Hello,

When the DWARF back-end generates DW_OP_neg operations in DWARF
procedures, we get an ICE because of inconsistent stack usage
computation for the embedding expression. This is because
resolve_args_picking_1 thinks DW_OP_neg is a binary operation (pops 2
stack slots, pushes 1) whereas it really is an unary one (one pop, one
push).

This change fixes resolve_args_picking_1 and adds a regression testcase
(which crashes with the current trunk).  Bootstrapped and regtested
without regression on x86_64-linux. Ok to commit?

Thank you in advance!

gcc/

        * dwarf2out.c (resolve_args_picking_1): Consider DW_OP_neg as an
        unary operation, not a binary one.

gcc/testsuite/

        * gnat.dg/debug6.adb, gnat.dg/debug6_pkg.ads: New testcase.
---
 gcc/dwarf2out.c                      |  2 +-
 gcc/testsuite/gnat.dg/debug6.adb     | 10 ++++++++++
 gcc/testsuite/gnat.dg/debug6_pkg.ads | 16 ++++++++++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gnat.dg/debug6.adb
 create mode 100644 gcc/testsuite/gnat.dg/debug6_pkg.ads

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index da95e19..8f192e8 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -15407,6 +15407,7 @@ resolve_args_picking_1 (dw_loc_descr_ref loc, unsigned 
initial_frame_offset,
        case DW_OP_swap:
        case DW_OP_rot:
        case DW_OP_abs:
+       case DW_OP_neg:
        case DW_OP_not:
        case DW_OP_plus_uconst:
        case DW_OP_skip:
@@ -15543,7 +15544,6 @@ resolve_args_picking_1 (dw_loc_descr_ref loc, unsigned 
initial_frame_offset,
        case DW_OP_minus:
        case DW_OP_mod:
        case DW_OP_mul:
-       case DW_OP_neg:
        case DW_OP_or:
        case DW_OP_plus:
        case DW_OP_shl:
diff --git a/gcc/testsuite/gnat.dg/debug6.adb b/gcc/testsuite/gnat.dg/debug6.adb
new file mode 100644
index 0000000..25fdef2
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/debug6.adb
@@ -0,0 +1,10 @@
+-- { dg-do compile }
+-- { dg-options "-g" }
+
+with Debug6_Pkg; use Debug6_Pkg;
+
+procedure Debug6 is
+   V : Value := (Kind => Undefined);
+begin
+   Process (V);
+end Debug6;
diff --git a/gcc/testsuite/gnat.dg/debug6_pkg.ads 
b/gcc/testsuite/gnat.dg/debug6_pkg.ads
new file mode 100644
index 0000000..dfc9744
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/debug6_pkg.ads
@@ -0,0 +1,16 @@
+package Debug6_Pkg is
+
+   type Vkind is (Int, Undefined);
+   for Vkind use (Int => -2 ** 31, Undefined => 0);
+
+    type Value (Kind : Vkind) is record
+       case Kind is
+          when Undefined => null;
+          when Int       => Value : Integer;
+          when others    => null;
+       end case;
+    end record;
+
+    procedure Process (V : Value);
+
+end Debug6_Pkg;
-- 
2.8.2

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