[Mesa-dev] [PATCH 2/8] radeonsi: do EarlyCSEMemSSA LLVM pass

[Miklós Máté]

On 05/06/17 18:50, Marek Olšák wrote:
> From: Marek Olšák <marek.olsak at amd.com>
>
> so that LLVM IR looks like CSE has been run on it. It's also recommended
> by the instruction combining pass.
>
> This also fixes:
> - GL45-CTS.arrays_of_arrays_gl.InteractionFunctionCalls2 (crash)
> - piglit/spec/arb_shader_ballot/execution/fs-readFirstInvocation-uint-loop (fail)
>
> The code size decrease is positive, the register usage isn't. There is
> a decrease in VGPR spilling for Tomb Raider, but increase in DiRT Showdown
> and GRID Autosport.
>
> EarlyCSEMemSSA has a -0.01% change in code size compared EarlyCSE.
This needs LLVM 4.0.0, whereas radeonsi officially only needs 3.9.0.

MM
>
> SGPRS: 1935420 -> 1938076 (0.14 %)
> VGPRS: 1645504 -> 1645988 (0.03 %)
> Spilled SGPRs: 2493 -> 2651 (6.34 %)
> Spilled VGPRs: 107 -> 115 (7.48 %)
> Private memory VGPRs: 1332 -> 1332 (0.00 %)
> Scratch size: 1512 -> 1516 (0.26 %) dwords per thread
> Code Size: 61981592 -> 61890012 (-0.15 %) bytes
> Max Waves: 371847 -> 371798 (-0.01 %)
> ---
>   src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c b/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c
> index 1f8e913..802e2b9 100644
> --- a/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c
> +++ b/src/gallium/drivers/radeonsi/si_shader_tgsi_setup.c
> @@ -1444,20 +1444,22 @@ void si_llvm_optimize_module(struct si_shader_context *ctx)
>   	LLVMAddAlwaysInlinerPass(gallivm->passmgr);
>   
>   	/* This pass should eliminate all the load and store instructions */
>   	LLVMAddPromoteMemoryToRegisterPass(gallivm->passmgr);
>   
>   	/* Add some optimization passes */
>   	LLVMAddScalarReplAggregatesPass(gallivm->passmgr);
>   	LLVMAddLICMPass(gallivm->passmgr);
>   	LLVMAddAggressiveDCEPass(gallivm->passmgr);
>   	LLVMAddCFGSimplificationPass(gallivm->passmgr);
> +	/* This is recommended by the instruction combining pass. */
> +	LLVMAddEarlyCSEMemSSAPass(gallivm->passmgr);
>   	LLVMAddInstructionCombiningPass(gallivm->passmgr);
>   
>   	/* Run the pass */
>   	LLVMRunPassManager(gallivm->passmgr, ctx->gallivm.module);
>   
>   	LLVMDisposeBuilder(gallivm->builder);
>   	LLVMDisposePassManager(gallivm->passmgr);
>   	gallivm_dispose_target_library_info(target_library_info);
>   }
>