A N-bit truncate is not much different than ANDing with
a N-bit mask and so the same simplifications can be done.
[It's especially the case with bitfields where the TRUNC+ZEXT
of unsigned bitfields is simplified into an OP_AND while for
signed bitfields the TRUNC+SEXT can't be transformed into a
simple mask operation].
Apply the same simplifications as done for ((x & M) | y) & $mask(N)
---
simplify.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/simplify.c b/simplify.c
index baea32378..1569b4104 100644
--- a/simplify.c
+++ b/simplify.c
@@ -1238,6 +1238,7 @@ static int simplify_cast(struct instruction *insn)
struct instruction *def;
pseudo_t src;
pseudo_t val;
+ int rc = 0;
int osize;
int size;
@@ -1318,6 +1319,15 @@ static int simplify_cast(struct instruction *insn)
return replace_pseudo(insn, &insn->src1, def->src1);
}
break;
+ case OP_OR:
+ switch (insn->opcode) {
+ case OP_TRUNC:
+ mask = bits_mask(insn->size);
+ rc |= simplify_and_or_mask(def->src1, mask);
+ rc |= simplify_and_or_mask(def->src2, mask);
+ return rc;
+ }
+ break;
case OP_TRUNC:
osize = def->orig_type->bit_size;
if (insn->opcode == OP_ZEXT && size == osize) {
--
2.18.0
--
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