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.
Bootstrapped and tested on x86_64-linux-gnu.
Changes in:
v2: Removes `(a == b) ? 0 : (b - a)` handling since it was handled
via r14-3606-g3d86e7f4a8ae
Change zerop to integer_zerop for `(a - b) == 0 ? 0 : (b - a)`,
Add `(a - b) != 0 ? (a - b) : 0` handling.
gcc/ChangeLog:
* match.pd (`(A - B) CMP 0 ? (A - B) : (B - A)`):
New patterns.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/phi-opt-38.c: New test.
---
gcc/match.pd | 46 ++++++++++++++++++++--
gcc/testsuite/gcc.dg/tree-ssa/phi-opt-38.c | 45 +++++++++++++++++++++
2 files changed, 88 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/phi-opt-38.c
diff --git a/gcc/match.pd b/gcc/match.pd
index a56838fb388..ce8d159d260 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -5650,9 +5650,7 @@ 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
@@ -5717,6 +5715,48 @@ 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) integer_zerop) integer_zerop (minus@3 @2 @1))
+ @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))
+ (simplify
+ (cnd (cmp (minus@0 @1 @2) integer_zerop) @0 integer_zerop)
+ @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-38.c
b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-38.c
new file mode 100644
index 00000000000..0f0e3170f8d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-38.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" } } */
--
2.39.3
