[PATCH] arc: check if the addend fits when referencing small data memory [PR115650]

[Yuriy Kolerov]

From: Michiel Derhaeg <mich...@synopsys.com>

This prevents linker errors when referencing small data using large
offsets. In practice it is very unlikely to be a real problem but this
was fixed because other compilers do this check and it ensures the
following tests now succeed:
- gcc.dg/torture/pr60115.c
- gcc.dg/torture/pr105665.c

        PR target/115650

gcc/ChangeLog:

        * config/arc/arc.cc (legitimate_small_data_address_p):
        Check offset size.

gcc/testsuite/ChangeLog:

        * gcc.target/arc/sdata-6.c: New test.

Signed-off-by: Michiel Derhaeg <mich...@synopsys.com>
---
 gcc/config/arc/arc.cc                  | 24 ++++++++++++++++--------
 gcc/testsuite/gcc.target/arc/sdata-6.c | 17 +++++++++++++++++
 2 files changed, 33 insertions(+), 8 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/arc/sdata-6.c

diff --git a/gcc/config/arc/arc.cc b/gcc/config/arc/arc.cc
index 145bc058b09..740b297142b 100644
--- a/gcc/config/arc/arc.cc
+++ b/gcc/config/arc/arc.cc
@@ -386,27 +386,35 @@ legitimate_small_data_address_p (rtx x, machine_mode mode)
       return SYMBOL_REF_SMALL_P (x);
     case PLUS:
       {
-       bool p0 = (GET_CODE (XEXP (x, 0)) == SYMBOL_REF)
-         && SYMBOL_REF_SMALL_P (XEXP (x, 0));
+       if ((GET_CODE (XEXP (x, 0)) != SYMBOL_REF)
+           || !SYMBOL_REF_SMALL_P (XEXP (x, 0)))
+         return false;
 
        /* If no constant then we cannot do small data.  */
        if (!CONST_INT_P (XEXP (x, 1)))
          return false;
 
-       /* Small data relocs works with scalled addresses, check if
+       const int offset = INTVAL (XEXP (x, 1));
+       int size = GET_MODE_SIZE (mode);
+       size = size == 8 ? 4 : size;
+
+       /* Small data relocs works with scaled addresses, check if
           the immediate fits the requirements.  */
-       switch (GET_MODE_SIZE (mode))
+       switch (size)
          {
          case 1:
-           return p0;
+           break;
          case 2:
-           return p0 && ((INTVAL (XEXP (x, 1)) & 0x1) == 0);
+           if ((offset & 0x1) == 0) break; else return false;
          case 4:
-         case 8:
-           return p0 && ((INTVAL (XEXP (x, 1)) & 0x3) == 0);
+           if ((offset & 0x3) == 0) break; else return false;
          default:
            return false;
          }
+
+       /* Reloc allows scaled signed 9 bits.  */
+       const int v = (offset / size) >> 8;
+       return v == 0 || v == -1;
       }
     default:
       return false;
diff --git a/gcc/testsuite/gcc.target/arc/sdata-6.c 
b/gcc/testsuite/gcc.target/arc/sdata-6.c
new file mode 100644
index 00000000000..9b58ac54cbe
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arc/sdata-6.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -msdata" } */
+
+__attribute__((section(".sdata"))) int a[300];
+
+int f (void)
+{
+  return a[255];
+}
+
+int g (void)
+{
+  return a[256];
+}
+
+/* { dg-final { scan-assembler "ld_s\\s+r0,\\\[gp,@a@sda\\+1020\\\]" } } */
+/* { dg-final { scan-assembler "ld\\s+r0,\\\[@a\\+1024\\\]" } } */
-- 
2.34.1