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| author | Richard Kenner <kenner@vlsi1.ultra.nyu.edu> | 2002-04-09 13:41:58 +0000 |
|---|---|---|
| committer | Richard Kenner <kenner@gcc.gnu.org> | 2002-04-09 09:41:58 -0400 |
| commit | 1ce7f3c2ab0b622ec93be5bc39c3d4efa7fbef5f (patch) | |
| tree | 14d76b2c26294fb26b13f27cfd4812966dd80bf0 /gcc/expr.c | |
| parent | dcf5a5dec81e8afe74a41dea213c0fccceb80cd7 (diff) | |
| download | gcc-1ce7f3c2ab0b622ec93be5bc39c3d4efa7fbef5f.zip gcc-1ce7f3c2ab0b622ec93be5bc39c3d4efa7fbef5f.tar.gz gcc-1ce7f3c2ab0b622ec93be5bc39c3d4efa7fbef5f.tar.bz2 | |
expr.c (is_aligning_offset): New function.
* expr.c (is_aligning_offset): New function.
(expand_expr, case COMPONENT_EXPR): Call it.
From-SVN: r52077
Diffstat (limited to 'gcc/expr.c')
| -rw-r--r-- | gcc/expr.c | 57 |
1 files changed, 57 insertions, 0 deletions
@@ -147,6 +147,7 @@ static rtx store_field PARAMS ((rtx, HOST_WIDE_INT, int)); static rtx var_rtx PARAMS ((tree)); static HOST_WIDE_INT highest_pow2_factor PARAMS ((tree)); +static int is_aligning_offset PARAMS ((tree, tree)); static rtx expand_increment PARAMS ((tree, int, int)); static void do_jump_by_parts_greater PARAMS ((tree, int, rtx, rtx)); static void do_jump_by_parts_equality PARAMS ((tree, rtx, rtx)); @@ -6927,6 +6928,12 @@ expand_expr (exp, target, tmode, modifier) highest_pow2_factor (offset)); } + /* If OFFSET is making OP0 more aligned than BIGGEST_ALIGNMENT, + record its alignment as BIGGEST_ALIGNMENT. */ + if (GET_CODE (op0) == MEM && bitpos == 0 && offset != 0 + && is_aligning_offset (offset, tem)) + set_mem_align (op0, BIGGEST_ALIGNMENT); + /* Don't forget about volatility even if this is a bitfield. */ if (GET_CODE (op0) == MEM && volatilep && ! MEM_VOLATILE_P (op0)) { @@ -8823,6 +8830,56 @@ expand_expr (exp, target, tmode, modifier) return temp; } +/* Subroutine of above: returns 1 if OFFSET corresponds to an offset that + when applied to the address of EXP produces an address known to be + aligned more than BIGGEST_ALIGNMENT. */ + +static int +is_aligning_offset (offset, exp) + tree offset; + tree exp; +{ + /* Strip off any conversions and WITH_RECORD_EXPR nodes. */ + while (TREE_CODE (offset) == NON_LVALUE_EXPR + || TREE_CODE (offset) == NOP_EXPR + || TREE_CODE (offset) == CONVERT_EXPR + || TREE_CODE (offset) == WITH_RECORD_EXPR) + offset = TREE_OPERAND (offset, 0); + + /* We must now have a BIT_AND_EXPR with a constant that is one less than + power of 2 and which is larger than BIGGEST_ALIGNMENT. */ + if (TREE_CODE (offset) != BIT_AND_EXPR + || !host_integerp (TREE_OPERAND (offset, 1), 1) + || compare_tree_int (TREE_OPERAND (offset, 1), BIGGEST_ALIGNMENT) <= 0 + || !exact_log2 (tree_low_cst (TREE_OPERAND (offset, 1), 1) + 1) < 0) + return 0; + + /* Look at the first operand of BIT_AND_EXPR and strip any conversion. + It must be NEGATE_EXPR. Then strip any more conversions. */ + offset = TREE_OPERAND (offset, 0); + while (TREE_CODE (offset) == NON_LVALUE_EXPR + || TREE_CODE (offset) == NOP_EXPR + || TREE_CODE (offset) == CONVERT_EXPR) + offset = TREE_OPERAND (offset, 0); + + if (TREE_CODE (offset) != NEGATE_EXPR) + return 0; + + offset = TREE_OPERAND (offset, 0); + while (TREE_CODE (offset) == NON_LVALUE_EXPR + || TREE_CODE (offset) == NOP_EXPR + || TREE_CODE (offset) == CONVERT_EXPR) + offset = TREE_OPERAND (offset, 0); + + /* This must now be the address either of EXP or of a PLACEHOLDER_EXPR + whose type is the same as EXP. */ + return (TREE_CODE (offset) == ADDR_EXPR + && (TREE_OPERAND (offset, 0) == exp + || (TREE_CODE (TREE_OPERAND (offset, 0)) == PLACEHOLDER_EXPR + && (TREE_TYPE (TREE_OPERAND (offset, 0)) + == TREE_TYPE (exp))))); +} + /* Return the tree node if a ARG corresponds to a string constant or zero if it doesn't. If we return non-zero, set *PTR_OFFSET to the offset in bytes within the string that ARG is accessing. The type of the |