Re: [PATCH v2] Add handling of MULT_EXPR/PLUS_EXPR for wrapping overflow in affine combination(PR83403)

[luoxhu via Gcc-patches]

在 2020-05-06 20:09，Richard Biener 写道：

On Thu, 30 Apr 2020, luoxhu wrote:

Update the patch with overflow check. Bootstrap and regression tested PASS on Power8-LE.

Use determine_value_range to get value range info for fold convert expressions with internal operation PLUS_EXPR/MINUS_EXPR/MULT_EXPR when not overflow on

wrapping overflow inner type.  i.e.:

(long unsigned int)((unsigned  int)n * 10 + 1)
=>
(long unsigned int)n * (long unsigned int)10 + (long unsigned int)1

With this patch for affine combination, load/store motion could detect
more address refs independency and promote some memory expressions to
registers within loop.

PS: Replace the previous "(T1)(X + CST) as (T1)X - (T1)(-CST))"
to "(T1)(X + CST) as (T1)X + (T1)(CST))" for wrapping overflow.

This is OK for trunk if bootstrapped / tested properl.

Bootstrap and regression tested pass on power8LE, committed to
r11-259-g0447929f11e6a3e1b076841712b90a8b6bc7d33a, is it necessary
to backport it to gcc-10&gcc-9?


Thanks,
Xionghu

Thanks,
Richard.

gcc/ChangeLog

        2020-04-30  Xiong Hu Luo  <luo...@linux.ibm.com>

        PR tree-optimization/83403
        * tree-affine.c (expr_to_aff_combination): Replace SSA_NAME with
        determine_value_range, Add fold conversion of MULT_EXPR, fix the
        previous PLUS_EXPR.

gcc/testsuite/ChangeLog

        2020-04-30  Xiong Hu Luo  <luo...@linux.ibm.com>

        PR tree-optimization/83403
        * gcc.dg/tree-ssa/pr83403-1.c: New test.
        * gcc.dg/tree-ssa/pr83403-2.c: New test.
        * gcc.dg/tree-ssa/pr83403.h: New header.
---
 gcc/testsuite/gcc.dg/tree-ssa/pr83403-1.c |  8 ++++++
 gcc/testsuite/gcc.dg/tree-ssa/pr83403-2.c |  8 ++++++

gcc/testsuite/gcc.dg/tree-ssa/pr83403.h | 30 +++++++++++++++++++++++

 gcc/tree-affine.c                         | 24 ++++++++++--------
 4 files changed, 60 insertions(+), 10 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr83403-1.c
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr83403-2.c
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr83403.h

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr83403-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr83403-1.c

new file mode 100644
index 00000000000..748375b03af
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr83403-1.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -funroll-loops -fdump-tree-lim2-details" } */
+
+#define TYPE unsigned int
+
+#include "pr83403.h"
+

+/* { dg-final { scan-tree-dump-times "Executing store motion of" 10 "lim2" } } */ diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr83403-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr83403-2.c

new file mode 100644
index 00000000000..ca2e6bbd61c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr83403-2.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -funroll-loops -fdump-tree-lim2-details" } */
+
+#define TYPE int
+
+#include "pr83403.h"
+

+/* { dg-final { scan-tree-dump-times "Executing store motion of" 10 "lim2" } } */ diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr83403.h b/gcc/testsuite/gcc.dg/tree-ssa/pr83403.h

new file mode 100644
index 00000000000..0da8a835b5f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr83403.h
@@ -0,0 +1,30 @@
+__attribute__ ((noinline)) void

+calculate (const double *__restrict__ A, const double *__restrict__ B,

+          double *__restrict__ C)
+{
+  TYPE m = 0;
+  TYPE n = 0;
+  TYPE k = 0;
+
+  A = (const double *) __builtin_assume_aligned (A, 16);
+  B = (const double *) __builtin_assume_aligned (B, 16);
+  C = (double *) __builtin_assume_aligned (C, 16);
+
+  for (n = 0; n < 9; n++)
+    {
+      for (m = 0; m < 10; m++)
+       {
+         C[(n * 10) + m] = 0.0;
+       }
+
+      for (k = 0; k < 17; k++)
+       {
+#pragma simd
+         for (m = 0; m < 10; m++)
+           {
+             C[(n * 10) + m] += A[(k * 20) + m] * B[(n * 20) + k];
+           }
+       }
+    }
+}
+
diff --git a/gcc/tree-affine.c b/gcc/tree-affine.c
index 0eb8db1b086..5620e6bf28f 100644
--- a/gcc/tree-affine.c
+++ b/gcc/tree-affine.c

@@ -343,24 +343,28 @@ expr_to_aff_combination (aff_tree *comb, tree_code code, tree type,

            wide_int minv, maxv;
            /* If inner type has wrapping overflow behavior, fold conversion
               for below case:
-                (T1)(X - CST) -> (T1)X - (T1)CST

- if X - CST doesn't overflow by range information. Also handle

-              (T1)(X + CST) as (T1)(X - (-CST)).  */
+                (T1)(X *+- CST) -> (T1)X *+- (T1)CST
+              if X *+- CST doesn't overflow by range information.  */
            if (TYPE_UNSIGNED (itype)
                && TYPE_OVERFLOW_WRAPS (itype)
-               && TREE_CODE (op0) == SSA_NAME
                && TREE_CODE (op1) == INTEGER_CST
-               && icode != MULT_EXPR
-               && get_range_info (op0, &minv, &maxv) == VR_RANGE)
+               && determine_value_range (op0, &minv, &maxv) == VR_RANGE)
              {
+               wi::overflow_type overflow = wi::OVF_NONE;
+               signop sign = UNSIGNED;
                if (icode == PLUS_EXPR)
-                 op1 = wide_int_to_tree (itype, -wi::to_wide (op1));
-               if (wi::geu_p (minv, wi::to_wide (op1)))
+                 wi::add (maxv, wi::to_wide (op1), sign, &overflow);
+               else if (icode == MULT_EXPR)
+                 wi::mul (maxv, wi::to_wide (op1), sign, &overflow);
+               else
+                 wi::sub (minv, wi::to_wide (op1), sign, &overflow);
+
+               if (overflow == wi::OVF_NONE)
                  {
                    op0 = fold_convert (otype, op0);
                    op1 = fold_convert (otype, op1);
-                   return expr_to_aff_combination (comb, MINUS_EXPR, otype,
-                                                   op0, op1);
+                   return expr_to_aff_combination (comb, icode, otype, op0,
+                                                   op1);
                  }1
              }
          }