re PR tree-optimization/42078 (ICE in gimple_assign_set_rhs_code)

gcc/ChangeLog:
PR tree-optimization/42078
* gimple.h (gimple_replace_lhs): New declaration.
* gimple.c (gimple_replace_lhs): New function.
* tree-ssa-math-opts.c (execute_cse_reciprocals): Call it before
modifying the call.
gcc/testsuite/ChangeLog:
PR tree-optimization/42078
* gcc.dg/pr42078.c: New test.

From-SVN: r154400

1 files changed, 33 insertions, 0 deletions

diff --git a/gcc/gimple.c b/gcc/gimple.c
index 9cec865..f84a20c 100644
--- a/gcc/gimple.c
+++ b/gcc/gimple.c
@@ -1981,6 +1981,39 @@ gimple_set_lhs (gimple stmt, tree lhs)
     gcc_unreachable();
 }
 
+/* Replace the LHS of STMT, an assignment, either a GIMPLE_ASSIGN or a
+   GIMPLE_CALL, with NLHS, in preparation for modifying the RHS to an
+   expression with a different value.
+
+   This will update any annotations (say debug bind stmts) referring
+   to the original LHS, so that they use the RHS instead.  This is
+   done even if NLHS and LHS are the same, for it is understood that
+   the RHS will be modified afterwards, and NLHS will not be assigned
+   an equivalent value.
+
+   Adjusting any non-annotation uses of the LHS, if needed, is a
+   responsibility of the caller.
+
+   The effect of this call should be pretty much the same as that of
+   inserting a copy of STMT before STMT, and then removing the
+   original stmt, at which time gsi_remove() would have update
+   annotations, but using this function saves all the inserting,
+   copying and removing.  */
+
+void
+gimple_replace_lhs (gimple stmt, tree nlhs)
+{
+  if (MAY_HAVE_DEBUG_STMTS)
+    {
+      tree lhs = gimple_get_lhs (stmt);
+
+      gcc_assert (SSA_NAME_DEF_STMT (lhs) == stmt);
+
+      insert_debug_temp_for_var_def (NULL, lhs);
+    }
+
+  gimple_set_lhs (stmt, nlhs);
+}
 
 /* Return a deep copy of statement STMT.  All the operands from STMT
    are reallocated and copied using unshare_expr.  The DEF, USE, VDEF