBLE, 0, buffer); b) glTexCoordPointer(2, GL_DOUBLE, 0, buffer); ... the input format would be SI_FIX_FETCH_RG_64_FLOAT, but no special case handling was implemented for that case, so in the default path the number of 32-bit dwords would be set to the number of float input components derived from info->input_usage_mask. This ends with corrupted input to the vertex shader, because fetching a 64-bit double from the vbo requires fetching two 32-bit dwords instead of 1, and fetching a two double input requires 4 dword fetches instead of 2, so in these cases the vertex shader receives incomplete/truncated input data: a) float v = gl_MultiTexCoord0.x; -> v.x is corrupted. b) vec2 v = gl_MultiTexCoord0.xy; -> v.x is assigned correctly, but v.y is corrupted. This happens with the standard TGSI IR compiled shaders. Under NIR with R600_DEBUG=nir, we got correct behavior because the current radeonsi nir code always assigns info->input_usage_mask = TGSI_WRITEMASK_XYZW, thereby always fetches 4 dwords regardless of what the shader actually needs. Fix this by properly assigning 2 or 4 dword fetches for one or two component GL_DOUBLE input. Fixes: be973ed21f6e ("radeonsi: load the right number of components for VS inputs and TBOs") Signed-off-by: Mario Kleiner <mario.kleiner...@gmail.com> Cc: mesa-sta...@lists.freedesktop.org Cc: Marek Olšák <marek.ol...@amd.com> --- src/gallium/drivers/radeonsi/si_shader.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c index 190edce..14bb875 100644 --- a/src/gallium/drivers/radeonsi/si_shader.c +++ b/src/gallium/drivers/radeonsi/si_shader.c @@ -561,6 +561,14 @@ void si_llvm_load_input_vs( /* Do multiple loads for special formats. */ switch (fix_fetch) { + case SI_FIX_FETCH_RG_64_FLOAT: + num_fetches = 1; /* 1 2-dword or 4-dword load */ + fetch_stride = 0; + if (util_last_bit(info->input_usage_mask[input_index]) >= 2) + num_channels = 4; /* 2 doubles in 4 dwords */ + else + num_channels = 2; /* 1 double in 2 dwords */ + break; case SI_FIX_FETCH_RGB_64_FLOAT: num_fetches = 3; /* 3 2-dword loads */ fetch_stride = 8; -- 2.7.4 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev