A logical shift right followed by a sign extension is equivalent
to an arithmetic shift. Teach this to sparse.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
simplify.c | 13 ++++++++++++-
validation/optim/lsr-to-asr.c | 27 +++++++++++++++++++++++++++
2 files changed, 39 insertions(+), 1 deletion(-)
create mode 100644 validation/optim/lsr-to-asr.c
diff --git a/simplify.c b/simplify.c
index 1e7648486c49..3d398292f172 100644
--- a/simplify.c
+++ b/simplify.c
@@ -2066,7 +2066,7 @@ static int simplify_memop(struct instruction *insn)
static int simplify_cast(struct instruction *insn)
{
unsigned long long mask;
- struct instruction *def;
+ struct instruction *def, *def2;
pseudo_t src = insn->src;
pseudo_t val;
int osize;
@@ -2163,6 +2163,17 @@ static int simplify_cast(struct instruction *insn)
case OP_TRUNC:
insn->orig_type = def->orig_type;
return replace_pseudo(insn, &insn->src1, def->src);
+ case OP_SEXT:
+ if (size != def->orig_type->bit_size)
+ break;
+ if (DEF_OPCODE(def2, def->src) != OP_LSR)
+ break;
+ if (def2->src2 != value_pseudo(size - def->size))
+ break;
+ // SEXT(TRUNC(LSR(x, N))) --> ASR(x, N)
+ insn->opcode = OP_ASR;
+ insn->src2 = def2->src2;
+ return replace_pseudo(insn, &insn->src1, def2->src1);
case OP_ZEXT:
if (size != def->orig_type->bit_size)
break;
diff --git a/validation/optim/lsr-to-asr.c b/validation/optim/lsr-to-asr.c
new file mode 100644
index 000000000000..269277396429
--- /dev/null
+++ b/validation/optim/lsr-to-asr.c
@@ -0,0 +1,27 @@
+int lsr_to_asr24(int x)
+{
+ return ((signed char)(((unsigned)x) >> 24)) == (x >> 24);
+}
+
+
+struct s {
+ int :30;
+ signed int f:2;
+};
+
+int lsr_to_asr30(int a)
+{
+ union {
+ int i;
+ struct s s;
+ } u = { .i = a };
+ return u.s.f == (a >> 30);
+}
+
+/*
+ * check-name: lsr-to-asr
+ * check-command: test-linearize -Wno-decl $file
+ *
+ * check-output-ignore
+ * check-output-returns: 1
+ */
--
2.30.0
