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| author | Luc Van Oostenryck <luc.vanoostenryck@gmail.com> | 2020-11-01 23:29:30 +0100 |
|---|---|---|
| committer | Luc Van Oostenryck <luc.vanoostenryck@gmail.com> | 2020-11-08 02:16:21 +0100 |
| commit | 74d99ae4bd80d6b2064ca539ba4dffe24aaec362 (patch) | |
| tree | 8875b9c9482be8d797d5a0d493dc2c2586e47f9f | |
| parent | 4a5f616407e26efb67013f8267adef2d6e093bf1 (diff) | |
| download | sparse-dev-74d99ae4bd80d6b2064ca539ba4dffe24aaec362.tar.gz | |
cmp: simplify zext(x) cmps C
A signed compare of a zero-extended value against a constant
outside of the original range is statically known.
Simplify to the corresponding 0/1.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
| -rw-r--r-- | simplify.c | 14 | ||||
| -rw-r--r-- | validation/optim/cmp-zext-simm.c | 1 |
2 files changed, 14 insertions, 1 deletions
@@ -1185,6 +1185,20 @@ static int simplify_compare_constant(struct instruction *insn, long long value) insn->itype = def->orig_type; return replace_pseudo(insn, &insn->src1, def->src); } + switch (insn->opcode) { + case OP_SET_LT: case OP_SET_LE: + if (sign_extend(value, def->size) > (long long)bits) + return replace_with_value(insn, 1); + else + return replace_with_value(insn, 0); + break; + case OP_SET_GE: case OP_SET_GT: + if (sign_extend(value, def->size) > (long long)bits) + return replace_with_value(insn, 0); + else + return replace_with_value(insn, 1); + break; + } break; } return changed; diff --git a/validation/optim/cmp-zext-simm.c b/validation/optim/cmp-zext-simm.c index f89f8f8b..dda237d7 100644 --- a/validation/optim/cmp-zext-simm.c +++ b/validation/optim/cmp-zext-simm.c @@ -17,7 +17,6 @@ int zext_lgt(unsigned int x) { return (ZEXT(x) > -1) == 1; } /* * check-name: cmp-zext-simm * check-command: test-linearize -Wno-decl $file - * check-known-to-fail * * check-output-ignore * check-output-returns: 1 |