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[PATCH, PR tree-optimization/64277] Improve loop iterations count estimation
- From: Ilya Enkovich <enkovich dot gnu at gmail dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Tue, 27 Jan 2015 12:40:46 +0300
- Subject: [PATCH, PR tree-optimization/64277] Improve loop iterations count estimation
- Authentication-results: sourceware.org; auth=none
Hi,
This patch was supposed to fix PR tree-optimization/64277. Tracker is now fixed by warnings disabling but I think patch is still useful to avoid dead code generated by complete unroll.
Bootstrapped and tested on x86_64-unknown-linux-gnu.
Thanks,
Ilya
--
gcc/
2015-01-27 Ilya Enkovich <ilya.enkovich@intel.com>
* tree-ssa-loop-niter.c (record_nonwrapping_iv): Use base
range info when possible to refine estimation.
gcc/testsuite/
2015-01-27 Ilya Enkovich <ilya.enkovich@intel.com>
* gcc.dg/pr64277.c: New.
diff --git a/gcc/testsuite/gcc.dg/pr64277.c b/gcc/testsuite/gcc.dg/pr64277.c
new file mode 100644
index 0000000..0d5ef11
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr64277.c
@@ -0,0 +1,21 @@
+/* PR tree-optimization/64277 */
+/* { dg-do compile } */
+/* { dg-options "-O3 -Wall -Werror" } */
+
+
+int f1[10];
+void test1 (short a[], short m, unsigned short l)
+{
+ int i = l;
+ for (i = i + 5; i < m; i++)
+ f1[i] = a[i]++;
+}
+
+void test2 (short a[], short m, short l)
+{
+ int i;
+ if (m > 5)
+ m = 5;
+ for (i = m; i > l; i--)
+ f1[i] = a[i]++;
+}
diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c
index 919f5c0..6a55c6f 100644
--- a/gcc/tree-ssa-loop-niter.c
+++ b/gcc/tree-ssa-loop-niter.c
@@ -2754,6 +2754,7 @@ record_nonwrapping_iv (struct loop *loop, tree base, tree step, gimple stmt,
{
tree niter_bound, extreme, delta;
tree type = TREE_TYPE (base), unsigned_type;
+ tree orig_base = base;
if (TREE_CODE (step) != INTEGER_CST || integer_zerop (step))
return;
@@ -2777,16 +2778,32 @@ record_nonwrapping_iv (struct loop *loop, tree base, tree step, gimple stmt,
if (tree_int_cst_sign_bit (step))
{
+ wide_int min, max;
extreme = fold_convert (unsigned_type, low);
- if (TREE_CODE (base) != INTEGER_CST)
+ if (TREE_CODE (orig_base) == SSA_NAME
+ && TREE_CODE (high) == INTEGER_CST
+ && !POINTER_TYPE_P (TREE_TYPE (orig_base))
+ && SSA_NAME_RANGE_INFO (orig_base)
+ && get_range_info (orig_base, &min, &max) == VR_RANGE
+ && wi::gts_p (wide_int (high), max))
+ base = wide_int_to_tree (unsigned_type, max);
+ else if (TREE_CODE (base) != INTEGER_CST)
base = fold_convert (unsigned_type, high);
delta = fold_build2 (MINUS_EXPR, unsigned_type, base, extreme);
step = fold_build1 (NEGATE_EXPR, unsigned_type, step);
}
else
{
+ wide_int min, max;
extreme = fold_convert (unsigned_type, high);
- if (TREE_CODE (base) != INTEGER_CST)
+ if (TREE_CODE (orig_base) == SSA_NAME
+ && TREE_CODE (low) == INTEGER_CST
+ && !POINTER_TYPE_P (TREE_TYPE (orig_base))
+ && SSA_NAME_RANGE_INFO (orig_base)
+ && get_range_info (orig_base, &min, &max) == VR_RANGE
+ && wi::gts_p (min, wide_int (low)))
+ base = wide_int_to_tree (unsigned_type, min);
+ else if (TREE_CODE (base) != INTEGER_CST)
base = fold_convert (unsigned_type, low);
delta = fold_build2 (MINUS_EXPR, unsigned_type, extreme, base);
}