I don't have a server handy at the moment but what you are looking for is in the REPORTSERVER.DBO.CATALOG
This has the RDL XML (Report Definitions) which you can query. To get the raw XML your query will look like:
, CONVERT(NVARCHAR(MAX),CONVERT(XML,CONVERT(VARBINARY(MAX),C.CONTENT))) AS REPORTXML
FROM REPORTSERVER.DBO.CATALOG C
WHERE C.CONTENT IS NOT NULL
AND C.TYPE = 2
–AND C.NAME LIKE ‘%REPORT_NAME%’
AND CONVERT(NVARCHAR(MAX),CONVERT(XML,CONVERT(VARBINARY(MAX),C.CONTENT))) LIKE ‘%DESIRED_STRING%’
Note this site. The stored procs are under the "datasets" - the datasets hold either ad-hoc SQL or the procs.
"I cant stress enough the importance of switching from a sequential files mindset to set-based thinking. After you make the switch, you can spend your time tuning and optimizing your queries instead of maintaining lengthy, poor-performing code."
-- Itzik Ben-Gan 2001