https://gcc.gnu.org/g:578002846620ed04192a4832e9f20b5c32816153
commit r15-5021-g578002846620ed04192a4832e9f20b5c32816153
Author: Andrew Pinski <quic_apin...@quicinc.com>
Date: Fri Nov 1 20:06:30 2024 -0700
VN: Handle `(a | b) !=/== 0` for predicates [PR117414]
For `(a | b) == 0`, we can "assert" on the true edge that
both `a == 0` and `b == 0` but nothing on the false edge.
For `(a | b) != 0`, we can "assert" on the false edge that
both `a == 0` and `b == 0` but nothing on the true edge.
This adds that predicate and allows us to optimize f0, f1,
and f2 in fre-predicated-[12].c.
Changes since v1:
* v2: Use vn_valueize. Also canonicalize the comparison
at the begining of insert_predicates_for_cond for
constants to be on the rhs. Return early for
non-ssa names on the lhs (after canonicalization).
Bootstrapped and tested on x86_64-linux-gnu.
PR tree-optimization/117414
gcc/ChangeLog:
* tree-ssa-sccvn.cc (insert_predicates_for_cond): Canonicalize the
comparison.
Don't insert anything if lhs is not a SSA_NAME. Handle `(a | b)
!=/== 0`.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/fre-predicated-1.c: New test.
* gcc.dg/tree-ssa/fre-predicated-2.c: New test.
Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
Diff:
---
gcc/testsuite/gcc.dg/tree-ssa/fre-predicated-1.c | 53 ++++++++++++++++++++++++
gcc/testsuite/gcc.dg/tree-ssa/fre-predicated-2.c | 27 ++++++++++++
gcc/tree-ssa-sccvn.cc | 36 ++++++++++++++++
3 files changed, 116 insertions(+)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/fre-predicated-1.c
b/gcc/testsuite/gcc.dg/tree-ssa/fre-predicated-1.c
new file mode 100644
index 000000000000..d56952f5f246
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/fre-predicated-1.c
@@ -0,0 +1,53 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+/* PR tree-optimization/117414 */
+
+/* Fre1 should figure out that `*aaa != 0`
+ For f0, f1, and f2. */
+
+
+void foo();
+int f0(int *aaa, int j, int t)
+{
+ int b = *aaa;
+ int c = b != 0;
+ int d = t != 0;
+ if (d | c)
+ return 0;
+ for(int i = 0; i < j; i++)
+ {
+ if (*aaa) foo();
+ }
+ return 0;
+}
+
+int f1(int *aaa, int j, int t)
+{
+ int b = *aaa;
+ if (b != 0 || t != 0)
+ return 0;
+ for(int i = 0; i < j; i++)
+ {
+ if (*aaa) foo();
+ }
+ return 0;
+}
+
+
+int f2(int *aaa, int j, int t)
+{
+ int b = *aaa;
+ if (b != 0)
+ return 0;
+ if (t != 0)
+ return 0;
+ for(int i = 0; i < j; i++)
+ {
+ if (*aaa) foo();
+ }
+ return 0;
+}
+
+/* { dg-final { scan-tree-dump-not "foo " "optimized" } } */
+/* { dg-final { scan-tree-dump "return 0;" "optimized" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/fre-predicated-2.c
b/gcc/testsuite/gcc.dg/tree-ssa/fre-predicated-2.c
new file mode 100644
index 000000000000..0123a5b54f73
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/fre-predicated-2.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+/* PR tree-optimization/117414 */
+
+/* Fre1 should figure out that `*aaa != 0`
+ For f0, f1, and f2. */
+
+
+void foo();
+int f0(int *aaa, int j, int t)
+{
+ int b = *aaa;
+ int d = b | t;
+ if (d == 0)
+ ;
+ else
+ return 0;
+ for(int i = 0; i < j; i++)
+ {
+ if (*aaa) foo();
+ }
+ return 0;
+}
+
+/* { dg-final { scan-tree-dump-not "foo " "optimized" } } */
+/* { dg-final { scan-tree-dump "return 0;" "optimized" } } */
diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
index a11bf9686703..c6dddd0ba6d7 100644
--- a/gcc/tree-ssa-sccvn.cc
+++ b/gcc/tree-ssa-sccvn.cc
@@ -7901,6 +7901,21 @@ static void
insert_predicates_for_cond (tree_code code, tree lhs, tree rhs,
edge true_e, edge false_e)
{
+ /* If both edges are null, then there is nothing to be done. */
+ if (!true_e && !false_e)
+ return;
+
+ /* Canonicalize the comparison so the rhs are constants. */
+ if (CONSTANT_CLASS_P (lhs))
+ {
+ std::swap (lhs, rhs);
+ code = swap_tree_comparison (code);
+ }
+
+ /* If the lhs is not a ssa name, don't record anything. */
+ if (TREE_CODE (lhs) != SSA_NAME)
+ return;
+
tree_code icode = invert_tree_comparison (code, HONOR_NANS (lhs));
tree ops[2];
ops[0] = lhs;
@@ -7929,6 +7944,27 @@ insert_predicates_for_cond (tree_code code, tree lhs,
tree rhs,
if (false_e)
insert_related_predicates_on_edge (icode, ops, false_e);
}
+ if (integer_zerop (rhs)
+ && (code == NE_EXPR || code == EQ_EXPR))
+ {
+ gimple *def_stmt = SSA_NAME_DEF_STMT (lhs);
+ /* (a | b) == 0 ->
+ on true edge assert: a == 0 & b == 0. */
+ /* (a | b) != 0 ->
+ on false edge assert: a == 0 & b == 0. */
+ if (is_gimple_assign (def_stmt)
+ && gimple_assign_rhs_code (def_stmt) == BIT_IOR_EXPR)
+ {
+ edge e = code == EQ_EXPR ? true_e : false_e;
+ tree nlhs;
+
+ nlhs = vn_valueize (gimple_assign_rhs1 (def_stmt));
+ insert_predicates_for_cond (EQ_EXPR, nlhs, rhs, e, nullptr);
+
+ nlhs = vn_valueize (gimple_assign_rhs2 (def_stmt));
+ insert_predicates_for_cond (EQ_EXPR, nlhs, rhs, e, nullptr);
+ }
+ }
}
/* Main stmt worker for RPO VN, process BB. */
