This transformation is especially usefull when simplifying code accessing bitfields or for other masking manipulations. Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx> --- simplify.c | 11 +++++++++++ validation/optim/shift-zext.c | 1 - validation/optim/shl-lsr.c | 1 - validation/optim/store-load-bitfield.c | 12 +++--------- 4 files changed, 14 insertions(+), 11 deletions(-) diff --git a/simplify.c b/simplify.c index 7f02d4742..acb834439 100644 --- a/simplify.c +++ b/simplify.c @@ -656,6 +656,17 @@ static int simplify_shift(struct instruction *insn, pseudo_t pseudo, long long v if (def_opcode(src) == OP_AND) return simplify_or_lsr(insn, src, def->src1, value); break; + case OP_SHL: + // replace (A << S) >> S + // by A & (Mask(size) >> S) + if (!constant(def->src2)) + break; + if (def->src2->value != value) + break; + size = insn->size - value; + insn->opcode = OP_AND; + insn->src2 = value_pseudo((1ULL << size) - 1); + return replace_pseudo(insn, &insn->src1, def->src1); } break; case OP_SHL: diff --git a/validation/optim/shift-zext.c b/validation/optim/shift-zext.c index 070416f30..30409beca 100644 --- a/validation/optim/shift-zext.c +++ b/validation/optim/shift-zext.c @@ -6,7 +6,6 @@ unsigned int foo(unsigned int x) /* * check-name: shift-zext * check-command: test-linearize -Wno-decl $file - * check-known-to-fail * * check-output-ignore * check-output-contains: and\\..*%arg1, \\$0xfff diff --git a/validation/optim/shl-lsr.c b/validation/optim/shl-lsr.c index 1ab2c48fc..4f4b7e66b 100644 --- a/validation/optim/shl-lsr.c +++ b/validation/optim/shl-lsr.c @@ -6,7 +6,6 @@ unsigned mask(unsigned x) /* * check-name: shl-lsr * check-command: test-linearize -Wno-decl $file - * check-known-to-fail * * check-output-ignore * check-output-contains: and\\..*0x1ffff diff --git a/validation/optim/store-load-bitfield.c b/validation/optim/store-load-bitfield.c index 1d8ff2402..f68cb6000 100644 --- a/validation/optim/store-load-bitfield.c +++ b/validation/optim/store-load-bitfield.c @@ -28,21 +28,15 @@ int sfoo(int a) ufoo: .L0: <entry-point> - and.32 %r4 <- %arg1, $7 - shl.32 %r5 <- %r4, $2 - lsr.32 %r9 <- %r5, $2 - and.32 %r11 <- %r9, $7 + and.32 %r11 <- %arg1, $7 ret.32 %r11 sfoo: .L2: <entry-point> - and.32 %r16 <- %arg1, $7 - shl.32 %r17 <- %r16, $2 - lsr.32 %r21 <- %r17, $2 - trunc.3 %r22 <- (32) %r21 - sext.32 %r23 <- (3) %r22 + trunc.3 %r16 <- (32) %arg1 + sext.32 %r23 <- (3) %r16 ret.32 %r23 -- 2.18.0 -- To unsubscribe from this list: send the line "unsubscribe linux-sparse" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
