[gcc r14-4729] Fix expansion of `(a & 2) != 1`

[Andrew Pinski <pinskia@gcc.gnu.org>]

https://gcc.gnu.org/g:b20dbddcc41120144e700c4e3ef1ec396b1c56ab

commit r14-4729-gb20dbddcc41120144e700c4e3ef1ec396b1c56ab
Author: Andrew Pinski <pinskia@gmail.com>
Date:   Wed Oct 18 10:26:07 2023 -0700

    Fix expansion of `(a & 2) != 1`
    
    I had a thinko in r14-1600-ge60593f3881c72a96a3fa4844d73e8a2cd14f670
    where we would remove the `& CST` part if we ended up not calling
    expand_single_bit_test.
    This fixes the problem by introducing a new variable that will be used
    for calling expand_single_bit_test.
    As afar as I know this can only show up when disabling optimization
    passes as this above form would have been optimized away.
    
    Committed as obvious after a bootstrap/test on x86_64-linux-gnu.
    
            PR middle-end/111863
    
    gcc/ChangeLog:
    
            * expr.cc (do_store_flag): Don't over write arg0
            when stripping off `& POW2`.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.c-torture/execute/pr111863-1.c: New test.

Diff:
---
 gcc/expr.cc                                      |  9 +++++----
 gcc/testsuite/gcc.c-torture/execute/pr111863-1.c | 16 ++++++++++++++++
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/gcc/expr.cc b/gcc/expr.cc
index 8aed3fc6cbe9..763bd82c59f2 100644
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -13206,14 +13206,15 @@ do_store_flag (sepops ops, rtx target, machine_mode mode)
 	  || integer_pow2p (arg1))
       && (TYPE_PRECISION (ops->type) != 1 || TYPE_UNSIGNED (ops->type)))
     {
-      wide_int nz = tree_nonzero_bits (arg0);
-      gimple *srcstmt = get_def_for_expr (arg0, BIT_AND_EXPR);
+      tree narg0 = arg0;
+      wide_int nz = tree_nonzero_bits (narg0);
+      gimple *srcstmt = get_def_for_expr (narg0, BIT_AND_EXPR);
       /* If the defining statement was (x & POW2), then use that instead of
 	 the non-zero bits.  */
       if (srcstmt && integer_pow2p (gimple_assign_rhs2 (srcstmt)))
 	{
 	  nz = wi::to_wide (gimple_assign_rhs2 (srcstmt));
-	  arg0 = gimple_assign_rhs1 (srcstmt);
+	  narg0 = gimple_assign_rhs1 (srcstmt);
 	}
 
       if (wi::popcount (nz) == 1
@@ -13227,7 +13228,7 @@ do_store_flag (sepops ops, rtx target, machine_mode mode)
 
 	  type = lang_hooks.types.type_for_mode (mode, unsignedp);
 	  return expand_single_bit_test (loc, tcode,
-					 arg0,
+					 narg0,
 					 bitnum, type, target, mode);
 	}
     }
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr111863-1.c b/gcc/testsuite/gcc.c-torture/execute/pr111863-1.c
new file mode 100644
index 000000000000..4e27fe631b21
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr111863-1.c
@@ -0,0 +1,16 @@
+/* { dg-options " -fno-tree-ccp -fno-tree-dominator-opts -fno-tree-vrp" } */
+
+__attribute__((noipa))
+int f(int a)
+{
+        a &= 2;
+        return a != 1;
+}
+int main(void)
+{
+        int t = f(1);
+        if (!t)
+        __builtin_abort();
+        __builtin_printf("%d\n",t);
+        return 0;
+}