From: claziss <claz...@synopsys.com> The _Uncached type qualifier can be used to bypass the cache without resorting to declaring variables as volatile.
gcc/ 2017-07-12 Claudiu Zissulescu <claz...@synopsys.com> * config/arc/arc-protos.h (arc_is_uncached_mem_p): Function proto. * config/arc/arc.c (arc_handle_uncached_attribute): New function. (arc_attribute_table): Add 'uncached' attribute. (arc_print_operand): Print '.di' flag for uncached memory accesses. (arc_in_small_data_p): Do not consider for small data the uncached types. (arc_is_uncached_mem_p): New function. * config/arc/predicates.md (compact_store_memory_operand): Check for uncached memory accesses. (nonvol_nonimm_operand): Likewise. gcc/testsuite 2017-07-12 Claudiu Zissulescu <claz...@synopsys.com> * gcc.target/arc/uncached.c: New test. --- gcc/config/arc/arc-protos.h | 1 + gcc/config/arc/arc.c | 65 ++++++++++++++++++++++++++++++++- gcc/config/arc/predicates.md | 7 +++- gcc/testsuite/gcc.target/arc/uncached.c | 18 +++++++++ 4 files changed, 88 insertions(+), 3 deletions(-) create mode 100644 gcc/testsuite/gcc.target/arc/uncached.c diff --git a/gcc/config/arc/arc-protos.h b/gcc/config/arc/arc-protos.h index f8e7937..cc00730 100644 --- a/gcc/config/arc/arc-protos.h +++ b/gcc/config/arc/arc-protos.h @@ -47,6 +47,7 @@ extern void arc_expand_compare_and_swap (rtx *); extern bool compact_memory_operand_p (rtx, machine_mode, bool, bool); extern int arc_return_address_register (unsigned int); extern unsigned int arc_compute_function_type (struct function *); +extern bool arc_is_uncached_mem_p (rtx); #endif /* RTX_CODE */ extern unsigned int arc_compute_frame_size (int); diff --git a/gcc/config/arc/arc.c b/gcc/config/arc/arc.c index 07dd072..a397cbd 100644 --- a/gcc/config/arc/arc.c +++ b/gcc/config/arc/arc.c @@ -222,7 +222,7 @@ static tree arc_handle_interrupt_attribute (tree *, tree, tree, int, bool *); static tree arc_handle_fndecl_attribute (tree *, tree, tree, int, bool *); static tree arc_handle_jli_attribute (tree *, tree, tree, int, bool *); static tree arc_handle_secure_attribute (tree *, tree, tree, int, bool *); - +static tree arc_handle_uncached_attribute (tree *, tree, tree, int, bool *); /* Initialized arc_attribute_table to NULL since arc doesnot have any machine specific supported attributes. */ @@ -254,6 +254,9 @@ const struct attribute_spec arc_attribute_table[] = /* Call a function using secure-mode. */ { "secure_call", 1, 1, false, true, true, arc_handle_secure_attribute, false }, + /* Bypass caches using .di flag. */ + { "uncached", 0, 0, false, true, false, arc_handle_uncached_attribute, + false }, { NULL, 0, 0, false, false, false, NULL, false } }; static int arc_comp_type_attributes (const_tree, const_tree); @@ -4135,7 +4138,8 @@ arc_print_operand (FILE *file, rtx x, int code) refs are defined to use the cache bypass mechanism. */ if (GET_CODE (x) == MEM) { - if (MEM_VOLATILE_P (x) && !TARGET_VOLATILE_CACHE_SET ) + if ((MEM_VOLATILE_P (x) && !TARGET_VOLATILE_CACHE_SET) + || arc_is_uncached_mem_p (x)) fputs (".di", file); } else @@ -8038,6 +8042,7 @@ static bool arc_in_small_data_p (const_tree decl) { HOST_WIDE_INT size; + tree attr; /* Only variables are going into small data area. */ if (TREE_CODE (decl) != VAR_DECL) @@ -8061,6 +8066,11 @@ arc_in_small_data_p (const_tree decl) && TREE_THIS_VOLATILE (decl)) return false; + /* Likewise for uncached data. */ + attr = TYPE_ATTRIBUTES (TREE_TYPE (decl)); + if (lookup_attribute ("uncached", attr)) + return false; + if (DECL_SECTION_NAME (decl) != 0) { const char *name = DECL_SECTION_NAME (decl); @@ -11066,6 +11076,57 @@ arc_is_secure_call_p (rtx pat) return false; } +/* Handle "uncached" qualifier. */ + +static tree +arc_handle_uncached_attribute (tree *node, + tree name, tree args, + int flags ATTRIBUTE_UNUSED, + bool *no_add_attrs) +{ + if (DECL_P (*node) && TREE_CODE (*node) != TYPE_DECL) + { + error ("%qE attribute only applies to types", + name); + *no_add_attrs = true; + } + else if (args) + { + warning (OPT_Wattributes, "argument of %qE attribute ignored", name); + } + return NULL_TREE; +} + +/* Return TRUE if PAT is a memory addressing an uncached data. */ + +bool +arc_is_uncached_mem_p (rtx pat) +{ + tree attrs; + tree ttype; + struct mem_attrs *refattrs; + + if (!MEM_P (pat)) + return false; + + /* Get the memory attributes. */ + refattrs = MEM_ATTRS (pat); + if (!refattrs + || !refattrs->expr) + return false; + + /* Get the type declaration. */ + ttype = TREE_TYPE (refattrs->expr); + if (!ttype) + return false; + + /* Get the type attributes. */ + attrs = TYPE_ATTRIBUTES (ttype); + if (lookup_attribute ("uncached", attrs)) + return true; + return false; +} + /* Implement TARGET_USE_ANCHORS_FOR_SYMBOL_P. We don't want to use anchors for small data: the GP register acts as an anchor in that case. We also don't want to use them for PC-relative accesses, diff --git a/gcc/config/arc/predicates.md b/gcc/config/arc/predicates.md index 3dfe0ca..68887be 100644 --- a/gcc/config/arc/predicates.md +++ b/gcc/config/arc/predicates.md @@ -217,6 +217,10 @@ if (MEM_VOLATILE_P (op) && !TARGET_VOLATILE_CACHE_SET) return 0; + /* likewise for uncached types. */ + if (arc_is_uncached_mem_p (op)) + return 0; + size = GET_MODE_SIZE (mode); /* dword operations really put out 2 instructions, so eliminate them. */ @@ -412,7 +416,8 @@ ;; and only the standard movXX patterns are set up to handle them. (define_predicate "nonvol_nonimm_operand" (and (match_code "subreg, reg, mem") - (match_test "(GET_CODE (op) != MEM || !MEM_VOLATILE_P (op)) && nonimmediate_operand (op, mode)")) + (match_test "(GET_CODE (op) != MEM || !MEM_VOLATILE_P (op)) && nonimmediate_operand (op, mode)") + (match_test "!arc_is_uncached_mem_p (op)")) ) ;; Return 1 if OP is a comparison operator valid for the mode of CC. diff --git a/gcc/testsuite/gcc.target/arc/uncached.c b/gcc/testsuite/gcc.target/arc/uncached.c new file mode 100644 index 0000000..367e8dc --- /dev/null +++ b/gcc/testsuite/gcc.target/arc/uncached.c @@ -0,0 +1,18 @@ +/* { dg-do compile } */ + +/* Check 'uncached' type attribute. */ + +typedef volatile unsigned int RwReg __attribute__ ((uncached)); + +typedef struct { + RwReg UART_THR; + int SIDE_DISH; +} UART; + +void uart_putc(UART *port, char c) +{ + port->UART_THR = c; + port->SIDE_DISH = c; +} + +/* { dg-final { scan-assembler-times "st\.di" 1 } } */ -- 1.9.1