diff options
Diffstat (limited to 'gcc/emit-rtl.c')
| -rw-r--r-- | gcc/emit-rtl.c | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c index 0738f384497..830ce1dc910 100644 --- a/gcc/emit-rtl.c +++ b/gcc/emit-rtl.c @@ -1490,6 +1490,90 @@ mem_expr_equal_p (const_tree expr1, const_tree expr2) return 0; } +/* Return OFFSET if XEXP (MEM, 0) - OFFSET is known to be ALIGN + bits aligned for 0 <= OFFSET < ALIGN / BITS_PER_UNIT, or + -1 if not known. */ + +int +get_mem_align_offset (rtx mem, int align) +{ + tree expr; + unsigned HOST_WIDE_INT offset; + + /* This function can't use + if (!MEM_EXPR (mem) || !MEM_OFFSET (mem) + || !CONST_INT_P (MEM_OFFSET (mem)) + || (get_object_alignment (MEM_EXPR (mem), MEM_ALIGN (mem), align) + < align)) + return -1; + else + return (- INTVAL (MEM_OFFSET (mem))) & (align / BITS_PER_UNIT - 1); + for two reasons: + - COMPONENT_REFs in MEM_EXPR can have NULL first operand, + for <variable>. get_inner_reference doesn't handle it and + even if it did, the alignment in that case needs to be determined + from DECL_FIELD_CONTEXT's TYPE_ALIGN. + - it would do suboptimal job for COMPONENT_REFs, even if MEM_EXPR + isn't sufficiently aligned, the object it is in might be. */ + gcc_assert (MEM_P (mem)); + expr = MEM_EXPR (mem); + if (expr == NULL_TREE + || MEM_OFFSET (mem) == NULL_RTX + || !CONST_INT_P (MEM_OFFSET (mem))) + return -1; + + offset = INTVAL (MEM_OFFSET (mem)); + if (DECL_P (expr)) + { + if (DECL_ALIGN (expr) < align) + return -1; + } + else if (INDIRECT_REF_P (expr)) + { + if (TYPE_ALIGN (TREE_TYPE (expr)) < (unsigned int) align) + return -1; + } + else if (TREE_CODE (expr) == COMPONENT_REF) + { + while (1) + { + tree inner = TREE_OPERAND (expr, 0); + tree field = TREE_OPERAND (expr, 1); + tree byte_offset = component_ref_field_offset (expr); + tree bit_offset = DECL_FIELD_BIT_OFFSET (field); + + if (!byte_offset + || !host_integerp (byte_offset, 1) + || !host_integerp (bit_offset, 1)) + return -1; + + offset += tree_low_cst (byte_offset, 1); + offset += tree_low_cst (bit_offset, 1) / BITS_PER_UNIT; + + if (inner == NULL_TREE) + { + if (TYPE_ALIGN (DECL_FIELD_CONTEXT (field)) + < (unsigned int) align) + return -1; + break; + } + else if (DECL_P (inner)) + { + if (DECL_ALIGN (inner) < align) + return -1; + break; + } + else if (TREE_CODE (inner) != COMPONENT_REF) + return -1; + expr = inner; + } + } + else + return -1; + + return offset & ((align / BITS_PER_UNIT) - 1); +} + /* Given REF (a MEM) and T, either the type of X or the expression corresponding to REF, set the memory attributes. OBJECTP is nonzero if we are making a new object of this type. BITPOS is nonzero if |