This patch was created by Bihn Pham during his internship at AMD. This patch fixes a very significant performance bug when using the O3 CPU model and Ruby. The issue was Ruby returned false when it received a request to the same address that already has an outstanding request or when the memory is blocked. As a result, O3 unnecessary squashed the pipeline and re-executed instructions. This fix merges readRequestTable and writeRequestTable in Sequencer into a single request table that keeps track of all requests and allows multiple outstanding requests to the same address. This prevents O3 from squashing the pipeline. Change-Id: If934d57b4736861e342de0ab18be4feec464273d Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21219 Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com> Maintainer: Anthony Gutierrez <anthony.gutierrez@amd.com> Tested-by: kokoro <noreply+kokoro@google.com>