[Mesa-dev] [PATCH] ac/nir: Use an array instead of hashtable for SSA defs.

[Timothy Arceri]

On 10/04/18 17:33, Bas Nieuwenhuizen wrote:
> Saves about 2% of compile time for F1 2017, as well as reduce code
> size of an optimized libvulkan_radeon.so by about 1 KiB.
> 
> This still keeps the hashtable, as we also stored blocks in there.
> ---
>   src/amd/common/ac_nir_to_llvm.c | 22 +++++++++++++---------
>   1 file changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
> index 053c19808f..7c2bd5c0cc 100644
> --- a/src/amd/common/ac_nir_to_llvm.c
> +++ b/src/amd/common/ac_nir_to_llvm.c
> @@ -38,6 +38,8 @@ struct ac_nir_context {
>   
>   	gl_shader_stage stage;
>   
> +	LLVMValueRef *ssa_defs;
> +
>   	struct hash_table *defs;
>   	struct hash_table *phis;
>   	struct hash_table *vars;
> @@ -87,8 +89,7 @@ static LLVMTypeRef get_def_type(struct ac_nir_context *ctx,
>   static LLVMValueRef get_src(struct ac_nir_context *nir, nir_src src)
>   {
>   	assert(src.is_ssa);
> -	struct hash_entry *entry = _mesa_hash_table_search(nir->defs, src.ssa);
> -	return (LLVMValueRef)entry->data;
> +	return nir->ssa_defs[src.ssa->index];
>   }
>   
>   static LLVMValueRef
> @@ -1028,8 +1029,7 @@ static void visit_alu(struct ac_nir_context *ctx, const nir_alu_instr *instr)
>   	if (result) {
>   		assert(instr->dest.dest.is_ssa);
>   		result = ac_to_integer(&ctx->ac, result);
> -		_mesa_hash_table_insert(ctx->defs, &instr->dest.dest.ssa,
> -		                        result);
> +		ctx->ssa_defs[instr->dest.dest.ssa.index] = result;
>   	}
>   }
>   
> @@ -1062,7 +1062,7 @@ static void visit_load_const(struct ac_nir_context *ctx,
>   	} else
>   		value = values[0];
>   
> -	_mesa_hash_table_insert(ctx->defs, &instr->def, value);
> +	ctx->ssa_defs[instr->def.index] = value;
>   }
>   
>   static LLVMValueRef
> @@ -3095,7 +3095,7 @@ static void visit_intrinsic(struct ac_nir_context *ctx,
>   		break;
>   	}
>   	if (result) {
> -		_mesa_hash_table_insert(ctx->defs, &instr->dest.ssa, result);
> +		ctx->ssa_defs[instr->dest.ssa.index] = result;
>   	}
>   }
>   
> @@ -3596,7 +3596,7 @@ write_result:
>   	if (result) {
>   		assert(instr->dest.is_ssa);
>   		result = ac_to_integer(&ctx->ac, result);
> -		_mesa_hash_table_insert(ctx->defs, &instr->dest.ssa, result);
> +		ctx->ssa_defs[instr->dest.ssa.index] = result;
>   	}
>   }
>   
> @@ -3606,7 +3606,7 @@ static void visit_phi(struct ac_nir_context *ctx, nir_phi_instr *instr)
>   	LLVMTypeRef type = get_def_type(ctx, &instr->dest.ssa);
>   	LLVMValueRef result = LLVMBuildPhi(ctx->ac.builder, type, "");
>   
> -	_mesa_hash_table_insert(ctx->defs, &instr->dest.ssa, result);
> +	ctx->ssa_defs[instr->dest.ssa.index] = result;
>   	_mesa_hash_table_insert(ctx->phis, instr, result);
>   }
>   
> @@ -3644,7 +3644,7 @@ static void visit_ssa_undef(struct ac_nir_context *ctx,
>   	else {
>   		undef = LLVMGetUndef(LLVMVectorType(type, num_components));
>   	}
> -	_mesa_hash_table_insert(ctx->defs, &instr->def, undef);
> +	ctx->ssa_defs[instr->def.index] = undef;
>   }
>   
>   static void visit_jump(struct ac_llvm_context *ctx,
> @@ -3927,6 +3927,9 @@ void ac_nir_translate(struct ac_llvm_context *ac, struct ac_shader_abi *abi,
>   
>   	func = (struct nir_function *)exec_list_get_head(&nir->functions);
>   
> +	nir_index_ssa_defs(func->impl);
> +	ctx.ssa_defs = calloc(func->impl->ssa_alloc, sizeof(LLVMValueRef));

You don't seem to allocate enough memory here?