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

3 files changed, 54 insertions, 4 deletions

diff --git a/gcc/config/avr/avr-c.c b/gcc/config/avr/avr-c.c
index a338a9f..270b803 100644
--- a/gcc/config/avr/avr-c.c
+++ b/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)
diff --git a/gcc/config/avr/avr.c b/gcc/config/avr/avr.c
index 6553cd8..95f691c 100644
--- a/gcc/config/avr/avr.c
+++ b/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;
+    }
 }
 
 
diff --git a/gcc/config/avr/avr.h b/gcc/config/avr/avr.h
index ab5e465..5eb90b5 100644
--- a/gcc/config/avr/avr.h
+++ b/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.