This is specially usefull when A is in fact undefined.
Reported-by: Dibyendu Majumdar <mobile@xxxxxxxxxxxxxxx>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
simplify.c | 42 +++++++++++++++++++++-
validation/optim/store-load-bitfield.c | 66 ++++++++++++++++++++++++++++++++++
2 files changed, 107 insertions(+), 1 deletion(-)
create mode 100644 validation/optim/store-load-bitfield.c
diff --git a/simplify.c b/simplify.c
index 30961cf39..40d4f0068 100644
--- a/simplify.c
+++ b/simplify.c
@@ -501,6 +501,46 @@ static int simplify_seteq_setne(struct instruction *insn, long long value)
}
}
+static int simplify_and_or_mask(struct instruction *insn, pseudo_t and, pseudo_t other, unsigned long long mask)
+{
+ struct instruction *def = and->def;
+ pseudo_t old;
+
+ if (!constant(def->src2))
+ return 0;
+ if (def->src2->value & mask)
+ return 0;
+ old = insn->src1;
+ use_pseudo(insn, other, &insn->src1);
+ remove_usage(old, &insn->src1);
+ return REPEAT_CSE;
+}
+
+static int simplify_constant_mask(struct instruction *insn, unsigned long long mask)
+{
+ struct instruction *left;
+ pseudo_t src1, src2;
+
+ switch (def_opcode(insn->src1)) {
+ case OP_OR:
+ // Let's handle ((A & M') | B ) & M
+ // or (B | (A & M')) & M
+ // when M' & M == 0
+ left = insn->src1->def;
+ src1 = left->src1;
+ src2 = left->src2;
+ if (def_opcode(src1) == OP_AND)
+ return simplify_and_or_mask(insn, src1, src2, mask);
+ if (def_opcode(src2) == OP_AND)
+ return simplify_and_or_mask(insn, src2, src1, mask);
+ break;
+
+ default:
+ break;
+ }
+ return 0;
+}
+
static int simplify_constant_rightside(struct instruction *insn)
{
long long value = insn->src2->value;
@@ -545,7 +585,7 @@ static int simplify_constant_rightside(struct instruction *insn)
case OP_AND:
if (!value)
return replace_with_pseudo(insn, insn->src2);
- return 0;
+ return simplify_constant_mask(insn, value);
case OP_SET_NE:
case OP_SET_EQ:
diff --git a/validation/optim/store-load-bitfield.c b/validation/optim/store-load-bitfield.c
new file mode 100644
index 000000000..b74022602
--- /dev/null
+++ b/validation/optim/store-load-bitfield.c
@@ -0,0 +1,66 @@
+int ufoo(int a)
+{
+ struct u {
+ unsigned int :2;
+ unsigned int a:3;
+ } bf;
+
+ bf.a = a;
+ return bf.a;
+}
+
+int sfoo(int a)
+{
+ struct s {
+ signed int :2;
+ signed int a:3;
+ } bf;
+
+ bf.a = a;
+ return bf.a;
+}
+
+int xfoo(int a)
+{
+ struct x {
+ int :2;
+ int a:3; // unsigned !
+ } bf;
+
+ bf.a = a;
+ return bf.a;
+}
+
+
+/*
+ * check-name: optim store/load bitfields
+ * check-command: test-linearize -Wno-decl $file
+ *
+ * check-output-start
+ufoo:
+.L0:
+ <entry-point>
+ scast.3 %r2 <- (32) %arg1
+ and.32 %r9 <- %r2, $7
+ ret.32 %r9
+
+
+sfoo:
+.L2:
+ <entry-point>
+ scast.3 %r13 <- (32) %arg1
+ and.32 %r20 <- %r13, $7
+ scast.32 %r21 <- (3) %r20
+ ret.32 %r21
+
+
+xfoo:
+.L4:
+ <entry-point>
+ scast.3 %r24 <- (32) %arg1
+ and.32 %r31 <- %r24, $7
+ ret.32 %r31
+
+
+ * check-output-end
+ */
--
2.14.0
--
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
