[PATCH] Do not use DW_OP_not for TRUTH_NOT_EXPR in conditional expressions

[Eric Botcazou via Gcc-patches]

Hi,

DW_OP_not is a bitwise, not a logical NOT, so it computes the wrong result in 
a DWARF conditional expression.

Tested (GCC + GDB° on x86-64/Linux, OK for the mainline?


2022-05-13  Eric Botcazou  <ebotca...@adacore.com>

        * dwarf2out.c (loc_list_from_tree_1) <COND_EXPR>: Swap the operands
        if the condition is a TRUTH_NOT_EXPR.

-- 
Eric Botcazou
diff --git a/gcc/dwarf2out.cc b/gcc/dwarf2out.cc
index 5681b01749a..affa2b5e52e 100644
--- a/gcc/dwarf2out.cc
+++ b/gcc/dwarf2out.cc
@@ -19497,6 +19497,15 @@ loc_list_from_tree_1 (tree loc, int want_address,
 	  list_ret
 	    = loc_list_from_tree_1 (TREE_OPERAND (TREE_OPERAND (loc, 0), 0),
 				    0, context);
+	/* DW_OP_not is a bitwise, not a logical NOT, so avoid it.  */
+	else if (TREE_CODE (TREE_OPERAND (loc, 0)) == TRUTH_NOT_EXPR)
+	  {
+	    lhs = loc_descriptor_from_tree (TREE_OPERAND (loc, 2), 0, context);
+	    rhs = loc_list_from_tree_1 (TREE_OPERAND (loc, 1), 0, context);
+	    list_ret
+	      = loc_list_from_tree_1 (TREE_OPERAND (TREE_OPERAND (loc, 0), 0),
+				      0, context);
+	  }
 	else
 	  list_ret = loc_list_from_tree_1 (TREE_OPERAND (loc, 0), 0, context);
 	if (list_ret == 0 || lhs == 0 || rhs == 0)