Implement attribute progmem on reduced Tiny cores by adding flash offset 0x4000…

Implement attribute progmem on reduced Tiny cores by adding flash offset 0x4000 to respective symbols.

gcc/
	Implement attribute progmem on reduced Tiny cores by adding
	flash offset 0x4000 to respective symbols.

	PR target/71948
	* doc/extend.texi (AVR Variable Attributes) [progmem]: Add
	documentation how it works on reduced Tiny cores.
	(AVR Named Address Spaces): No support for reduced Tiny.
	* config/avr/avr.c (AVR_SYMBOL_FLAG_TINY_PM): New macro.
	(avr_address_tiny_pm_p): New static function.
	(avr_print_operand_address) [AVR_TINY]: Add AVR_TINY_PM_OFFSET
	if the address is in progmem.
	(avr_assemble_integer): Same.
	(avr_encode_section_info) [AVR_TINY]: Set AVR_SYMBOL_FLAG_TINY_PM
	for symbol_ref in progmem.
	* config/avr/avr.h (AVR_TINY_PM_OFFSET): New macro.
	* config/avr/avr-c.c (avr_cpu_cpp_builtins): Use it instead of
	magic 0x4000 when built-in def'ing __AVR_TINY_PM_BASE_ADDRESS__.
gcc/testsuite/
	PR target/71948
	* gcc.target/avr/torture/tiny-progmem.c: New test.

From-SVN: r238525

gcc/ChangeLog

+2016-07-20  Georg-Johann Lay  <avr@gjlay.de>
+
+	Implement attribute progmem on reduced Tiny cores by adding
+	flash offset 0x4000 to respective symbols.
+
+	PR target/71948
+	* doc/extend.texi (AVR Variable Attributes) [progmem]: Add
+	documentation how it works on reduced Tiny cores.
+	(AVR Named Address Spaces): No support for reduced Tiny.
+	* config/avr/avr.c (AVR_SYMBOL_FLAG_TINY_PM): New macro.
+	(avr_address_tiny_pm_p): New static function.
+	(avr_print_operand_address) [AVR_TINY]: Add AVR_TINY_PM_OFFSET
+	if the address is in progmem.
+	(avr_assemble_integer): Same.
+	(avr_encode_section_info) [AVR_TINY]: Set AVR_SYMBOL_FLAG_TINY_PM
+	for symbol_ref in progmem.
+	* config/avr/avr.h (AVR_TINY_PM_OFFSET): New macro.
+	* config/avr/avr-c.c (avr_cpu_cpp_builtins): Use it instead of
+	magic 0x4000 when built-in def'ing __AVR_TINY_PM_BASE_ADDRESS__.
+
 2016-07-20  Patrick Palka  <ppalka@gcc.gnu.org>
 
 	* configure.ac (thin_archive_support): New variable.  AC_SUBST it.

gcc/config/avr/avr-c.c

@@ -296,7 +296,7 @@ avr_cpu_cpp_builtins (struct cpp_reader *pfile)
   builtin_define_std ("AVR");
 
   /* __AVR_DEVICE_NAME__ and  avr_mcu_types[].macro like __AVR_ATmega8__
-	 are defined by -D command option, see device-specs file.  */
+     are defined by -D command option, see device-specs file.  */
 
   if (avr_arch->macro)
     cpp_define_formatted (pfile, "__AVR_ARCH__=%s", avr_arch->macro);
@@ -337,7 +337,8 @@ avr_cpu_cpp_builtins (struct cpp_reader *pfile)
          it has been mapped to the data memory.  For AVR_TINY devices
          (ATtiny4/5/9/10/20 and 40) mapped program memory starts at 0x4000. */
 
-      cpp_define (pfile, "__AVR_TINY_PM_BASE_ADDRESS__=0x4000");
+      cpp_define_formatted (pfile, "__AVR_TINY_PM_BASE_ADDRESS__=0x%x",
+                            AVR_TINY_PM_OFFSET);
     }
 
   if (AVR_HAVE_EIJMP_EICALL)

gcc/config/avr/avr.c

@@ -80,6 +80,10 @@
   ((SYMBOL_REF_FLAGS (sym) & AVR_SYMBOL_FLAG_PROGMEM)           \
    / SYMBOL_FLAG_MACH_DEP)
 
+/* (AVR_TINY only): Symbol has attribute progmem */
+#define AVR_SYMBOL_FLAG_TINY_PM \
+  (SYMBOL_FLAG_MACH_DEP << 4)
+
 #define TINY_ADIW(REG1, REG2, I)                                \
     "subi " #REG1 ",lo8(-(" #I "))" CR_TAB                      \
     "sbci " #REG2 ",hi8(-(" #I "))"
@@ -2161,12 +2165,35 @@ cond_string (enum rtx_code code)
 }
 
 
+/* Return true if rtx X is a CONST or SYMBOL_REF with progmem.
+   This must be used for AVR_TINY only because on other cores
+   the flash memory is not visible in the RAM address range and
+   cannot be read by, say,  LD instruction.  */
+
+static bool
+avr_address_tiny_pm_p (rtx x)
+{
+  if (CONST == GET_CODE (x))
+    x = XEXP (XEXP (x, 0), 0);
+
+  if (SYMBOL_REF_P (x))
+    return SYMBOL_REF_FLAGS (x) & AVR_SYMBOL_FLAG_TINY_PM;
+
+  return false;
+}
+
 /* Implement `TARGET_PRINT_OPERAND_ADDRESS'.  */
 /* Output ADDR to FILE as address.  */
 
 static void
 avr_print_operand_address (FILE *file, machine_mode /*mode*/, rtx addr)
 {
+  if (AVR_TINY
+      && avr_address_tiny_pm_p (addr))
+    {
+      addr = plus_constant (Pmode, addr, AVR_TINY_PM_OFFSET);
+    }
+
   switch (GET_CODE (addr))
     {
     case REG:
@@ -8937,6 +8964,12 @@ avr_assemble_integer (rtx x, unsigned int size, int aligned_p)
       return true;
     }
 
+  if (AVR_TINY
+      && avr_address_tiny_pm_p (x))
+    {
+      x = plus_constant (Pmode, x, AVR_TINY_PM_OFFSET);
+    }
+
   return default_assemble_integer (x, size, aligned_p);
 }
 
@@ -9603,7 +9636,7 @@ avr_encode_section_info (tree decl, rtx rtl, int new_decl_p)
   if (decl && DECL_P (decl)
       && TREE_CODE (decl) != FUNCTION_DECL
       && MEM_P (rtl)
-      && SYMBOL_REF == GET_CODE (XEXP (rtl, 0)))
+      && SYMBOL_REF_P (XEXP (rtl, 0)))
    {
       rtx sym = XEXP (rtl, 0);
       tree type = TREE_TYPE (decl);
@@ -9616,7 +9649,8 @@ avr_encode_section_info (tree decl, rtx rtl, int new_decl_p)
       /* PSTR strings are in generic space but located in flash:
          patch address space.  */
 
-      if (-1 == avr_progmem_p (decl, attr))
+      if (!AVR_TINY
+          && -1 == avr_progmem_p (decl, attr))
         as = ADDR_SPACE_FLASH;
 
       AVR_SYMBOL_SET_ADDR_SPACE (sym, as);
@@ -9647,6 +9681,19 @@ avr_encode_section_info (tree decl, rtx rtl, int new_decl_p)
       if (addr_attr && !DECL_EXTERNAL (decl))
 	SYMBOL_REF_FLAGS (sym) |= SYMBOL_FLAG_ADDRESS;
     }
+
+  if (AVR_TINY
+      && decl
+      && VAR_DECL == TREE_CODE (decl)
+      && -1 == avr_progmem_p (decl, DECL_ATTRIBUTES (decl))
+      && MEM_P (rtl)
+      && SYMBOL_REF_P (XEXP (rtl, 0)))
+    {
+      /* Tag symbols for later addition of 0x4000 (AVR_TINY_PM_OFFSET).  */
+
+      rtx sym = XEXP (rtl, 0);
+      SYMBOL_REF_FLAGS (sym) |= AVR_SYMBOL_FLAG_TINY_PM;
+    }
 }
 
 

gcc/config/avr/avr.h

@@ -74,6 +74,8 @@ enum
                         || avr_arch->have_rampd)
 #define AVR_HAVE_EIJMP_EICALL (avr_arch->have_eijmp_eicall)
 
+#define AVR_TINY_PM_OFFSET (0x4000)
+
 /* Handling of 8-bit SP versus 16-bit SP is as follows:
 
 FIXME: DRIVER_SELF_SPECS has changed.

gcc/doc/extend.texi

@@ -1422,6 +1422,11 @@ const __memx void *pfoo = &foo;
 Such code requires at least binutils 2.23, see
 @w{@uref{http://sourceware.org/PR13503,PR13503}}.
 
+@item
+On the reduced Tiny devices like ATtiny40, no address spaces are supported.
+Data can be put into and read from flash memory by means of
+attribute @code{progmem}, see @ref{AVR Variable Attributes}.
+
 @end itemize
 
 @subsection M32C Named Address Spaces
@@ -5847,10 +5852,12 @@ attribute accomplishes this by putting respective variables into a
 section whose name starts with @code{.progmem}.
 
 This attribute works similar to the @code{section} attribute
-but adds additional checking. Notice that just like the
-@code{section} attribute, @code{progmem} affects the location
-of the data but not how this data is accessed.
+but adds additional checking.
 
+@table @asis
+@item @bullet{}@tie{} Ordinary AVR cores with 32 general purpose registers:
+@code{progmem} affects the location
+of the data but not how this data is accessed.
 In order to read data located with the @code{progmem} attribute
 (inline) assembler must be used.
 @smallexample
@@ -5873,6 +5880,28 @@ normally resides in the data memory (RAM).
 See also the @ref{AVR Named Address Spaces} section for
 an alternate way to locate and access data in flash memory.
 
+@item @bullet{}@tie{}Reduced AVR Tiny cores like ATtiny40:
+The compiler adds @code{0x4000}
+to the addresses of objects and declarations in @code{progmem} and locates
+the objects in flash memory, namely in section @code{.progmem.data}.
+The offset is needed because the flash memory is visible in the RAM
+address space starting at address @code{0x4000}.
+
+Data in @code{progmem} can be accessed by means of ordinary C@tie{}code,
+no special functions or macros are needed.
+
+@smallexample
+/* var is located in flash memory */
+extern const int var[2] __attribute__((progmem));
+
+int read_var (int i)
+@{
+    return var[i];
+@}
+@end smallexample
+
+@end table
+
 @item io
 @itemx io (@var{addr})
 @cindex @code{io} variable attribute, AVR

gcc/testsuite/ChangeLog

+2016-07-20  Georg-Johann Lay  <avr@gjlay.de>
+
+	PR target/71948
+	* gcc.target/avr/torture/tiny-progmem.c: New test.
+
 2016-07-20  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/71909

gcc/testsuite/gcc.target/avr/torture/tiny-progmem.c

+/* { dg-do run } */
+/* { dg-options "-Wl,--defsym,test6_xdata=0" } */
+
+#ifdef __AVR_TINY__
+#define PM __attribute__((__progmem__))
+#else
+/* On general core, just resort to vanilla C. */
+#define PM /* Empty */
+#endif
+
+#define PSTR(s) (__extension__({ static const char __c[] PM = (s); &__c[0];}))
+
+#define NI __attribute__((noinline,noclone))
+
+const volatile int data[] PM = { 1234, 5678 };
+const volatile int * volatile pdata = &data[1];
+
+int ram[2];
+
+const int myvar PM = 42;
+extern const int xvar __asm ("myvar") PM;
+
+NI int const volatile* get_addr_1 (void)
+{
+  return &data[1];
+}
+
+NI int const volatile* get_addr_x (int x)
+{
+  return &data[x];
+}
+
+void test_1 (void)
+{
+  if (data[0] != 1234)
+    __builtin_abort();
+
+  if (data[1] != 5678)
+    __builtin_abort();
+}
+
+void test_2 (void)
+{
+  if (data[1] != 5678)
+    __builtin_abort();
+}
+
+void test_3 (void)
+{
+  if (&data[1] != pdata)
+    __builtin_abort();
+}
+
+void test_4 (void)
+{
+  if (5678 != *get_addr_1())
+    __builtin_abort();
+  if (5678 != *get_addr_x(1))
+    __builtin_abort();
+}
+
+void test_5 (void)
+{
+  __builtin_memcpy (&ram, (void*) &data, 4);
+  if (ram[0] - ram[1] != 1234 - 5678)
+    __builtin_abort();
+}
+
+const char pmSTR[] PM = "01234";
+
+NI const char* get_pmSTR (int i)
+{
+  return pmSTR + 2 + i;
+}
+
+void test_6 (void)
+{
+#ifdef __AVR_TINY__
+  extern const int test6_xdata PM;
+  const char* str = PSTR ("Hallo");
+  if (0 == (__AVR_TINY_PM_BASE_ADDRESS__ & (__UINTPTR_TYPE__) str))
+    __builtin_abort();
+  if (0 == (__AVR_TINY_PM_BASE_ADDRESS__ & (__UINTPTR_TYPE__) test6_xdata))
+    __builtin_abort();
+#endif
+  
+  if (get_pmSTR (0)[0] != '0' + 2)
+    __builtin_abort();
+  if (get_pmSTR (1)[0] != '1' + 2)
+    __builtin_abort();
+}
+
+void test_7 (void)
+{
+  if (xvar != 42)
+    __builtin_abort();
+}
+
+int main()
+{
+  test_1();
+  test_2();
+  test_3();
+  test_4();
+  test_5();
+  test_6();
+  test_7();
+  return 0;
+}