https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108357
--- Comment #15 from rguenther at suse dot de <rguenther at suse dot de> --- On Thu, 13 Apr 2023, xry111 at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108357 > > --- Comment #14 from Xi Ruoyao <xry111 at gcc dot gnu.org> --- > (In reply to rguent...@suse.de from comment #13) > > On Thu, 13 Apr 2023, chenglulu at loongson dot cn wrote: > > > > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108357 > > > > > > --- Comment #10 from chenglulu <chenglulu at loongson dot cn> --- > > > (In reply to Xi Ruoyao from comment #5) > > > > The test fails on loongarch64-linux-gnu. foo is kept in > > > > 114t.threadfull1, > > > > but removed in 135t.forwprop3. > > > > > > > > Does this mean something is wrong for LoongArch, or we should simply > > > > check > > > > the tree dump in a later pass (for e.g. 254t.optimized)? > > > > > > If the definition of the macro DEFAULT_SIGNED_CHAR is changed to 0, the > > > test > > > case can pass the test. I guess it is because the definition of > > > DEFAULT_SIGNED_CHAR affects the optimization of the ccp pass, resulting > > > in some > > > blocks that cannot be removed, resulting in the failure of this test case. > > > > Can you check if making b unsigned fixes the test for you? If so > > that's what we should do. > > It works? > > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr108357.c > b/gcc/testsuite/gcc.dg/tree-ssa/pr108357.c > index 44c457b7a97..79cf371ef28 100644 > --- a/gcc/testsuite/gcc.dg/tree-ssa/pr108357.c > +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr108357.c > @@ -1,7 +1,7 @@ > /* { dg-do compile } */ > /* { dg-options "-O2 -fdump-tree-threadfull1" } */ > > -static char b; > +static unsigned char b; > static unsigned c; > void foo(); > short(a)(short d, short e) { return d * e; } > > But I'm still wondering why this is not an issue for x86_64. Yes, that's interesting to see. It does change how b is extended in b ^ 9854 (but for the value zero it doesn't matter).
