[gcc r14-2480] [range-op] Take known mask into account for bitwise ands [PR107043]

[gcc r14-2480] [range-op] Take known mask into account for bitwise ands [PR107043]

[Aldy Hernandez]

https://gcc.gnu.org/g:7a5e47658904de9dc90f1292f3f69769177706f9

commit r14-2480-g7a5e47658904de9dc90f1292f3f69769177706f9
Author: Aldy Hernandez <aldyh@redhat.com>
Date:   Thu Jul 6 10:55:46 2023 +0200

    [range-op] Take known mask into account for bitwise ands [PR107043]
    
            PR tree-optimization/107043
    
    gcc/ChangeLog:
    
            * range-op.cc (operator_bitwise_and::op1_range): Update bitmask.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.dg/tree-ssa/pr107043.c: New test.

Diff:
---
 gcc/range-op.cc                          |  8 ++++++++
 gcc/testsuite/gcc.dg/tree-ssa/pr107043.c | 22 ++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index 56e80c9f3ae..6b5d4f2accd 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -3463,6 +3463,14 @@ operator_bitwise_and::op1_range (irange &r, tree type,
   if (r.undefined_p ())
     set_nonzero_range_from_mask (r, type, lhs);
 
+  // For MASK == op1 & MASK, all the bits in MASK must be set in op1.
+  wide_int mask;
+  if (lhs == op2 && lhs.singleton_p (mask))
+    {
+      r.update_bitmask (irange_bitmask (mask, ~mask));
+      return true;
+    }
+
   // For 0 = op1 & MASK, op1 is ~MASK.
   if (lhs.zero_p () && op2.singleton_p ())
     {
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr107043.c b/gcc/testsuite/gcc.dg/tree-ssa/pr107043.c
new file mode 100644
index 00000000000..af5df225746
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr107043.c
@@ -0,0 +1,22 @@
+// { dg-do compile }
+// { dg-options "-O2 -fdump-tree-evrp" }
+
+int g0(int n)
+{
+  int n1 = n & 0x8000;
+  if (n1 == 0)
+    return 1;
+  // n1 will be 0x8000 here.
+  return (n1 >> 15) & 0x1;
+}
+
+int g1(int n)
+{
+  int n1 = n & 0x8000;
+  if (n1 == 0)
+    return 1;
+  // n>>15 will be xxxxxx1 here.
+  return (n >> 15) & 0x1;
+}
+
+// { dg-final { scan-tree-dump-times "return 1;" 2 "evrp" } }