Hi Rainer,
> > The one experiment I'd like to be able to try, to investigate the > > cause/cure of this, is: > > > > diff --git a/gcc/calls.cc b/gcc/calls.cc index a4336c1..05fdd24 100644 > > --- a/gcc/calls.cc > > +++ b/gcc/calls.cc > > @@ -2177,7 +2177,7 @@ load_register_parameters (struct arg_data *args, > > int num_a > > VAR_DECL with a simple constructor, expand that constructor > > via a pseudo rather than read from (possibly misaligned) > > memory. PR middle-end/95126. */ > > - else if (nregs == 1 > > + else if (0 && nregs == 1 > > && partial == 0 > > && !args[i].pass_on_stack > > && VAR_P (tree_value) > > > > My "small const structs" patch affected code generation in three > > places, and identifying which of these is causing the miscompilation > > issue for gnat will help narrow down the problem, or worst case allow > > reverting less of the problematic patch. > > I just tried this on i386-pc-solaris2.11: unfortunately, it made no difference. Awesome! Very many thanks for trying this. Alas it confirms that the patch I'm currently spinning won't have any affect. So by a process of elimination, the miscompilation must be triggered by one of the other two changes: diff --git a/gcc/expr.cc b/gcc/expr.cc index fb062dc..37f1405 100644 --- a/gcc/expr.cc +++ b/gcc/expr.cc @@ -4871,7 +4871,7 @@ emit_push_insn (rtx x, machine_mode mode, tree type, rtx s /* If source is a constant VAR_DECL with a simple constructor, store the constructor to the stack instead of moving it. */ const_tree decl; - if (partial == 0 + if (0 && partial == 0 && MEM_P (xinner) && SYMBOL_REF_P (XEXP (xinner, 0)) && (decl = SYMBOL_REF_DECL (XEXP (xinner, 0))) != NULL_TREE @@ -10603,7 +10603,7 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode t } /* Expand const VAR_DECLs with CONSTRUCTOR initializers that have scalar integer modes to a reg via store_constructor. */ - if (TREE_READONLY (exp) + if (0 && TREE_READONLY (exp) && !TREE_SIDE_EFFECTS (exp) && (modifier == EXPAND_NORMAL || modifier == EXPAND_STACK_PARM) && immediate_const_ctor_p (DECL_INITIAL (exp)) p.s. I've just set up a build environment on another machine where I'm using GNAT 11.3.1 20220421 (Red Hat 11.3.1-2) as the bootstrap compiler, but it'll be a few hours before I'm investigating in gdb. Many thanks again for your help. Sorry again for the breakage/inconvenience. Roger ==