Committed. The label of interest here is "b.0_2" for e.g. x86_64-pc-linux-gnu but "b::1_2" for mmix-knuth-mmixware. The test seems to be of some interest for mmix (hey, gcc open-coded 128-bit integer support behind my back!) so I didn't want to just disable it. I also didn't want to obscure the matching pattern by generalizing it, so instead I added a separate matching pattern.
gcc/testsuite: * gcc.dg/tree-ssa/forwprop-36.c: Adjust for mmix. --- gcc/gcc/testsuite/gcc.dg/tree-ssa/forwprop-36.c.orig Mon Jan 13 22:30:47 2020 +++ gcc/gcc/testsuite/gcc.dg/tree-ssa/forwprop-36.c Sun Jul 26 03:14:43 2020 @@ -21,4 +21,5 @@ main () return 0; } -/* { dg-final { scan-tree-dump "if \\(b.0_\[0-9\]+ != 0\\)" "cddce1" } } */ +/* { dg-final { scan-tree-dump "if \\(b.0_\[0-9\]+ != 0\\)" "cddce1" { target { ! mmix-knuth-mmixware } } } } */ +/* { dg-final { scan-tree-dump "if \\(b::1_\[0-9\]+ != 0\\)" "cddce1" { target { mmix-knuth-mmixware } } } } */