On Wed, May 27, 2026 at 8:48 AM Andrew Pinski < [email protected]> wrote:
> On Tue, May 26, 2026 at 7:48 PM Andrew Pinski > <[email protected]> wrote: > > > > On Mon, May 25, 2026 at 8:45 PM Shivam Gupta <[email protected]> > wrote: > > > > > > At -O1, GCC lowers (~a & 1) == (~b & 1) into two different GIMPLE > > > forms depending on whether the boolean values come from a function > > > return boundary or an inline expression: > > > > > > 1. Via function return (e.g. inlined is_even), GCC preserves the > > > eq/ne form because the function boundary hides the internal > > > structure from the gimplifier: > > > ((a&1)==0) == ((b&1)==0) outer node is eq/ne > > > > > > 2. Via inline expression (directly written), GCC sees the full > > > boolean expression tree at once and folds to bit_xor during > > > gimplification: > > > ((a&1)!=0) ^ ((b&1)==0) outer node is bit_xor > > > > > > Add a generalized match.pd rule handling: > > > 1. ((x & c) == 0) OP ((y & c) == 0) > > > 2. ((x & c) != 0) OP ((y & c) == 0) > > > 3. ((x & c) == 0) OP (y & c) > > > > Can you leave out 3 for now? We will need to deal with it later I think. > > It is needed due to: > > ``` > > /* (type)([0,1]@a != 0) -> (type)a > > (type)([0,1]@a == 1) -> (type)a > > (type)([0,1]@a == 0) -> a ^ 1 > > (type)([0,1]@a != 1) -> a ^ 1. */ > > (for eqne (eq ne) > > (simplify > > (convert (eqne zero_one_valued_p@0 INTEGER_CST@1)) > > (if ((integer_zerop (@1) || integer_onep (@1))) > > (if ((eqne == EQ_EXPR) ^ integer_zerop (@1)) > > (convert @0) > > /* Only do this if the types match as (type)(a == 0) is > > canonical form normally, while `a ^ 1` is canonical when > > there is no type change. */ > > (if (types_match (type, TREE_TYPE (@0))) > > (bit_xor @0 { build_one_cst (type); } )))))) > > ``` > > Which was added by > > > https://inbox.sourceware.org/gcc-patches/[email protected]/ > > . > > > > And then we don't support (t1_7 is zero_one_valued_p here): > > _1 = t1_7 == 0; > > _2 = (int) _1; > > > > Into: > > _t = (t1_7^1) > > _2 = (int)_t; > > > > As types_match is not true. That was not done . > > > > I didn't realize this came into play for the `&1` part until now :). > > > > You can keep the testcases for the ones which will match 3 but xfail > them. > > That is because we should handle it differently and separately as that > only matters with `&1` there. > > The pattern there will be something like > (ne zero_one_valued_p@0 (convert? (eq zero_one_valued_p@1 integer_zerop))) > simplified to: > (eq (convert:TREE_TYPE(@1) @0) @1) > > With that pattern, this: > t1_5 = a_4(D) & 1; > t2_7 = b_6(D) & 1; // t2_7 is zero_one_valued_p > _1 = t1_5 == 0; > _2 = (int) _1; // _2 is zero_one_valued_p > _3 = (int) t2_7; // _3 is zero_one_valued_p > _8 = _2 != _3; > return _8; > > Will gets turned into: > _8 = t2_7 == t1_5 > > OK, I can try that in some time as a different patch. Thanks, Shivam Thanks, > Drea > > > > > Thanks, > > Andrea > > > > > > > > > > > > for OP in { ==, !=, ^ } and pow2 masks. The third form is required > > > because GCC canonicalize: ((x & c) != 0) into (x & c) before this > > > rule runs. > > > > > > Fold these directly into the canonical xor-mask form: > > > ((x ^ y) & c) == 0 > > > ((x ^ y) & c) != 0 > > > > > > Bootstrapped and tested on aarch64-linux-gnu. > > > > > > Changes since v1: > > > * v3: Collapse both previous simplify rules into one generalized > > > matcher covering all combinations of outer {eq, ne, bit_xor} > > > and inner {eq, ne} comparisons. > > > Add missing mixed-polarity test cases. > > > > > > * v2: Generalize mask from integer_onep to integer_pow2p. > > > Combine both patterns into single one. > > > Split test into bool-eq-evenness.c, bool-eq-bitxor.c, > > > bool-eq-pow2.c. > > > > > > PR tree-optimization/112533 > > > gcc/ChangeLog: > > > * match.pd: Canonicalize boolean comparisons of masked pow2 > > > bits into xor-mask tests. > > > > > > gcc/testsuite/ChangeLog: > > > * gcc.dg/tree-ssa/bool-eq-bitxor.c: New test. > > > * gcc.dg/tree-ssa/bool-eq-evenness.c: New test. > > > * gcc.dg/tree-ssa/bool-eq-pow2.c: New test. > > > > > > Signed-off-by: Shivam Gupta <[email protected]> > > > --- > > > gcc/match.pd | 38 ++++++++ > > > .../gcc.dg/tree-ssa/bool-eq-bitxor.c | 39 ++++++++ > > > .../gcc.dg/tree-ssa/bool-eq-evenness.c | 43 +++++++++ > > > gcc/testsuite/gcc.dg/tree-ssa/bool-eq-pow2.c | 89 +++++++++++++++++++ > > > 4 files changed, 209 insertions(+) > > > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/bool-eq-bitxor.c > > > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/bool-eq-evenness.c > > > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/bool-eq-pow2.c > > > > > > diff --git a/gcc/match.pd b/gcc/match.pd > > > index ff13a07ea94..d41a2b2f329 100644 > > > --- a/gcc/match.pd > > > +++ b/gcc/match.pd > > > @@ -1464,6 +1464,44 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) > > > (if (TYPE_UNSIGNED (type)) > > > (bit_and @0 (bit_not (lshift { build_all_ones_cst (type); } > @1))))) > > > > > > +/* PR112533: Canonicalize boolean comparisons of masked pow2 bits into > > > + xor-mask tests. > > > + ((x & c) == 0) == ((y & c) == 0) -> (((x ^ y) & c) == 0) > > > + ((x & c) == 0) != ((y & c) == 0) -> (((x ^ y) & c) != 0) > > > + and equivalent xor forms. */ > > > +(for ocmp (eq ne bit_xor) > > > + (for icmp0 (eq eq ne ne) > > > + icmp1 (eq ne eq ne) > > > + (simplify > > > + (ocmp > > > + (icmp0 (bit_and @0 integer_pow2p@1) integer_zerop@3) > > > + (icmp1 (bit_and @2 @1) @3)) > > > + (if (types_match (@0, @2)) > > > + (with { > > > + bool innersame > > > + = (icmp0 == EQ_EXPR) == (icmp1 == EQ_EXPR); > > > + } > > > + (if (innersame == (ocmp == EQ_EXPR)) > > > + (eq (bit_and (bit_xor @0 @2) @1) @3) > > > + (ne (bit_and (bit_xor @0 @2) @1) @3))))) > > > + > > > + /* Canonicalized: ((x & c) == 0) OP (y & c) > > > + because ((y & c) != 0) may fold into (y & c). */ > > > + (simplify > > > + (ocmp > > > + (convert?@4 > > > + (icmp0 (bit_and @0 integer_pow2p@1) integer_zerop@3)) > > > + (convert?@5 > > > + (bit_and @2 @1))) > > > + (if (types_match (@0, @2)) > > > + (with { > > > + bool innersame > > > + = (icmp0 == EQ_EXPR) == false; > > > + } > > > + (if (innersame == (ocmp == EQ_EXPR)) > > > + (eq (bit_and (bit_xor @0 @2) @1) @3) > > > + (ne (bit_and (bit_xor @0 @2) @1) @3))))))) > > > + > > > (for bitop (bit_and bit_ior) > > > cmp (eq ne) > > > /* PR35691: Transform > > > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/bool-eq-bitxor.c > b/gcc/testsuite/gcc.dg/tree-ssa/bool-eq-bitxor.c > > > new file mode 100644 > > > index 00000000000..05cee9696cf > > > --- /dev/null > > > +++ b/gcc/testsuite/gcc.dg/tree-ssa/bool-eq-bitxor.c > > > @@ -0,0 +1,39 @@ > > > +/* { dg-do compile } */ > > > +/* { dg-options "-O1 -fdump-tree-optimized" } */ > > > + > > > +typedef unsigned int u32; > > > + > > > +_Bool > > > +xor_ne_eq (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 1; > > > + u32 t2 = b & 1; > > > + return (t1 != 0) ^ (t2 == 0); > > > +} > > > + > > > +_Bool > > > +xor_eq_eq (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 1; > > > + u32 t2 = b & 1; > > > + return (t1 == 0) ^ (t2 == 0); > > > +} > > > + > > > +_Bool > > > +xor_eq_ne (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 1; > > > + u32 t2 = b & 1; > > > + return (t1 == 0) ^ (t2 != 0); > > > +} > > > + > > > +_Bool > > > +xor_ne_ne (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 1; > > > + u32 t2 = b & 1; > > > + return (t1 != 0) ^ (t2 != 0); > > > +} > > > + > > > +/* Verify all functions canonicalize to xor-mask tests. */ > > > +/* { dg-final { scan-tree-dump-times "& 1" 4 "optimized" } } */ > > > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/bool-eq-evenness.c > b/gcc/testsuite/gcc.dg/tree-ssa/bool-eq-evenness.c > > > new file mode 100644 > > > index 00000000000..75df70dc6a4 > > > --- /dev/null > > > +++ b/gcc/testsuite/gcc.dg/tree-ssa/bool-eq-evenness.c > > > @@ -0,0 +1,43 @@ > > > +/* { dg-do compile } */ > > > +/* { dg-options "-O1 -fdump-tree-optimized" } */ > > > + > > > +/* Verify the GIMPLE-level fix for PR112533. */ > > > + > > > +typedef unsigned int u32; > > > + > > > +static _Bool > > > +is_even (u32 a) > > > +{ > > > + return a % 2 == 0; > > > +} > > > + > > > +_Bool > > > +same_evenness (u32 a, u32 b) > > > +{ > > > + return is_even (a) == is_even (b); > > > +} > > > + > > > +_Bool > > > +diff_evenness (u32 a, u32 b) > > > +{ > > > + return is_even (a) != is_even (b); > > > +} > > > + > > > +_Bool > > > +same_evenness_cmp_zero (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 1; > > > + u32 t2 = b & 1; > > > + return (t1 == 0) == (t2 == 0); > > > +} > > > + > > > +_Bool > > > +diff_evenness_cmp_zero (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 1; > > > + u32 t2 = b & 1; > > > + return (t1 == 0) != (t2 == 0); > > > +} > > > + > > > +/* Verify all functions canonicalize to xor forms. */ > > > +/* { dg-final { scan-tree-dump-times "\\^" 4 "optimized" } } */ > > > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/bool-eq-pow2.c > b/gcc/testsuite/gcc.dg/tree-ssa/bool-eq-pow2.c > > > new file mode 100644 > > > index 00000000000..109c5f03610 > > > --- /dev/null > > > +++ b/gcc/testsuite/gcc.dg/tree-ssa/bool-eq-pow2.c > > > @@ -0,0 +1,89 @@ > > > +/* { dg-do compile } */ > > > +/* { dg-options "-O1 -fdump-tree-optimized" } */ > > > + > > > +typedef unsigned int u32; > > > + > > > +_Bool > > > +eq_eq_outer_eq_mask2 (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 2; > > > + u32 t2 = b & 2; > > > + return (t1 == 0) == (t2 == 0); > > > +} > > > + > > > +_Bool > > > +eq_eq_outer_eq_mask4 (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 4; > > > + u32 t2 = b & 4; > > > + return (t1 == 0) == (t2 == 0); > > > +} > > > + > > > +_Bool > > > +eq_eq_outer_ne (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 1; > > > + u32 t2 = b & 1; > > > + return (t1 == 0) != (t2 == 0); > > > +} > > > + > > > +_Bool > > > +ne_eq_outer_eq (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 1; > > > + u32 t2 = b & 1; > > > + return (t1 != 0) == (t2 == 0); > > > +} > > > + > > > +_Bool > > > +ne_eq_outer_ne (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 1; > > > + u32 t2 = b & 1; > > > + return (t1 != 0) != (t2 == 0); > > > +} > > > + > > > +_Bool > > > +eq_ne_outer_eq (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 1; > > > + u32 t2 = b & 1; > > > + return (t1 == 0) == (t2 != 0); > > > +} > > > + > > > +_Bool > > > +eq_ne_outer_ne (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 1; > > > + u32 t2 = b & 1; > > > + return (t1 == 0) != (t2 != 0); > > > +} > > > + > > > +_Bool > > > +ne_ne_outer_eq (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 1; > > > + u32 t2 = b & 1; > > > + return (t1 != 0) == (t2 != 0); > > > +} > > > + > > > +_Bool > > > +ne_ne_outer_ne (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 1; > > > + u32 t2 = b & 1; > > > + return (t1 != 0) != (t2 != 0); > > > +} > > > + > > > +/* Non-power-of-2: should not be simplified. */ > > > +_Bool > > > +eq_eq_outer_eq_nonpow2 (u32 a, u32 b) > > > +{ > > > + u32 t1 = a & 3; > > > + u32 t2 = b & 3; > > > + return (t1 == 0) == (t2 == 0); > > > +} > > > + > > > +/* Verify power-of-2 masks are simplified, non-power-of-2 masks are > not. */ > > > +/* { dg-final { scan-tree-dump-times "a_\[0-9\]+\\(D\\) \\^ > b_\[0-9\]+\\(D\\)" 9 "optimized" } } */ > > > +/* { dg-final { scan-tree-dump-times "& 3" 2 "optimized" } } */ > > > -- > > > 2.34.1 > > > >
