Generate a global variable for the return value and replace return
statements with assignments to this variable.
Add a list of return statements to semantic::Function.
Bug: tint:509
Change-Id: I6bc08fcac7858b48f0eff62199d5011665284220
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/44804
Commit-Queue: James Price <jrprice@google.com>
Auto-Submit: James Price <jrprice@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>