[Mesa-dev] [PATCH 6/9] glcpp: Skip unnecessary line continuations removal

[Timothy Arceri]

Reviewed-by: Timothy Arceri <tarceri at itsqueeze.com>

On 22/05/17 06:49, Thomas Helland wrote:
> From: Vladislav Egorov <vegorov180 at gmail.com>
> 
> Overwhelming majority of shaders don't use line continuations. In my
> shader-db only shaders from the Talos Principle and Serious Sam used
> them, less than 1% out of all shaders. Optimize for this case, don't
> do any copying if no line continuation was found.
> ---
>   src/compiler/glsl/glcpp/pp.c | 10 ++++++++--
>   1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/src/compiler/glsl/glcpp/pp.c b/src/compiler/glsl/glcpp/pp.c
> index cd86e369b1..50237a87b6 100644
> --- a/src/compiler/glsl/glcpp/pp.c
> +++ b/src/compiler/glsl/glcpp/pp.c
> @@ -117,6 +117,12 @@ remove_line_continuations(glcpp_parser_t *ctx, const char *shader)
>   	int collapsed_newlines = 0;
>   	int separator_len;
>   
> +	backslash = strchr(shader, '\\');
> +
> +	/* No line continuations were found in this shader, our job is done */
> +	if (backslash == NULL)
> +		return (char *) shader;
> +
>   	search_start = shader;
>   
>   	/* Determine what flavor of newlines this shader is using. GLSL
> @@ -158,8 +164,6 @@ remove_line_continuations(glcpp_parser_t *ctx, const char *shader)
>   	separator_len = strlen(newline_separator);
>   
>   	while (true) {
> -		backslash = strchr(search_start, '\\');
> -
>   		/* If we have previously collapsed any line-continuations,
>   		 * then we want to insert additional newlines at the next
>   		 * occurrence of a newline character to avoid changing any
> @@ -207,6 +211,8 @@ remove_line_continuations(glcpp_parser_t *ctx, const char *shader)
>   			shader = skip_newline (backslash + 1);
>   			search_start = shader;
>   		}
> +
> +		backslash = strchr(search_start, '\\');
>   	}
>   
>   	_mesa_string_buffer_append(sb, shader);
>