[gcc r12-6513] tree-optimization/76174 - testcase for fixed PR

[Richard Biener]

https://gcc.gnu.org/g:45ddb395187f8f5f278880fe1422d8958ac35da6

commit r12-6513-g45ddb395187f8f5f278880fe1422d8958ac35da6
Author: Richard Biener <rguenther@suse.de>
Date:   Wed Jan 12 08:10:19 2022 +0100

    tree-optimization/76174 - testcase for fixed PR
    
    This adds a testcase for the fixed PR, VN now gets us the transform
    via IV equality plus predication.
    
    2022-01-12  Richard Biener  <rguenther@suse.de>
    
            PR tree-optimization/76174
            * gcc.dg/tree-ssa/pr76174.c: New testcase.

Diff:
---
 gcc/testsuite/gcc.dg/tree-ssa/pr76174.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr76174.c b/gcc/testsuite/gcc.dg/tree-ssa/pr76174.c
new file mode 100644
index 00000000000..17a4a0faf24
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr76174.c
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-cddce1" } */
+
+void foo();
+
+void l(unsigned int r) {
+  	unsigned int q = 0;
+        unsigned int c = r;
+        for (unsigned int x = 0; x<r; x++) {
+            if (q == c) {
+                foo();
+                c *= 2;
+            }
+            q++;
+        }
+}
+
+/* We should be able to elide the body of the function by means of
+   figuring out the equality between the two IVs and then simplifying
+   the q == c test.  */
+/* { dg-final { scan-tree-dump-not "foo" "cddce1" } } */
+/* { dg-final { scan-tree-dump-times "bb" 1 "cddce1" } } */