| Message ID | 20241109035948.2707245-1-quic_apinski@quicinc.com |
|---|---|
| State | New |
| Headers | show |
| Series | fold: Remove (rrotate (rrotate A CST) CST) folding [PR117492] | expand |
> Am 09.11.2024 um 05:00 schrieb Andrew Pinski <quic_apinski@quicinc.com>: > > This removes an (broken) simplification from fold which is already handled in match. > The reason why it was broken is because of the use of wi::to_wide on the RHS of the > rotate which could be 2 different types even though the LHS was the same type. > Since it is already handled in match (by the patterns for > `Turn (a OP c1) OP c2 into a OP (c1+c2).`). It can be removed without losing any optimizations. > > Bootstrapped and tested on x86_64-linux-gnu. Ok Richard > PR middle-end/117492 > > gcc/ChangeLog: > > * fold-const.cc (fold_binary_loc): Remove `Two consecutive rotates adding up > to the some integer` simplifcation. > > gcc/testsuite/ChangeLog: > > * gcc.dg/torture/pr117492-1.c: New test. > > Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com> > --- > gcc/fold-const.cc | 10 ---------- > gcc/testsuite/gcc.dg/torture/pr117492-1.c | 16 ++++++++++++++++ > 2 files changed, 16 insertions(+), 10 deletions(-) > create mode 100644 gcc/testsuite/gcc.dg/torture/pr117492-1.c > > diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc > index 0e374294c01..1e8ae1ab493 100644 > --- a/gcc/fold-const.cc > +++ b/gcc/fold-const.cc > @@ -12530,16 +12530,6 @@ fold_binary_loc (location_t loc, enum tree_code code, tree type, > arg01, arg1)); > } > > - /* Two consecutive rotates adding up to the some integer > - multiple of the precision of the type can be ignored. */ > - if (code == RROTATE_EXPR && TREE_CODE (arg1) == INTEGER_CST > - && TREE_CODE (arg0) == RROTATE_EXPR > - && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST > - && wi::umod_trunc (wi::to_wide (arg1) > - + wi::to_wide (TREE_OPERAND (arg0, 1)), > - prec) == 0) > - return fold_convert_loc (loc, type, TREE_OPERAND (arg0, 0)); > - > return NULL_TREE; > > case MIN_EXPR: > diff --git a/gcc/testsuite/gcc.dg/torture/pr117492-1.c b/gcc/testsuite/gcc.dg/torture/pr117492-1.c > new file mode 100644 > index 00000000000..543d8b7e709 > --- /dev/null > +++ b/gcc/testsuite/gcc.dg/torture/pr117492-1.c > @@ -0,0 +1,16 @@ > +/* { dg-do compile } */ > +/* PR middle-end/117492 */ > + > +/* This code would ICE in fold due to code which was using wi::to_wide with different types > + and adding them. */ > + > +typedef unsigned u; > + > +u > +foo(u x) > +{ > + return > + __builtin_stdc_rotate_left((unsigned) > + __builtin_stdc_rotate_right(x, 0x100000001ull), > + 1); > +} > -- > 2.43.0 >
diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc index 0e374294c01..1e8ae1ab493 100644 --- a/gcc/fold-const.cc +++ b/gcc/fold-const.cc @@ -12530,16 +12530,6 @@ fold_binary_loc (location_t loc, enum tree_code code, tree type, arg01, arg1)); } - /* Two consecutive rotates adding up to the some integer - multiple of the precision of the type can be ignored. */ - if (code == RROTATE_EXPR && TREE_CODE (arg1) == INTEGER_CST - && TREE_CODE (arg0) == RROTATE_EXPR - && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST - && wi::umod_trunc (wi::to_wide (arg1) - + wi::to_wide (TREE_OPERAND (arg0, 1)), - prec) == 0) - return fold_convert_loc (loc, type, TREE_OPERAND (arg0, 0)); - return NULL_TREE; case MIN_EXPR: diff --git a/gcc/testsuite/gcc.dg/torture/pr117492-1.c b/gcc/testsuite/gcc.dg/torture/pr117492-1.c new file mode 100644 index 00000000000..543d8b7e709 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr117492-1.c @@ -0,0 +1,16 @@ +/* { dg-do compile } */ +/* PR middle-end/117492 */ + +/* This code would ICE in fold due to code which was using wi::to_wide with different types + and adding them. */ + +typedef unsigned u; + +u +foo(u x) +{ + return + __builtin_stdc_rotate_left((unsigned) + __builtin_stdc_rotate_right(x, 0x100000001ull), + 1); +}
This removes an (broken) simplification from fold which is already handled in match. The reason why it was broken is because of the use of wi::to_wide on the RHS of the rotate which could be 2 different types even though the LHS was the same type. Since it is already handled in match (by the patterns for `Turn (a OP c1) OP c2 into a OP (c1+c2).`). It can be removed without losing any optimizations. Bootstrapped and tested on x86_64-linux-gnu. PR middle-end/117492 gcc/ChangeLog: * fold-const.cc (fold_binary_loc): Remove `Two consecutive rotates adding up to the some integer` simplifcation. gcc/testsuite/ChangeLog: * gcc.dg/torture/pr117492-1.c: New test. Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com> --- gcc/fold-const.cc | 10 ---------- gcc/testsuite/gcc.dg/torture/pr117492-1.c | 16 ++++++++++++++++ 2 files changed, 16 insertions(+), 10 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/torture/pr117492-1.c