On Fri, Feb 5, 2016 at 2:55 PM, Nicolai Hähnle <nhaeh...@gmail.com> wrote:
> On 04.02.2016 13:52, Tom Stellard wrote:
>>
>> On Thu, Feb 04, 2016 at 09:15:26AM +0100, Nicolai Hähnle wrote:
>>>
>>> From: Nicolai Hähnle <nicolai.haeh...@amd.com>
>>>
>>> Set R600_DEBUG=preoptir to dump the LLVM IR before optimization passes,
>>> to allow diagnosing problems caused by optimization passes.
>>>
>>> Note that in order to compile the resulting IR with llc, you will first
>>> have to run at least the mem2reg pass, e.g.
>>>
>>> opt -mem2reg -S < shader.ll | llc -march=amdgcn -mcpu=bonaire
>>>
>>> Signed-off-by: Michel Dänzer <michel.daen...@amd.com> (original patch)
>>> Signed-off-by: Nicolai Hähnle <nicolai.haeh...@amd.com> (w/ debug flag)
>>> ---
>>> Having the option is a good idea, but I prefer to have a separate debug
>>> flag for it so that when you try to analyze bugs in codegen (which in
>>> my experience happens more often) you don't have to worry about
>>> replicating the exact same sequence of optimizations manually via the
>>> command line to reproduce the problem there.
>>>
>>> src/gallium/drivers/radeon/r600_pipe_common.c | 1 +
>>> src/gallium/drivers/radeon/r600_pipe_common.h | 1 +
>>> src/gallium/drivers/radeonsi/si_shader.c | 16 ++++++++++++++--
>>> 3 files changed, 16 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/src/gallium/drivers/radeon/r600_pipe_common.c
>>> b/src/gallium/drivers/radeon/r600_pipe_common.c
>>> index c827dbd..a1432ed 100644
>>> --- a/src/gallium/drivers/radeon/r600_pipe_common.c
>>> +++ b/src/gallium/drivers/radeon/r600_pipe_common.c
>>> @@ -393,6 +393,7 @@ static const struct debug_named_value
>>> common_debug_options[] = {
>>> { "noir", DBG_NO_IR, "Don't print the LLVM IR"},
>>> { "notgsi", DBG_NO_TGSI, "Don't print the TGSI"},
>>> { "noasm", DBG_NO_ASM, "Don't print disassembled shaders"},
>>> + { "preoptir", DBG_PREOPT_IR, "Print the LLVM IR before initial
>>> optimizations" },
>>>
>>> /* features */
>>> { "nodma", DBG_NO_ASYNC_DMA, "Disable asynchronous DMA" },
>>> diff --git a/src/gallium/drivers/radeon/r600_pipe_common.h
>>> b/src/gallium/drivers/radeon/r600_pipe_common.h
>>> index c7e4c44..4e36631 100644
>>> --- a/src/gallium/drivers/radeon/r600_pipe_common.h
>>> +++ b/src/gallium/drivers/radeon/r600_pipe_common.h
>>> @@ -71,6 +71,7 @@
>>> #define DBG_NO_IR (1 << 12)
>>> #define DBG_NO_TGSI (1 << 13)
>>> #define DBG_NO_ASM (1 << 14)
>>> +#define DBG_PREOPT_IR (1 << 15)
>>> /* Bits 21-31 are reserved for the r600g driver. */
>>> /* features */
>>> #define DBG_NO_ASYNC_DMA (1llu << 32)
>>> diff --git a/src/gallium/drivers/radeonsi/si_shader.c
>>> b/src/gallium/drivers/radeonsi/si_shader.c
>>> index 8b524cf..d9ed6b2 100644
>>> --- a/src/gallium/drivers/radeonsi/si_shader.c
>>> +++ b/src/gallium/drivers/radeonsi/si_shader.c
>>> @@ -4092,7 +4092,7 @@ int si_compile_llvm(struct si_screen *sscreen,
>>> if (r600_can_dump_shader(&sscreen->b, processor)) {
>>> fprintf(stderr, "radeonsi: Compiling shader %d\n",
>>> count);
>>>
>>> - if (!(sscreen->b.debug_flags & DBG_NO_IR))
>>> + if (!(sscreen->b.debug_flags & (DBG_NO_IR |
>>> DBG_PREOPT_IR)))
>>> LLVMDumpModule(mod);
>>> }
>>>
>>> @@ -4178,6 +4178,12 @@ static int si_generate_gs_copy_shader(struct
>>> si_screen *sscreen,
>>> si_llvm_export_vs(bld_base, outputs, gsinfo->num_outputs);
>>>
>>> LLVMBuildRetVoid(bld_base->base.gallivm->builder);
>>> +
>>> + /* Dump LLVM IR before any optimization passes */
>>> + if (sscreen->b.debug_flags & DBG_PREOPT_IR &&
>>> + r600_can_dump_shader(&sscreen->b, TGSI_PROCESSOR_GEOMETRY))
>>> + LLVMDumpModule(bld_base->base.gallivm->module);
>>> +
>>> radeon_llvm_finalize_module(&si_shader_ctx->radeon_bld);
>>>
>>> if (dump)
>>> @@ -4385,9 +4391,15 @@ int si_shader_create(struct si_screen *sscreen,
>>> LLVMTargetMachineRef tm,
>>> }
>>>
>>> LLVMBuildRetVoid(bld_base->base.gallivm->builder);
>>> + mod = bld_base->base.gallivm->module;
>>> +
>>> + /* Dump LLVM IR before any optimization passes */
>>> + if (sscreen->b.debug_flags & DBG_PREOPT_IR &&
>>> + r600_can_dump_shader(&sscreen->b, si_shader_ctx.type))
>>> + LLVMDumpModule(mod);
>>> +
>>
>>
>> Is there any reason not to add the dump in radeon_llvm_finalize_module()
>> after PromoteMem2Reg has run? This would make the output readable by llc
>> and then you would only need to add the dump call in one place.
>
>
> In addition to Michel's observation, that's not really possible anyway
> because all the passes are run at once from LLVMRunFunctionPassManager, the
> functions before just set things up.
>
> I did consider doing the dump from radeon_llvm_finalize_module, but the
> function doesn't have (and probably shouldn't have) the information needed
> to make the decision whether to dump or not, so IMO it's cleaner this way.
Alternatively, you can add a radeonsi wrapper function around
radeon_llvm_finalize_module which also does the dumping.
Marek
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