commit 1411699ba4cdf29eca037c4320543ab8189bad28
author Jiawei Shao <jiawei.shao@intel.com> Mon Mar 31 17:40:39 2025 -0700
committer Dawn LUCI CQ <dawn-scoped@luci-project-accounts.iam.gserviceaccount.com> Mon Mar 31 17:40:39 2025 -0700
tree 5ff2c1b8afdbcca4767bd674f63e89ec73cce605
parent e1e89b51012b8cdd96d9455d0656c012a855370d

Range Analysis: Get loop exit condition from body block

This patch is the third part to implement the computation of the
range on the loop control variables. In this patch we implement the
function `GetBinaryToCompareLoopControlVariableInLoopBody()` to get
the condition to exit the loop in the loop body block if the loop
meets the below requirements (a straightforward for-loop):
- The loop control variable is only used as the parameter of the
  load instruction.
- The first instruction is to load the loop control variable into a
  temporary variable.
- The second instruction is to compare the temporary variable with
  a constant value and save the result to a boolean variable.
- The second instruction cannot be a comparison that will never be
  true (out of range of 32-bit integer).
- The third instruction is an `ifelse` expression that uses the
  boolean variable got in the second instruction as the condition.
- The true block of the above `ifelse` expression doesn't contain
  `exit_loop`.
- The false block of the above `ifelse` expression only contains
  `exit_loop`.

Bug: chromium:348701956
Test: tint_unittests
Change-Id: Ie99911791eb6530e6d081ac9b54c2ec74e1be64c
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/233294
Commit-Queue: Jiawei Shao <jiawei.shao@intel.com>
Reviewed-by: James Price <jrprice@google.com>