[patch, nios2] add -mgprel-sec= option

[patch, nios2] add -mgprel-sec= option

[Sandra Loosemore]

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I've committed this patch, which allows users to specify additional data 
sections (beyond the normal small-data sections) where GP-relative 
addressing can be used.  It's intended for use on bare-metal nios2-elf 
targets in conjunction with section attributes and a custom linker script.

-Sandra


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2017-10-26  Sandra Loosemore  <sandra@codesourcery.com>

	gcc/
	* config/nios2/nios2.c: Include xregex.h.
	(nios2_gprel_sec_regex): New.
	(nios2_option_overide): Initialize it.  Don't allow GP-relative 
	addressing with PIC.
	(nios2_small_section_name_p): Check for regex match.
	* config/nios2/nios2.opt (mgprel-sec=): New option.
	* doc/invoke.texi (Option Summary): Add -mgprel-sec.
	(Nios II Options): Document -mgprel-sec.

	gcc/testsuite/
	* gcc.target/nios2/gpopt-gprel-sec.c: New.

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diff --git a/gcc/config/nios2/nios2.c b/gcc/config/nios2/nios2.c
index f5963d4..3aade7b 100644
--- a/gcc/config/nios2/nios2.c
+++ b/gcc/config/nios2/nios2.c
@@ -49,6 +49,7 @@
 #include "stor-layout.h"
 #include "builtins.h"
 #include "tree-pass.h"
+#include "xregex.h"
 
 /* This file should be included last.  */
 #include "target-def.h"
@@ -103,6 +104,9 @@ static int custom_code_index[256];
 /* Set to true if any conflicts (re-use of a code between 0-255) are found.  */
 static bool custom_code_conflict = false;
 
+/* State for command-line options.  */
+regex_t nios2_gprel_sec_regex;
+
 \f
 /* Definition of builtin function types for nios2.  */
 
@@ -1371,6 +1375,23 @@ nios2_option_override (void)
 	nios2_gpopt_option = gpopt_local;
     }
 
+  /* GP-relative addressing doesn't make sense for PIC.  */
+  if (flag_pic)
+    { 
+      if (nios2_gpopt_option != gpopt_none)
+        error ("-mgpopt not supported with PIC.");
+      if (nios2_gprel_sec)
+        error ("-mgprel-sec= not supported with PIC.");
+    }
+
+  /* Process -mgprel-sec=.  */
+  if (nios2_gprel_sec)
+    {
+      if (regcomp (&nios2_gprel_sec_regex, nios2_gprel_sec, 
+		   REG_EXTENDED | REG_NOSUB))
+	error ("-mgprel-sec= argument is not a valid regular expression.");
+    }
+
   /* If we don't have mul, we don't have mulx either!  */
   if (!TARGET_HAS_MUL && TARGET_HAS_MULX)
     target_flags &= ~MASK_HAS_MULX;
@@ -2268,7 +2289,9 @@ nios2_small_section_name_p (const char *section)
   return (strcmp (section, ".sbss") == 0
 	  || strncmp (section, ".sbss.", 6) == 0
 	  || strcmp (section, ".sdata") == 0
-	  || strncmp (section, ".sdata.", 7) == 0);
+	  || strncmp (section, ".sdata.", 7) == 0
+	  || (nios2_gprel_sec 
+	      && regexec (&nios2_gprel_sec_regex, section, 0, NULL, 0) == 0));
 }
 
 /* Return true if EXP should be placed in the small data section.  */
diff --git a/gcc/config/nios2/nios2.opt b/gcc/config/nios2/nios2.opt
index 08cb935..d08405e 100644
--- a/gcc/config/nios2/nios2.opt
+++ b/gcc/config/nios2/nios2.opt
@@ -586,3 +586,7 @@ Enable generation of R2 BMX instructions.
 mcdx
 Target Report Mask(HAS_CDX)
 Enable generation of R2 CDX instructions.
+
+mgprel-sec=
+Target RejectNegative Joined Var(nios2_gprel_sec) Init(NULL)
+Regular expression matching additional GP-addressible small-data section names.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 3a87956..0dafdb6 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -948,6 +948,7 @@ Objective-C and Objective-C++ Dialects}.
 
 @emph{Nios II Options}
 @gccoptlist{-G @var{num}  -mgpopt=@var{option}  -mgpopt  -mno-gpopt @gol
+-mgprel-sec=@var{regexp} @gol
 -mel  -meb @gol
 -mno-bypass-cache  -mbypass-cache @gol
 -mno-cache-volatile  -mcache-volatile @gol
@@ -21165,6 +21166,18 @@ GOT data sections.  In this case, the 16-bit offset for GP-relative
 addressing may not be large enough to allow access to the entire 
 small data section.
 
+@item -mgprel-sec=@var{regexp}
+@opindex mgprel-sec
+This option specifies additional section names that can be accessed via
+GP-relative addressing.  It is most useful in conjunction with 
+@code{section} attributes on variable declarations 
+(@pxref{Common Variable Attributes}) and a custom linker script.  
+The @var{regexp} is a POSIX Extended Regular Expression.
+
+This option does not affect the behavior of the @option{-G} option, and 
+and the specified sections are in addition to the standard @code{.sdata} 
+and @code{.sbss} small-data sections that are recognized by @option{-mgpopt}.
+
 @item -mel
 @itemx -meb
 @opindex mel
diff --git a/gcc/testsuite/gcc.target/nios2/gpopt-gprel-sec.c b/gcc/testsuite/gcc.target/nios2/gpopt-gprel-sec.c
new file mode 100644
index 0000000..1083fe6
--- /dev/null
+++ b/gcc/testsuite/gcc.target/nios2/gpopt-gprel-sec.c
@@ -0,0 +1,38 @@
+/* { dg-do compile } */
+/* { dg-options "-O -mgpopt=local -mgprel-sec=\\.frog.+" } */
+
+extern int a __attribute__ ((section (".frog1")));
+static volatile int b __attribute__ ((section (".frog2"))) = 1;
+extern int c __attribute__ ((section (".data")));
+static volatile int d __attribute__ ((section (".data"))) = 2;
+
+extern int e;
+static volatile int f = 3;
+
+volatile int g __attribute__ ((weak)) = 4;
+
+extern int h[100];
+static int i[100];
+static int j[100] __attribute__ ((section (".sdata")));
+
+typedef int (*ftype) (int);
+extern int foo (int);
+
+extern int bar (int, int*, int*, int*, ftype);
+
+int baz (void)
+{
+  return bar (a + b + c + d + e + f + g, h, i, j, foo);
+}
+
+/* { dg-final { scan-assembler "%gprel\\(a\\)" } } */
+/* { dg-final { scan-assembler "%gprel\\(b\\)" } } */
+/* { dg-final { scan-assembler-not "%gprel\\(c\\)" } } */
+/* { dg-final { scan-assembler-not "%gprel\\(d\\)" } } */
+/* { dg-final { scan-assembler-not "%gprel\\(e\\)" } } */
+/* { dg-final { scan-assembler "%gprel\\(f\\)" } } */
+/* { dg-final { scan-assembler-not "%gprel\\(g\\)" } } */
+/* { dg-final { scan-assembler-not "%gprel\\(h\\)" } } */
+/* { dg-final { scan-assembler-not "%gprel\\(i\\)" } } */
+/* { dg-final { scan-assembler "%gprel\\(j\\)" } } */
+/* { dg-final { scan-assembler-not "%gprel\\(foo\\)" } } */