This patch has bootstrapped and tested on powerpc64le-unknown-linux-gnu
with no regressions. Is this ok for the trunk?
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48344 for the original
problem report. The error resulted because gcc's processing of
command-line options within gcc initialization code originally preceded
the processing of target-specific configuration hooks.
In the unpatched gcc implementation, the Pmode (pointer mode) variable
has not been initialized at the time the -fstack-limit-register
command-line option is processed. As a consequence, the stack-limiting
register is not assigned a proper mode. Thus, rtl instructions that
make use of this stack-limiting register have an unspecified mode, and
are therefore not matched by any known instructions.
The fix represented in this patch is to defer the command-line
processing related to command-line specification of a stack-limiting
register until after target-specific initialization has been completed.
Some questions and issues raised in response to version 2 of this patch
are addressed below:
1. Concerns regarding possible unintended consequences that might result
from moving all target-specific initialization to precede the invocation
of the handle_common_deferred_options () function are addressed by
preserving the original initialization order and moving the relevant
command-line processing to follow the target-specific initialization.
2. A question was raised as to whether Pmode can change with attribute
target. It cannot.
An issue raised in response to version 3 of this patch is addressed as
follows:
1. Abbreviated comments.
2. Fixed spacing following periods within comments.
3. Moved stack_limit_rtx initialization code into init_emit_once(void)
and eliminated special initialization function that had been proposed in
the V3 patch.
gcc/testsuite/ChangeLog:
2016-02-11 Kelvin Nilsen <kel...@gcc.gnu.org>
* gcc.target/powerpc/pr48344-1.c: New test.
gcc/ChangeLog:
2016-02-11 Kelvin Nilsen <kel...@gcc.gnu.org>
* opts-global.c (handle_common_deferred_options): Introduce and
initialize two global variables to remember command-line options
specifying a stack-limiting register.
* opts.h: Add extern declarations of the two new global variables.
* emit-rtl.c (init_emit_once): Initialize the stack_limit_rtx
variable based on the values of the two new global variables.
Index: gcc/testsuite/gcc.target/powerpc/pr48344-1.c
===================================================================
--- gcc/testsuite/gcc.target/powerpc/pr48344-1.c (revision 0)
+++ gcc/testsuite/gcc.target/powerpc/pr48344-1.c (revision 232633)
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-fstack-limit-register=r2" } */
+void foo ()
+{
+ int N = 2;
+ int slots[N];
+
+}
+
Index: gcc/emit-rtl.c
===================================================================
--- gcc/emit-rtl.c (revision 232135)
+++ gcc/emit-rtl.c (working copy)
@@ -57,6 +57,7 @@ along with GCC; see the file COPYING3. If not see
#include "builtins.h"
#include "rtl-iter.h"
#include "stor-layout.h"
+#include "opts.h"
struct target_rtl default_target_rtl;
#if SWITCHABLE_TARGET
@@ -5895,6 +5896,13 @@ init_emit_once (void)
/* Create the unique rtx's for certain rtx codes and operand values. */
+ /* Process stack-limiting command-line options. */
+ if (opt_fstack_limit_symbol_arg != NULL)
+ stack_limit_rtx
+ = gen_rtx_SYMBOL_REF (Pmode, ggc_strdup (opt_fstack_limit_symbol_arg));
+ if (opt_fstack_limit_register_no >= 0)
+ stack_limit_rtx = gen_rtx_REG (Pmode, opt_fstack_limit_register_no);
+
/* Don't use gen_rtx_CONST_INT here since gen_rtx_CONST_INT in this case
tries to use these variables. */
for (i = - MAX_SAVED_CONST_INT; i <= MAX_SAVED_CONST_INT; i++)
Index: gcc/opts.h
===================================================================
--- gcc/opts.h (revision 232135)
+++ gcc/opts.h (working copy)
@@ -296,6 +296,10 @@ struct cl_option_handlers
struct cl_option_handler_func handlers[3];
};
+/* Hold command-line options associated with stack limitation. */
+extern const char *opt_fstack_limit_symbol_arg;
+extern int opt_fstack_limit_register_no;
+
/* Input file names. */
extern const char **in_fnames;
Index: gcc/opts-global.c
===================================================================
--- gcc/opts-global.c (revision 232135)
+++ gcc/opts-global.c (working copy)
@@ -310,6 +310,10 @@ decode_options (struct gcc_options *opts, struct g
finish_options (opts, opts_set, loc);
}
+/* Hold command-line options associated with stack limitation. */
+const char *opt_fstack_limit_symbol_arg = NULL;
+int opt_fstack_limit_register_no = -1;
+
/* Process common options that have been deferred until after the
handlers have been called for all options. */
@@ -417,12 +421,18 @@ handle_common_deferred_options (void)
if (reg < 0)
error ("unrecognized register name %qs", opt->arg);
else
- stack_limit_rtx = gen_rtx_REG (Pmode, reg);
+ {
+ /* Deactivate previous OPT_fstack_limit_symbol_ options. */
+ opt_fstack_limit_symbol_arg = NULL;
+ opt_fstack_limit_register_no = reg;
+ }
}
break;
case OPT_fstack_limit_symbol_:
- stack_limit_rtx = gen_rtx_SYMBOL_REF (Pmode, ggc_strdup (opt->arg));
+ /* Deactivate previous OPT_fstack_limit_register_ options. */
+ opt_fstack_limit_register_no = -1;
+ opt_fstack_limit_symbol_arg = opt->arg;
break;
case OPT_fasan_shadow_offset_:
@@ -442,3 +452,4 @@ handle_common_deferred_options (void)
}
}
}
+
