Greg McGary <g...@rivosinc.com> 于2024年1月17日周三 06:20写道: > > The sign bit of a sign-extending load cannot be known until runtime, > so don't attempt to simplify it in the combiner. > > 2024-01-11 Greg McGary <g...@rivosinc.com> > > PR rtl-optimization/113010 > * combine.cc (expand_compound_operation): Don't simplify > SIGN_EXTEND of a MEM on WORD_REGISTER_OPERATIONS targets > > * gcc.c-torture/execute/pr113010.c: New test. > --- > gcc/combine.cc | 5 +++++ > gcc/testsuite/gcc.c-torture/execute/pr113010.c | 9 +++++++++ > 2 files changed, 14 insertions(+) > create mode 100644 gcc/testsuite/gcc.c-torture/execute/pr113010.c > > diff --git a/gcc/combine.cc b/gcc/combine.cc > index 812553c091e..ba587184dfc 100644 > --- a/gcc/combine.cc > +++ b/gcc/combine.cc > @@ -7208,6 +7208,11 @@ expand_compound_operation (rtx x) > if (len == 0) > return x; > > + /* Sign-extending loads can never be simplified at compile time. */ > + if (WORD_REGISTER_OPERATIONS && MEM_P (XEXP (x, 0)) > + && load_extend_op (inner_mode) == SIGN_EXTEND) > + return x; > + > break; > > case ZERO_EXTRACT: > diff --git a/gcc/testsuite/gcc.c-torture/execute/pr113010.c > b/gcc/testsuite/gcc.c-torture/execute/pr113010.c > new file mode 100644 > index 00000000000..a95c613c1df > --- /dev/null > +++ b/gcc/testsuite/gcc.c-torture/execute/pr113010.c > @@ -0,0 +1,9 @@ > +int minus_1 = -1; > + > +int > +main () > +{ > + if ((0, 0xfffffffful) >= minus_1)
There is a warning option: -Wsign-compare Warn when a comparison between signed and unsigned values could produce an incorrect result when the signed value is converted to unsigned. > + __builtin_abort (); > + return 0; > +} > -- > 2.34.1 > -- YunQiang Su