[Mesa-dev] [PATCH] radeonsi: disable sinking common instructions down to the end block

[Samuel Pitoiset]

On 03/15/2017 01:59 AM, Matt Arsenault wrote:
>
>> On Mar 14, 2017, at 17:21, Samuel Pitoiset <samuel.pitoiset at gmail.com> wrote:
>>
>> Initially this was a workaround for a bug introduced in LLVM 4.0
>> in the SimplifyCFG pass that caused image instrinsics to disappear
>> (because they were badly sunk). Finally, this is a win because it
>> decreases SGPR spilling and increases the number of waves a bit.
>>
>> Although, shader-db results are good I think we might want to
>> remove it in the future once the issue is fixed. For now, enable
>> it for LLVM >= 4.0.
>>
>> This also fixes a rendering issue with the speedometer in Dirt Rally.
>>
>> More information can be found here https://reviews.llvm.org/D26348.
>>
>> Thanks to Dave Airlie for the patch.
>>
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99484
>> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
>> ---
>>
>> For those interested, here's the full shader-db report:
>>
>> https://hastebin.com/osepehehat.pas
>>
>> src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c | 6 ++++++
>> 1 file changed, 6 insertions(+)
>>
>> diff --git a/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c b/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c
>> index 5c63b732b3..4fb7a126e4 100644
>> --- a/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c
>> +++ b/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c
>> @@ -40,6 +40,7 @@
>> #include <stdio.h>
>> #include <llvm-c/Transforms/IPO.h>
>> #include <llvm-c/Transforms/Scalar.h>
>> +#include <llvm-c/Support.h>
>>
>> /* Data for if/else/endif and bgnloop/endloop control flow structures.
>>  */
>> @@ -124,6 +125,11 @@ static void init_amdgpu_target()
>> 	LLVMInitializeAMDGPUTarget();
>> 	LLVMInitializeAMDGPUTargetMC();
>> 	LLVMInitializeAMDGPUAsmPrinter();
>> +
>> +#if HAVE_LLVM >= 0x0400
>> +	const char *argv[2] = {"mesa", "-simplifycfg-sink-common=false"};
>> +	LLVMParseCommandLineOptions(2, argv, NULL);
>> +#endif
>> }
>
> Probably should have a FIXME that this is a workaround and a link to an open bug to really fix these issues

Okay, I will change it locally.

>
> -Matt
>