From a29117041d5a56167cf3500459f1e52ed0f026e1 Mon Sep 17 00:00:00 2001 From: Hans-Peter Nilsson Date: Sun, 9 Aug 2020 02:05:10 +0200 Subject: [PATCH] gcc.dg/pr30957-1.c: xfail for mmix. IV (loop2_unroll) doesn't like the mmix port. The feelings are mutual. For mmix, gcc.dg/pr30957-1.c fails (runtime and rtl-scan) for these reasons: - IV doesn't handle the zero-extension-by-shift sequences generated by middle-end (expr.c:convert_mode_scalar) in the absence of zero-extend patterns in a port. - (when adding such patterns) IV doesn't understand the subreg constructs generated by middle-end in the absence of addsi3 and compare/branch in SImode (int). - (when hacking pr30957-1.c to iterate using a register-mode type) IV doesn't understand the admittedly weird SFmode operations (performing in DFmode, then truncating, for lack of SFmode operations, but presence of truncdfsf2 and float_extendsfdf2) in order to perform the "Expanding Accumulator" optimization. When also editing the type in the test to be double instead of float, the test passes. While at least the last point seems like a valid reason to just skip the test for mmix, it also seems possible that IV (and maybe convert_mode_scalar by e.g. adding REG_EQUIV notes) be improved to be both smarter and dumber to actually make the test pass, so I think it's better to use xfail. Smarter: understanding zero-extend- by-shift and subregged operations better, and "seeing" the accumulation through the DF/SFmode truncations and expansions. Dumber: ignoring the cost; unrolling the several operations per SFmode add anyway. I'm considering adding a variant of this test with "double" and "__SIZE_TYPE__" iteration types, as that passes for mmix as-is. Maybe as a mmix-specific test; the world has suffered enough from the questionable gcc.dg/pr30957-1.c (see the test and its history). gcc/testsuite: * gcc.dg/pr30957-1.c: xfail for mmix. --- gcc/testsuite/gcc.dg/pr30957-1.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/gcc/testsuite/gcc.dg/pr30957-1.c b/gcc/testsuite/gcc.dg/pr30957-1.c index 6a0ed2045c1..564410913ab 100644 --- a/gcc/testsuite/gcc.dg/pr30957-1.c +++ b/gcc/testsuite/gcc.dg/pr30957-1.c @@ -1,4 +1,4 @@ -/* { dg-do run } */ +/* { dg-do run { xfail { mmix-*-* } } } */ /* We don't (and don't want to) perform this optimisation on soft-float targets, where each addition is a library call. / /* { dg-require-effective-target hard_float } */ @@ -33,4 +33,4 @@ main () exit (0); } -/* { dg-final { scan-rtl-dump "Expanding Accumulator" "loop2_unroll" } } */ +/* { dg-final { scan-rtl-dump "Expanding Accumulator" "loop2_unroll" { xfail mmix-*-* } } } */ -- 2.30.2