On Wed, Apr 15, 2020 at 9:57 AM Christian König <christian.koenig@xxxxxxx> wrote: > > Am 15.04.20 um 09:41 schrieb Jani Nikula: > > On Tue, 14 Apr 2020, Alex Deucher <alexdeucher@xxxxxxxxx> wrote: > >> On Tue, Apr 14, 2020 at 9:05 AM Bernard Zhao <bernard@xxxxxxxx> wrote: > >>> On some processors, the / operate will call the compiler`s div lib, > >>> which is low efficient, We can replace the / operation with shift, > >>> so that we can replace the call of the division library with one > >>> shift assembly instruction. > > This was applied already, and it's not in a driver I look after... but > > to me this feels like something that really should be > > justified. Using >> instead of / for multiples of 2 division mattered 20 > > years ago, I'd be surprised if it still did on modern compilers. > > I have similar worries, especially since we replace the "/ (4 * 2)" with > ">> 3" it's making the code just a bit less readable. > > And that the code runs exactly once while loading the driver and pushing > the firmware into the hardware. So performance is completely irrelevant > here. Yeah, and even in general I'd really want to see proof that such bad compilers exist first. Doing a peephole pass for stuff like this is like undergrad compiler course stuff. Also I'd trust the compiler's call on which is faster much more than humans doing a manual peephole pass. Or am I just massively biased from all the layman following of what kind of our gl/vk/compute compiler people are doing on a daily basis? -Daniel > > Regards, > Christian. > > > > > BR, > > Jani. > > > > > >>> Signed-off-by: Bernard Zhao <bernard@xxxxxxxx> > >> Applied. thanks. > >> > >> Alex > >> > >>> --- > >>> drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c | 4 ++-- > >>> drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c | 4 ++-- > >>> drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c | 4 ++-- > >>> 3 files changed, 6 insertions(+), 6 deletions(-) > >>> > >>> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c > >>> index b205039..66cd078 100644 > >>> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c > >>> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c > >>> @@ -175,10 +175,10 @@ static int gmc_v6_0_mc_load_microcode(struct amdgpu_device *adev) > >>> amdgpu_ucode_print_mc_hdr(&hdr->header); > >>> > >>> adev->gmc.fw_version = le32_to_cpu(hdr->header.ucode_version); > >>> - regs_size = le32_to_cpu(hdr->io_debug_size_bytes) / (4 * 2); > >>> + regs_size = le32_to_cpu(hdr->io_debug_size_bytes) >> 3; > >>> new_io_mc_regs = (const __le32 *) > >>> (adev->gmc.fw->data + le32_to_cpu(hdr->io_debug_array_offset_bytes)); > >>> - ucode_size = le32_to_cpu(hdr->header.ucode_size_bytes) / 4; > >>> + ucode_size = le32_to_cpu(hdr->header.ucode_size_bytes) >> 2; > >>> new_fw_data = (const __le32 *) > >>> (adev->gmc.fw->data + le32_to_cpu(hdr->header.ucode_array_offset_bytes)); > >>> > >>> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c > >>> index 9da9596..ca26d63 100644 > >>> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c > >>> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c > >>> @@ -193,10 +193,10 @@ static int gmc_v7_0_mc_load_microcode(struct amdgpu_device *adev) > >>> amdgpu_ucode_print_mc_hdr(&hdr->header); > >>> > >>> adev->gmc.fw_version = le32_to_cpu(hdr->header.ucode_version); > >>> - regs_size = le32_to_cpu(hdr->io_debug_size_bytes) / (4 * 2); > >>> + regs_size = le32_to_cpu(hdr->io_debug_size_bytes) >> 3; > >>> io_mc_regs = (const __le32 *) > >>> (adev->gmc.fw->data + le32_to_cpu(hdr->io_debug_array_offset_bytes)); > >>> - ucode_size = le32_to_cpu(hdr->header.ucode_size_bytes) / 4; > >>> + ucode_size = le32_to_cpu(hdr->header.ucode_size_bytes) >> 2; > >>> fw_data = (const __le32 *) > >>> (adev->gmc.fw->data + le32_to_cpu(hdr->header.ucode_array_offset_bytes)); > >>> > >>> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c > >>> index 27d83204..295039c 100644 > >>> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c > >>> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c > >>> @@ -318,10 +318,10 @@ static int gmc_v8_0_tonga_mc_load_microcode(struct amdgpu_device *adev) > >>> amdgpu_ucode_print_mc_hdr(&hdr->header); > >>> > >>> adev->gmc.fw_version = le32_to_cpu(hdr->header.ucode_version); > >>> - regs_size = le32_to_cpu(hdr->io_debug_size_bytes) / (4 * 2); > >>> + regs_size = le32_to_cpu(hdr->io_debug_size_bytes) >> 3; > >>> io_mc_regs = (const __le32 *) > >>> (adev->gmc.fw->data + le32_to_cpu(hdr->io_debug_array_offset_bytes)); > >>> - ucode_size = le32_to_cpu(hdr->header.ucode_size_bytes) / 4; > >>> + ucode_size = le32_to_cpu(hdr->header.ucode_size_bytes) >> 2; > >>> fw_data = (const __le32 *) > >>> (adev->gmc.fw->data + le32_to_cpu(hdr->header.ucode_array_offset_bytes)); > >>> > >>> -- > >>> 2.7.4 > >>> > >>> _______________________________________________ > >>> amd-gfx mailing list > >>> amd-gfx@xxxxxxxxxxxxxxxxxxxxx > >>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.freedesktop.org%2Fmailman%2Flistinfo%2Famd-gfx&data=02%7C01%7Cchristian.koenig%40amd.com%7C1e91f7edcfe0473b0d7008d7e11074a8%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637225333103893889&sdata=VDJlEY2%2Bl1SSO8Fw1dYqqPFqQtyHpsxQ0Tm7iVOgJQY%3D&reserved=0 > >> _______________________________________________ > >> dri-devel mailing list > >> dri-devel@xxxxxxxxxxxxxxxxxxxxx > >> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.freedesktop.org%2Fmailman%2Flistinfo%2Fdri-devel&data=02%7C01%7Cchristian.koenig%40amd.com%7C1e91f7edcfe0473b0d7008d7e11074a8%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637225333103893889&sdata=EpqRRbCiksur%2BjMlVQplExuJsmw6UPODhyBOutOVukw%3D&reserved=0 > > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
