Hello, While reading the function pre_edge_insert () in gcse.c, something didn't make sense to me:
According to the documentation: /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge if it reaches any of the deleted expressions. */ I understand that before inserting an expression on an edge we should check if it reaches a deleted anticipatable occurrence. This also make sense, since we don't want to insert expression on edge if none of the anticipatable occurrences it reaches was deleted for some reason (e.g. all of these occurrences are inside a PARALLEL instructions). But, when we find a deleted anticipatable occurrence we do: /* Insert this expression on this edge if it would reach the deleted occurrence in BB. */ if (!TEST_BIT (inserted[e], j)) This test prevents us from inserting the same expression twice on the same edge, but it doesn't check that this deleted occurrence is actually reached from the current edge. If what I'm saying here is correct, some redundant expression might be inserted. It also seem to me that the "inserted" sbitmap is unnecessary. We could just use "continue" after an insertion instead of using TEST_BIT (inserted[e], j) and SET_BIT (inserted[e], j). Thanks, Leehod.
