[gcc r12-3791] Set bound/cmp/control for until wrap loop.
Jiu Fu Guo
guojiufu@gcc.gnu.org
Wed Sep 22 13:03:55 GMT 2021
https://gcc.gnu.org/g:3087d1b0a2cbe8880ccbbb67744726ff4e5d390e
commit r12-3791-g3087d1b0a2cbe8880ccbbb67744726ff4e5d390e
Author: Jiufu Guo <guojiufu@linux.ibm.com>
Date: Wed Sep 22 13:20:29 2021 +0800
Set bound/cmp/control for until wrap loop.
In patch r12-3136, niter->control, niter->bound and niter->cmp are
derived from number_of_iterations_lt. While for 'until wrap condition',
the calculation in number_of_iterations_lt is not align the requirements
on the define of them and requirements in determine_exit_conditions.
This patch calculate niter->control, niter->bound and niter->cmp in
number_of_iterations_until_wrap.
gcc/ChangeLog:
2021-09-22 Jiufu Guo <guojiufu@linux.ibm.com>
PR tree-optimization/102087
* tree-ssa-loop-niter.c (number_of_iterations_until_wrap):
Update bound/cmp/control for niter.
gcc/testsuite/ChangeLog:
2021-09-22 Jiufu Guo <guojiufu@linux.ibm.com>
* gcc.dg/pr102087.c: New test.
PR tree-optimization/102087
Diff:
---
gcc/testsuite/gcc.dg/pr102087.c | 35 +++++++++++++++++++++++++++++++++++
gcc/tree-ssa-loop-niter.c | 16 +++++++++++++++-
2 files changed, 50 insertions(+), 1 deletion(-)
diff --git a/gcc/testsuite/gcc.dg/pr102087.c b/gcc/testsuite/gcc.dg/pr102087.c
new file mode 100644
index 00000000000..5cd094fc097
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr102087.c
@@ -0,0 +1,35 @@
+/* { dg-do compile } */
+/* { dg-options "-O3" } */
+
+unsigned __attribute__ ((noinline))
+foo (int *__restrict__ a, int *__restrict__ b, unsigned l, unsigned n)
+{
+ while (n < ++l)
+ *a++ = *b++ + 1;
+ return l;
+}
+
+volatile int a[1];
+unsigned b;
+int c;
+
+int
+check ()
+{
+ int d;
+ for (; b > 1; b++)
+ for (c = 0; c < 2; c++)
+ for (d = 0; d < 2; d++)
+ a[0];
+ return 0;
+}
+
+char **clip_image_gfi_0;
+int clip_image_y, clip_image_shift;
+void
+clip_image ()
+{
+ for (; clip_image_y >= clip_image_shift; clip_image_y++)
+ clip_image_gfi_0[clip_image_shift]
+ = clip_image_gfi_0[clip_image_y];
+}
diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c
index 7af92d1c893..75109407124 100644
--- a/gcc/tree-ssa-loop-niter.c
+++ b/gcc/tree-ssa-loop-niter.c
@@ -1482,7 +1482,7 @@ number_of_iterations_until_wrap (class loop *, tree type, affine_iv *iv0,
affine_iv *iv1, class tree_niter_desc *niter)
{
tree niter_type = unsigned_type_for (type);
- tree step, num, assumptions, may_be_zero;
+ tree step, num, assumptions, may_be_zero, span;
wide_int high, low, max, min;
may_be_zero = fold_build2 (LE_EXPR, boolean_type_node, iv1->base, iv0->base);
@@ -1557,6 +1557,20 @@ number_of_iterations_until_wrap (class loop *, tree type, affine_iv *iv0,
niter->control.no_overflow = false;
+ /* Update bound and exit condition as:
+ bound = niter * STEP + (IVbase - STEP).
+ { IVbase - STEP, +, STEP } != bound
+ Here, biasing IVbase by 1 step makes 'bound' be the value before wrap.
+ */
+ niter->control.base = fold_build2 (MINUS_EXPR, niter_type,
+ niter->control.base, niter->control.step);
+ span = fold_build2 (MULT_EXPR, niter_type, niter->niter,
+ fold_convert (niter_type, niter->control.step));
+ niter->bound = fold_build2 (PLUS_EXPR, niter_type, span,
+ fold_convert (niter_type, niter->control.base));
+ niter->bound = fold_convert (type, niter->bound);
+ niter->cmp = NE_EXPR;
+
return true;
}
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