diff mbox series

[3/5] Match: Simplify branch form 8 of unsigned SAT_ADD into branchless

Message ID 20241029082521.3638409-3-pan2.li@intel.com
State New
Headers
Series [1/5] Match: Simplify branch form 4 of unsigned SAT_ADD into branchless |

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Context Check Description
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linaro-tcwg-bot/tcwg_gcc_build--master-aarch64 success Build passed

Commit Message

Li, Pan2 Oct. 29, 2024, 8:25 a.m. UTC 
  From: Pan Li <pan2.li@intel.com>

There are sorts of forms for the unsigned SAT_ADD.  Some of them are
complicated while others are cheap.  This patch would like to simplify
the complicated form into the cheap ones.  For example as below:

From the form 8 (branch):
  SAT_U_ADD = x > (T)(x + y) ? -1 : (x + y).

To (branchless):
  SAT_U_ADD = (X + Y) | - ((X + Y) < X).

  #define T uint8_t

  T sat_add_u_1 (T x, T y)
  {
    return x > (T)(x + y) ? -1 : (x + y);
  }

Before this patch:
   1   │ uint8_t sat_add_u_1 (uint8_t x, uint8_t y)
   2   │ {
   3   │   uint8_t D.2809;
   4   │
   5   │   _1 = x + y;
   6   │   if (x <= _1) goto <D.2810>; else goto <D.2811>;
   7   │   <D.2810>:
   8   │   D.2809 = x + y;
   9   │   goto <D.2812>;
  10   │   <D.2811>:
  11   │   D.2809 = 255;
  12   │   <D.2812>:
  13   │   return D.2809;
  14   │ }

After this patch:
   1   │ uint8_t sat_add_u_1 (uint8_t x, uint8_t y)
   2   │ {
   3   │   uint8_t D.2809;
   4   │
   5   │   _1 = x + y;
   6   │   _2 = x + y;
   7   │   _3 = x > _2;
   8   │   _4 = (unsigned char) _3;
   9   │   _5 = -_4;
  10   │   D.2809 = _1 | _5;
  11   │   return D.2809;
  12   │ }

The simplify doesn't need to check if target support the SAT_ADD, it
is somehow the optimization in gimple level.

The below test suites are passed for this patch.
* The rv64gcv fully regression test.
* The x86 bootstrap test.
* The x86 fully regression test.

gcc/ChangeLog:

	* match.pd: Remove unsigned branch form 8 for SAT_ADD, and
	add simplify to branchless instead.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/sat_u_add-simplify-4-u16.c: New test.
	* gcc.dg/tree-ssa/sat_u_add-simplify-4-u32.c: New test.
	* gcc.dg/tree-ssa/sat_u_add-simplify-4-u64.c: New test.
	* gcc.dg/tree-ssa/sat_u_add-simplify-4-u8.c: New test.

Signed-off-by: Pan Li <pan2.li@intel.com>
---
 gcc/match.pd                                      | 13 ++++++++-----
 .../gcc.dg/tree-ssa/sat_u_add-simplify-4-u16.c    | 15 +++++++++++++++
 .../gcc.dg/tree-ssa/sat_u_add-simplify-4-u32.c    | 15 +++++++++++++++
 .../gcc.dg/tree-ssa/sat_u_add-simplify-4-u64.c    | 15 +++++++++++++++
 .../gcc.dg/tree-ssa/sat_u_add-simplify-4-u8.c     | 15 +++++++++++++++
 5 files changed, 68 insertions(+), 5 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u16.c
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u32.c
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u64.c
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u8.c
diff mbox series

Patch

diff --git a/gcc/match.pd b/gcc/match.pd
index d871fb8c24e..7105aedb40c 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -3170,6 +3170,14 @@  DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
       && types_match (type, @0, @1))
   (bit_ior @2 (negate (convert (lt @2 @0))))))
 
+/* Simplify SAT_U_ADD to the cheap form
+   From: SAT_U_ADD = x > (X + Y) ? -1 : (X + Y).
+   To:   SAT_U_ADD = (X + Y) | - ((X + Y) < X).  */
+(simplify (cond (gt @0 (plus:c@2 @0 @1)) integer_minus_onep @2)
+ (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
+      && types_match (type, @0, @1))
+  (bit_ior @2 (negate (convert (lt @2 @0))))))
+
 /* Unsigned saturation add, case 5 (branch with eq .ADD_OVERFLOW):
    SAT_U_ADD = REALPART_EXPR <.ADD_OVERFLOW> == 0 ? .ADD_OVERFLOW : -1.  */
 (match (unsigned_integer_sat_add @0 @1)
@@ -3182,11 +3190,6 @@  DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  (cond^ (ne (imagpart (IFN_ADD_OVERFLOW:c @0 @1)) integer_zerop)
   integer_minus_onep (usadd_left_part_2 @0 @1)))
 
-/* Unsigned saturation add, case 8 (branch with gt):
-   SAT_ADD = x > (X + Y) ? -1 : (X + Y).  */
-(match (unsigned_integer_sat_add @0 @1)
- (cond^ (gt @0 (usadd_left_part_1@2 @0 @1)) integer_minus_onep @2))
-
 /* Unsigned saturation add, case 9 (one op is imm):
    SAT_U_ADD = (X + 3) >= x ? (X + 3) : -1.  */
 (match (unsigned_integer_sat_add @0 @1)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u16.c b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u16.c
new file mode 100644
index 00000000000..bc899715dd6
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u16.c
@@ -0,0 +1,15 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-gimple-details" } */
+
+#include <stdint.h>
+
+#define T uint16_t
+
+T sat_add_u_1 (T x, T y)
+{
+  return x > (T)(x + y) ? -1 : (x + y);
+}
+
+/* { dg-final { scan-tree-dump-not " if " "gimple" } } */
+/* { dg-final { scan-tree-dump-not " else " "gimple" } } */
+/* { dg-final { scan-tree-dump-not " goto " "gimple" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u32.c b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u32.c
new file mode 100644
index 00000000000..53d6033563a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u32.c
@@ -0,0 +1,15 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-gimple-details" } */
+
+#include <stdint.h>
+
+#define T uint32_t
+
+T sat_add_u_1 (T x, T y)
+{
+  return x > (T)(x + y) ? -1 : (x + y);
+}
+
+/* { dg-final { scan-tree-dump-not " if " "gimple" } } */
+/* { dg-final { scan-tree-dump-not " else " "gimple" } } */
+/* { dg-final { scan-tree-dump-not " goto " "gimple" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u64.c b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u64.c
new file mode 100644
index 00000000000..772f64a9bae
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u64.c
@@ -0,0 +1,15 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-gimple-details" } */
+
+#include <stdint.h>
+
+#define T uint64_t
+
+T sat_add_u_1 (T x, T y)
+{
+  return x > (T)(x + y) ? -1 : (x + y);
+}
+
+/* { dg-final { scan-tree-dump-not " if " "gimple" } } */
+/* { dg-final { scan-tree-dump-not " else " "gimple" } } */
+/* { dg-final { scan-tree-dump-not " goto " "gimple" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u8.c b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u8.c
new file mode 100644
index 00000000000..6c91fe7ec5d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-4-u8.c
@@ -0,0 +1,15 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-gimple-details" } */
+
+#include <stdint.h>
+
+#define T uint8_t
+
+T sat_add_u_1 (T x, T y)
+{
+  return x > (T)(x + y) ? -1 : (x + y);
+}
+
+/* { dg-final { scan-tree-dump-not " if " "gimple" } } */
+/* { dg-final { scan-tree-dump-not " else " "gimple" } } */
+/* { dg-final { scan-tree-dump-not " goto " "gimple" } } */