From: Andrew Pinski <apin...@marvell.com> This patch moves the (a-b) CMP 0 ? (a-b) : (b-a) optimization from fold_cond_expr_with_comparison to match.
OK? Bootstrapped and tested on x86_64-linux-gnu. gcc/ChangeLog: * match.pd ((A-B) CMP 0 ? (A-B) : (B - A)): New patterns. gcc/testsuite/ChangeLog: * gcc.dg/tree-ssa/phi-opt-25.c: New test. --- gcc/match.pd | 48 ++++++++++++++++++++-- gcc/testsuite/gcc.dg/tree-ssa/phi-opt-25.c | 45 ++++++++++++++++++++ 2 files changed, 90 insertions(+), 3 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/phi-opt-25.c diff --git a/gcc/match.pd b/gcc/match.pd index 30680d488ab..aa88381fdcb 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -4040,9 +4040,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (cnd (logical_inverted_value truth_valued_p@0) @1 @2) (cnd @0 @2 @1))) -/* abs/negative simplifications moved from fold_cond_expr_with_comparison, - Need to handle (A - B) case as fold_cond_expr_with_comparison does. - Need to handle UN* comparisons. +/* abs/negative simplifications moved from fold_cond_expr_with_comparison. None of these transformations work for modes with signed zeros. If A is +/-0, the first two transformations will @@ -4098,6 +4096,50 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (convert (negate (absu:utype @0)))) (negate (abs @0))))) ) + + /* (A - B) == 0 ? (A - B) : (B - A) same as (B - A) */ + (for cmp (eq uneq) + (simplify + (cnd (cmp (minus@0 @1 @2) zerop) @0 (minus@3 @2 @1)) + (if (!HONOR_SIGNED_ZEROS (type)) + @3)) + (simplify + (cnd (cmp (minus@0 @1 @2) zerop) integer_zerop (minus@3 @2 @1)) + (if (!HONOR_SIGNED_ZEROS (type)) + @3)) + (simplify + (cnd (cmp @1 @2) integer_zerop (minus@3 @2 @1)) + (if (!HONOR_SIGNED_ZEROS (type)) + @3)) + ) + /* (A - B) != 0 ? (A - B) : (B - A) same as (A - B) */ + (for cmp (ne ltgt) + (simplify + (cnd (cmp (minus@0 @1 @2) zerop) @0 (minus @2 @1)) + (if (!HONOR_SIGNED_ZEROS (type)) + @0)) + ) + /* (A - B) >=/> 0 ? (A - B) : (B - A) same as abs (A - B) */ + (for cmp (ge gt) + (simplify + (cnd (cmp (minus@0 @1 @2) zerop) @0 (minus @2 @1)) + (if (!HONOR_SIGNED_ZEROS (type) + && !TYPE_UNSIGNED (type)) + (abs @0)))) + /* (A - B) <=/< 0 ? (A - B) : (B - A) same as -abs (A - B) */ + (for cmp (le lt) + (simplify + (cnd (cmp (minus@0 @1 @2) zerop) @0 (minus @2 @1)) + (if (!HONOR_SIGNED_ZEROS (type) + && !TYPE_UNSIGNED (type)) + (if (ANY_INTEGRAL_TYPE_P (type) + && !TYPE_OVERFLOW_WRAPS (type)) + (with { + tree utype = unsigned_type_for (type); + } + (convert (negate (absu:utype @0)))) + (negate (abs @0))))) + ) ) /* -(type)!A -> (type)A - 1. */ diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-25.c b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-25.c new file mode 100644 index 00000000000..0f0e3170f8d --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-25.c @@ -0,0 +1,45 @@ +/* { dg-options "-O2 -fno-signed-zeros -fdump-tree-phiopt" } */ +int minus1(int a, int b) +{ + int c = a - b; + if (c == 0) c = b - a; + return c; +} +int minus2(int a, int b) +{ + int c = a - b; + if (c != 0) c = b - a; + return c; +} +int minus3(int a, int b) +{ + int c = a - b; + if (c == 0) c = 0; + else c = b - a; + return c; +} +int minus4(int a, int b) +{ + int c; + if (a == b) c = 0; + else + c = b - a; + return c; +} +int abs0(int a, int b) +{ + int c = a - b; + if (c <= 0) c = b - a; + return c; +} +int negabs(int a, int b) +{ + int c = a - b; + if (c >= 0) c = b - a; + return c; +} + +/* The above should be optimized at phiopt1 except for negabs which has to wait + until phiopt2 as -abs is not acceptable in early phiopt. */ +/* { dg-final { scan-tree-dump-times "if" 1 "phiopt1" } } */ +/* { dg-final { scan-tree-dump-not "if" "phiopt2" } } */ -- 2.27.0