On 10/28/19 2:29 PM, Martin Sebor wrote: > A recent enhancement to take advantage of non-constant strlen > results constrained to a known range interacts badly with > the nul-over-nul optimization. The optimization eliminates > nul stores that overwrite the exiting terminating nul of > the destination string. This interaction causes the nul > store to be eliminated in subset of cases when it shouldn't > be. > > The attached patch fixes the bug by avoiding the optimization > for such destinations. It also adjusts the comment that > describes the function with the bug to make its return value > clearer. > > Tested on x86_64-linux. > > Martin > > gcc-92226.diff > > PR tree-optimization/92226 - live nul char store to array eliminated > > gcc/testsuite/ChangeLog: > > PR tree-optimization/92226 > * gcc.dg/strlenopt-88.c: New test. > > gcc/ChangeLog: > > PR tree-optimization/92226 > * tree-ssa-strlen.c (compare_nonzero_chars): Return -1 also when > the offset is in the open range outlined by SI's length. >
OK jeff
