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[committed] Tweak ssa-dse-26.c test for c6x after recent SRA changes

Message ID c1ab31fdf91852ac5789bf90e89b595ce9ab0cf3.camel@redhat.com
State New
Headers show
Series [committed] Tweak ssa-dse-26.c test for c6x after recent SRA changes | expand

Commit Message

Jeff Law Jan. 30, 2020, 4:41 p.m. UTC 
The recent SRA changes triggered a testsuite regression on the c6x port
for ssa-dse-26.c.

There was always a degree of difference between the targets, for 
constraint_expr_equal.  Depending on target characteristics there may
or may not be DSE opportunities in this function.

More importantly is constraint_equal.  For most targets we remove an
aggregate assignment to "x" and "y".  We could probably do better than
we are, but that would require further improvements to DSE and perhaps 
one of the redundancy eliminators such as FRE or DOM or twiddles in the
SRA heuristics.

On the c6 we actually remove aggregate stores to "a" and "b" which are
arguments.  Perhaps the differences are related to how structs are
passed accounts for this difference.  Anyway, on the c6x we fully
scalarize the "x" and "y" objects, so there's really nothing for DSE to
do with them.

So this change to the test makes the original pattern we scanned for
apply to everything but the c6x and adds a separate pattern that's only
used on the c6x.  That new pattern checks for the opportunities in both
functions.

Committing to the trunk.  I'm also watching for other targets that may
need similar handling as a result of the SRA work.

Jeff
diff mbox series

Patch

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 0247d2cd083..269adb29e94 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@ 
+2020-01-30  Jeff Law  <law@redhat.com
+
+	* gcc.dg/tree-ssa/ssa-dse-26.c: Make existing dg-final scan
+	conditional on !c6x.  Add dg-final scan pattern for c6x.
+
 2020-01-30  Martin Sebor  <msebor@redhat.com>
 
 	PR middle-end/92323
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-26.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-26.c
index 836a8092ab9..8abc28baccb 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-26.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-26.c
@@ -30,6 +30,13 @@  constraint_equal (struct constraint a, struct constraint b)
     && constraint_expr_equal (a.rhs, b.rhs);
 }
 
-/* { dg-final { scan-tree-dump-times "Deleted dead store: x = " 1 "dse1" } } */
-/* { dg-final { scan-tree-dump-times "Deleted dead store: y = " 1 "dse1" } } */
+/* Most targets should be using this test.  */
+/* { dg-final { scan-tree-dump-times "Deleted dead store: x = " 1 "dse1" { target { ! tic6x-*-* } } } } */
+/* { dg-final { scan-tree-dump-times "Deleted dead store: y = " 1 "dse1" { target { ! tic6x-*-* } } } } */
+
+/* The c6x port generates significantly different gimple which
+   changes the SRA and DSE decisions.   Verify we remove all
+   dead stores.  */
+/* { dg-final { scan-tree-dump-times "Deleted dead store: \[ax\].. = " 2 "dse1" { target tic6x-*-* } } } */
+/* { dg-final { scan-tree-dump-times "Deleted dead store: \[by\].. = " 2 "dse1" { target tic6x-*-* } } } */