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| author | Luc Van Oostenryck <luc.vanoostenryck@gmail.com> | 2018-08-23 09:47:51 +0200 |
|---|---|---|
| committer | Luc Van Oostenryck <luc.vanoostenryck@gmail.com> | 2018-08-23 10:04:20 +0200 |
| commit | f8f80ee849cd58c274ceade48a832d237aaf96e2 (patch) | |
| tree | c009e0f66d00ceec7149d241f87e45e0410f669f | |
| parent | a4ae84a892b6e5a8b563f0bb125fcc5a3448b383 (diff) | |
| download | sparse-dev-f8f80ee849cd58c274ceade48a832d237aaf96e2.tar.gz | |
doc: extend simplification notation
Add the description for MASK(x, M) & SHIFT(x, S).
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
| -rw-r--r-- | simplify.c | 28 |
1 files changed, 15 insertions, 13 deletions
@@ -30,7 +30,14 @@ // * `TRUNC(x, N)` is used for a truncation *to* a size of `N` bits // * `ZEXT(x, N)` is used for a zero-extension *from* a size of `N` bits // * `OP(x, C)` is used to represent some generic operation using a constant, -// including `TRUNC(x, N)` and `ZEXT(x, N)`. +// including when the constant is implicit (e.g. `TRUNC(x, N)`). +// * `MASK(x, M)` is used to respresent a 'masking' instruction: +// - `AND(x, M)` +// - `LSR(x, S)`, with `M` = (-1 << S) +// - `SHL(x, S)`, with `M` = (-1 >> S) +// - `TRUNC(x, N)`, with `M` = $mask(N) +// - `ZEXT(x, N)`, with `M` = $mask(N) +// * `SHIFT(x, S)` is used for `LSR(x, S)` or `SHL(x, S)`. #include <assert.h> @@ -582,9 +589,9 @@ undef: // ^^^^^^^^^^^^^^^ /// -// try to simplify OP(OR(AND(x, M'), b), K) -// @insn: the 'masking' instruction -// @mask: the mask associated to @insn (M) +// try to simplify MASK(OR(AND(x, M'), b), M) +// @insn: the masking instruction +// @mask: the associated mask (M) // @ora: one of the OR's operands, guaranteed to be PSEUDO_REG // @orb: the other OR's operand // @return: 0 if no changes have been made, one or more REPEAT_* flags otherwise. @@ -622,16 +629,11 @@ static int simplify_mask_or_and(struct instruction *insn, unsigned long long mas } /// -// try to simplify OP(OR(a, b), K) -// @insn: the 'masking' instruction -// @mask: the mask associated to @insn (M): +// try to simplify MASK(OR(a, b), M) +// @insn: the masking instruction +// @mask: the associated mask (M) // @or: the OR instruction // @return: 0 if no changes have been made, one or more REPEAT_* flags otherwise. -// -// For the @mask (M): -// * if OP(x, K) == AND(x, M), @mask M is K -// * if OP(x, K) == LSR(x, S), @mask M is (-1 << S) -// * if OP(x, K) == SHL(x, S), @mask M is (-1 >> S) static int simplify_mask_or(struct instruction *insn, unsigned long long mask, struct instruction *or) { pseudo_t src1 = or->src1; @@ -649,7 +651,7 @@ static int simplify_mask_or(struct instruction *insn, unsigned long long mask, s unsigned long long oval = src2->value; unsigned long long nval = oval & mask; // Try to simplify: - // OP(OR(x, C), K) + // MASK(OR(x, C), M) if (nval == 0) { // if (C & M) == 0: OR(x, C) -> x return replace_pseudo(insn, &insn->src1, src1); |