On Sun, Aug 16, 2026 at 4:11 AM Andrea Pinski <[email protected]> wrote: > > This adds the rest of the simple comparisons to combine_comparisons. > This should be make it easier to support a&~b for phiopt and ifcombine. > Since `a > b` for booleans is `a & !b`. > > Bootstrapped and tested on x86_64-linux-gnu.
OK, but ... > PR tree-optimization/117193 > > gcc/ChangeLog: > > * fold-const.cc (combine_comparisons): Add support > for LT, GT, LE, and GE. > * match.pd (`(a CMP0 b) OP (a OP1 b)`): Change to use > simple_comparison > instead of eq/ne. > > gcc/testsuite/ChangeLog: > > * gcc.dg/tree-ssa/cmple-1.c: New test. > > Signed-off-by: Andrea Pinski <[email protected]> > --- > gcc/fold-const.cc | 20 +++++++++ > gcc/match.pd | 2 +- > gcc/testsuite/gcc.dg/tree-ssa/cmple-1.c | 54 +++++++++++++++++++++++++ > 3 files changed, 75 insertions(+), 1 deletion(-) > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/cmple-1.c > > diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc > index dd6ce48f89a..20a670b282a 100644 > --- a/gcc/fold-const.cc > +++ b/gcc/fold-const.cc > @@ -2973,6 +2973,26 @@ combine_comparisons (enum tree_code code, enum > tree_code lcode, > compcode = (~(lcompcode ^ rcompcode)) & 0xf; > break; > > + //`bool0 < bool1` is `!bool0 & bool1` > + case LT_EXPR: > + compcode = (((~lcompcode) & rcompcode)) & 0xf; ... can we make & 0xf less magic? Or maybe ~? (operator ~ on comparison_code?) > + break; > + > + //`bool0 > bool1` is `bool0 & !bool1` > + case GT_EXPR: > + compcode = ((lcompcode & (~rcompcode))) & 0xf; > + break; > + > + // `bool0 <= bool1` as !bool0 | bool1 > + case LE_EXPR: > + compcode = (((~lcompcode) | rcompcode)) & 0xf; > + break; > + > + //`bool0 >= bool1` is `bool0 | !bool1` > + case GE_EXPR: > + compcode = ((lcompcode | (~rcompcode))) & 0xf; > + break; > + > default: > return ERROR_MARK; > } > diff --git a/gcc/match.pd b/gcc/match.pd > index f8251885a7c..374bce45269 100644 > --- a/gcc/match.pd > +++ b/gcc/match.pd > @@ -3621,7 +3621,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) > > /* Optimize (a CMP b) &| (a CMP b) > using the helper combine_comparisons function. */ > -(for bitop (bit_and bit_ior bit_xor ne eq) > +(for bitop (bit_and bit_ior bit_xor simple_comparison) > (for cmp1 (tcc_comparison) > (for cmp2 (tcc_comparison) > (for rcmp (tcc_comparison) > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/cmple-1.c > b/gcc/testsuite/gcc.dg/tree-ssa/cmple-1.c > new file mode 100644 > index 00000000000..8c99180f360 > --- /dev/null > +++ b/gcc/testsuite/gcc.dg/tree-ssa/cmple-1.c > @@ -0,0 +1,54 @@ > +/* { dg-do compile } */ > +/* { dg-options "-O2 -fdump-tree-optimized" } */ > +/* PR tree-optimization/117193 */ > + > +_Bool ltgt_lt(int a, int b) > +{ > + _Bool c = a < b; > + _Bool d = a > b; > + return c < d; // a > b > +} > +/* { dg-final { scan-tree-dump "a_\[0-9\]+.D. > b_\[0-9\]+.D.|b_\[0-9\]+.D. > < a_\[0-9\]+.D." "optimized" } } */ > + > +_Bool lteq_lt(int x, int y) > +{ > + _Bool c = x < y; > + _Bool d = x == y; > + return c < d; // x == y > +} > +/* { dg-final { scan-tree-dump "x_\[0-9\]+.D. == y_\[0-9\]+.D.|y_\[0-9\]+.D. > == x_\[0-9\]+.D." "optimized" } } */ > + > +_Bool ltne_lt(int z, int w) > +{ > + _Bool c = z < w; > + _Bool d = z != w; > + return c < d; // z > w > +} > +/* { dg-final { scan-tree-dump "z_\[0-9\]+.D. > w_\[0-9\]+.D.|w_\[0-9\]+.D. > < y_\[0-9\]+.D." "optimized" } } */ > + > +_Bool lege_lt(int i, int j) > +{ > + _Bool c = i <= j; > + _Bool d = i >= j; > + return c < d; // i > j > +} > +/* { dg-final { scan-tree-dump "i_\[0-9\]+.D. > j_\[0-9\]+.D.|j_\[0-9\]+.D. > < i_\[0-9\]+.D." "optimized" } } */ > + > +_Bool leeq_lt(int k, int l) > +{ > + _Bool c = k <= l; > + _Bool d = k == l; > + return c < d; // 0 > +} > +/* { dg-final { scan-tree-dump "return 0" "optimized" } } */ > +/* { dg-final { scan-tree-dump-not "k_\[0-9\]+.D." "optimized" } } */ > +/* { dg-final { scan-tree-dump-not "l_\[0-9\]+.D." "optimized" } } */ > + > +_Bool lene_lt(int m, int n) > +{ > + _Bool c = m <= n; > + _Bool d = m != n; > + return c < d; // m > n > +} > +/* { dg-final { scan-tree-dump "m_\[0-9\]+.D. > n_\[0-9\]+.D.|n_\[0-9\]+.D. > < m_\[0-9\]+.D." "optimized" } } */ > + > -- > 2.43.0 >
