I've checked in the attached patch to fix an oversight in the handling
of GP-relative addressing modes in the nios2 back end. It allows GCC to
generate addresses of the form "%gprel(sym+offset)(gp)" instead of just
"%gprel(sym)(gp)". Formerly GCC required a scratch register and extra
instruction to compute the address in this case, but in fact both the
assembler and underlying relocation support a constant offset with %gprel.
-Sandra
2015-07-05 Chung-Lin Tang <clt...@codesourcery.com>
Sandra Loosemore <san...@codesourcery.com>
gcc/
* config/nios2/nios2-protos.h (nios2_symbol_ref_in_small_data_p):
Delete extern declaration.
(gprel_constant_p): Add extern declaration.
* config/nios2/constraints.md ("S"): Use gprel_constant_p
instead of nios2_symbol_ref_in_small_data_p.
* config/nios2/nios2.c (nios2_legitimate_address_p): Likewise.
(nios2_symbol_ref_in_small_data_p): Make static.
(gprel_constant_p): Make non-static.
gcc/testsuite/
* gcc.target/nios2/gprel-offset.c: New test.
Index: gcc/testsuite/gcc.target/nios2/gprel-offset.c
===================================================================
--- gcc/testsuite/gcc.target/nios2/gprel-offset.c (revision 0)
+++ gcc/testsuite/gcc.target/nios2/gprel-offset.c (revision 0)
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+static struct s {
+ int x;
+ char y;
+} s;
+
+void set (char c)
+{
+ s.y = c;
+}
+
+
+char get (void)
+{
+ return s.y;
+}
+
+/* { dg-final { scan-assembler-times "%gprel\\(s\\+4\\)\\(gp\\)" 2 } } */
Index: gcc/config/nios2/nios2-protos.h
===================================================================
--- gcc/config/nios2/nios2-protos.h (revision 225420)
+++ gcc/config/nios2/nios2-protos.h (working copy)
@@ -44,7 +44,7 @@ extern bool nios2_fpu_insn_enabled (enum
extern const char * nios2_fpu_insn_asm (enum n2fpu_code);
extern bool nios2_legitimate_pic_operand_p (rtx);
-extern bool nios2_symbol_ref_in_small_data_p (rtx);
+extern bool gprel_constant_p (rtx);
extern bool nios2_regno_ok_for_base_p (int, bool);
extern bool nios2_unspec_reloc_p (rtx);
Index: gcc/config/nios2/constraints.md
===================================================================
--- gcc/config/nios2/constraints.md (revision 225419)
+++ gcc/config/nios2/constraints.md (working copy)
@@ -84,8 +84,7 @@
(define_constraint "S"
"An immediate stored in small data, accessible by GP."
- (and (match_code "symbol_ref")
- (match_test "nios2_symbol_ref_in_small_data_p (op)")))
+ (match_test "gprel_constant_p (op)"))
(define_constraint "T"
"A constant unspec offset representing a relocation."
Index: gcc/config/nios2/nios2.c
===================================================================
--- gcc/config/nios2/nios2.c (revision 225420)
+++ gcc/config/nios2/nios2.c (working copy)
@@ -1614,14 +1614,15 @@ nios2_legitimate_address_p (machine_mode
case SYMBOL_REF:
if (SYMBOL_REF_TLS_MODEL (operand))
return false;
-
- if (nios2_symbol_ref_in_small_data_p (operand))
+
+ /* Else, fall through. */
+ case CONST:
+ if (gprel_constant_p (operand))
return true;
/* Else, fall through. */
case LABEL_REF:
case CONST_INT:
- case CONST:
case CONST_DOUBLE:
return false;
@@ -1688,7 +1689,7 @@ nios2_in_small_data_p (const_tree exp)
/* Return true if symbol is in small data section. */
-bool
+static bool
nios2_symbol_ref_in_small_data_p (rtx sym)
{
tree decl;
@@ -2110,7 +2111,7 @@ nios2_print_operand (FILE *file, rtx op,
}
/* Return true if this is a GP-relative accessible reference. */
-static bool
+bool
gprel_constant_p (rtx op)
{
if (GET_CODE (op) == SYMBOL_REF
