New patch with the requested changes can be found below. I don't know how much this affects SCEV, but I do believe that we should incorporate this change somehow. I've seen various cases of suboptimal address calculation codegen that boil down to this.
gcc/match.pd | 31 +++++++++++++++++++++++++++++++ gcc/testsuite/gcc.dg/pr109393.c | 16 ++++++++++++++++ 2 files changed, 47 insertions(+) create mode 100644 gcc/testsuite/gcc.dg/pr109393.c diff --git a/gcc/match.pd b/gcc/match.pd index 07e743ae464..1d642c205f0 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -3650,6 +3650,37 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (plus (convert @0) (op @2 (convert @1)))))) #endif +/* ((T)(A + CST1)) * CST2 + CST3 + -> ((T)(A) * CST2) + ((T)CST1 * CST2 + CST3) + Where (A + CST1) doesn't need to have a single use. */ +#if GIMPLE + (for op (plus minus) + (simplify + (plus (mult:s (convert:s (op @0 INTEGER_CST@1)) INTEGER_CST@2) + INTEGER_CST@3) + (if (INTEGRAL_TYPE_P (TREE_TYPE (@0)) + && INTEGRAL_TYPE_P (type) + && TYPE_PRECISION (type) > TYPE_PRECISION (TREE_TYPE (@0)) + && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)) + && !TYPE_OVERFLOW_SANITIZED (TREE_TYPE (@0)) + && TYPE_OVERFLOW_WRAPS (type)) + (op (mult (convert @0) @2) (plus (mult (convert @1) @2) @3))))) +#endif + +/* ((T)(A + CST1)) * CST2 -> ((T)(A) * CST2) + ((T)CST1 * CST2) */ +#if GIMPLE + (for op (plus minus) + (simplify + (mult (convert:s (op:s @0 INTEGER_CST@1)) INTEGER_CST@2) + (if (INTEGRAL_TYPE_P (TREE_TYPE (@0)) + && INTEGRAL_TYPE_P (type) + && TYPE_PRECISION (type) > TYPE_PRECISION (TREE_TYPE (@0)) + && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)) + && !TYPE_OVERFLOW_SANITIZED (TREE_TYPE (@0)) + && TYPE_OVERFLOW_WRAPS (type)) + (op (mult (convert @0) @2) (mult (convert @1) @2))))) +#endif + /* (T)(A) +- (T)(B) -> (T)(A +- B) only when (A +- B) could be simplified to a simple value. */ (for op (plus minus) diff --git a/gcc/testsuite/gcc.dg/pr109393.c b/gcc/testsuite/gcc.dg/pr109393.c new file mode 100644 index 00000000000..e9051273672 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr109393.c @@ -0,0 +1,16 @@ +/* PR tree-optimization/109393 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-optimized" } */ +/* { dg-final { scan-tree-dump-times "return 1;" 2 "optimized" } } */ + +int foo(int *a, int j) +{ + int k = j - 1; + return a[j - 1] == a[k]; +} + +int bar(int *a, int j) +{ + int k = j - 1; + return (&a[j + 1] - 2) == &a[k]; +} -- 2.44.0 On Tue, Apr 23, 2024 at 1:33 PM Manolis Tsamis <manolis.tsa...@vrull.eu> wrote: > > The original motivation for this pattern was that the following function does > not fold to 'return 1': > > int foo(int *a, int j) > { > int k = j - 1; > return a[j - 1] == a[k]; > } > > The expression ((unsigned long) (X +- C1) * C2) appears frequently as part of > address calculations (e.g. arrays). These patterns help fold and simplify more > expressions. > > PR tree-optimization/109393 > > gcc/ChangeLog: > > * match.pd: Add new patterns for ((T)(A +- CST1)) * CST2 and > ((T)(A +- CST1)) * CST2 + CST3. > > gcc/testsuite/ChangeLog: > > * gcc.dg/pr109393.c: New test. > > Signed-off-by: Manolis Tsamis <manolis.tsa...@vrull.eu> > --- > > gcc/match.pd | 30 ++++++++++++++++++++++++++++++ > gcc/testsuite/gcc.dg/pr109393.c | 16 ++++++++++++++++ > 2 files changed, 46 insertions(+) > create mode 100644 gcc/testsuite/gcc.dg/pr109393.c > > diff --git a/gcc/match.pd b/gcc/match.pd > index d401e7503e6..13c828ba70d 100644 > --- a/gcc/match.pd > +++ b/gcc/match.pd > @@ -3650,6 +3650,36 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) > (plus (convert @0) (op @2 (convert @1)))))) > #endif > > +/* ((T)(A + CST1)) * CST2 + CST3 > + -> ((T)(A) * CST2) + ((T)CST1 * CST2 + CST3) > + Where (A + CST1) doesn't need to have a single use. */ > +#if GIMPLE > + (for op (plus minus) > + (simplify > + (plus (mult (convert:s (op @0 INTEGER_CST@1)) INTEGER_CST@2) > INTEGER_CST@3) > + (if (TREE_CODE (TREE_TYPE (@0)) == INTEGER_TYPE > + && TREE_CODE (type) == INTEGER_TYPE > + && TYPE_PRECISION (type) > TYPE_PRECISION (TREE_TYPE (@0)) > + && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)) > + && !TYPE_OVERFLOW_SANITIZED (TREE_TYPE (@0)) > + && TYPE_OVERFLOW_WRAPS (type)) > + (op (mult @2 (convert @0)) (plus (mult @2 (convert @1)) @3))))) > +#endif > + > +/* ((T)(A + CST1)) * CST2 -> ((T)(A) * CST2) + ((T)CST1 * CST2) */ > +#if GIMPLE > + (for op (plus minus) > + (simplify > + (mult (convert:s (op:s @0 INTEGER_CST@1)) INTEGER_CST@2) > + (if (TREE_CODE (TREE_TYPE (@0)) == INTEGER_TYPE > + && TREE_CODE (type) == INTEGER_TYPE > + && TYPE_PRECISION (type) > TYPE_PRECISION (TREE_TYPE (@0)) > + && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)) > + && !TYPE_OVERFLOW_SANITIZED (TREE_TYPE (@0)) > + && TYPE_OVERFLOW_WRAPS (type)) > + (op (mult @2 (convert @0)) (mult @2 (convert @1)))))) > +#endif > + > /* (T)(A) +- (T)(B) -> (T)(A +- B) only when (A +- B) could be simplified > to a simple value. */ > (for op (plus minus) > diff --git a/gcc/testsuite/gcc.dg/pr109393.c b/gcc/testsuite/gcc.dg/pr109393.c > new file mode 100644 > index 00000000000..e9051273672 > --- /dev/null > +++ b/gcc/testsuite/gcc.dg/pr109393.c > @@ -0,0 +1,16 @@ > +/* PR tree-optimization/109393 */ > +/* { dg-do compile } */ > +/* { dg-options "-O2 -fdump-tree-optimized" } */ > +/* { dg-final { scan-tree-dump-times "return 1;" 2 "optimized" } } */ > + > +int foo(int *a, int j) > +{ > + int k = j - 1; > + return a[j - 1] == a[k]; > +} > + > +int bar(int *a, int j) > +{ > + int k = j - 1; > + return (&a[j + 1] - 2) == &a[k]; > +} > -- > 2.34.1 >