Expressions involving equality testing against zero are ubiquitious
and can often be simplified with previous comparisons.
For example, when using test-linearize on the following code:
_Bool foo(int a) { return !(a < 3); }
the following was emitted:
setlt.32 %r2 <- %arg1, $3
seteq.32 %r3 <- %r2, $0
setne.1 %r4 <- %r3, $0
ret.1 %r4
but this can be simplified into:
setge.1 %r4 <- %arg1, $3
ret.1 %r4
Implement this simplification and add associated test cases.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
simplify.c | 65 ++++++++++++++++++++++++++++++++++++++++++
validation/optim/setcc-setcc.c | 19 ++++++++++++
validation/optim/setcc-seteq.c | 13 +++++++++
validation/optim/setcc-setne.c | 13 +++++++++
4 files changed, 110 insertions(+)
create mode 100644 validation/optim/setcc-setcc.c
create mode 100644 validation/optim/setcc-seteq.c
create mode 100644 validation/optim/setcc-setne.c
diff --git a/simplify.c b/simplify.c
index b29b3ebb..d076ebb5 100644
--- a/simplify.c
+++ b/simplify.c
@@ -310,6 +310,67 @@ static int simplify_asr(struct instruction *insn, pseudo_t pseudo, long long val
return 0;
}
+static int compare_opcode(int opcode, int inverse)
+{
+ if (!inverse)
+ return opcode;
+
+ switch (opcode) {
+ case OP_SET_EQ: return OP_SET_NE;
+ case OP_SET_NE: return OP_SET_EQ;
+
+ case OP_SET_LT: return OP_SET_GE;
+ case OP_SET_LE: return OP_SET_GT;
+ case OP_SET_GT: return OP_SET_LE;
+ case OP_SET_GE: return OP_SET_LT;
+
+ case OP_SET_A: return OP_SET_BE;
+ case OP_SET_AE: return OP_SET_B;
+ case OP_SET_B: return OP_SET_AE;
+ case OP_SET_BE: return OP_SET_A;
+
+ default:
+ return opcode;
+ }
+}
+
+static int simplify_seteq_setne(struct instruction *insn, long long value)
+{
+ struct instruction *def = insn->src1->def;
+ pseudo_t src1, src2;
+ int inverse;
+ int opcode;
+
+ if (value != 0 && value != 1)
+ return 0;
+
+ if (!def)
+ return 0;
+
+ inverse = (insn->opcode == OP_SET_NE) == value;
+ opcode = def->opcode;
+ switch (opcode) {
+ case OP_BINCMP ... OP_BINCMP_END:
+ // Convert:
+ // setcc.n %t <- %a, %b
+ // setne.m %r <- %t, $0
+ // into:
+ // setcc.n %t <- %a, %b
+ // setcc.m %r <- %a, $b
+ // and similar for setne/eq ... 0/1
+ src1 = def->src1;
+ src2 = def->src2;
+ remove_usage(insn->src1, &insn->src1);
+ insn->opcode = compare_opcode(opcode, inverse);
+ use_pseudo(insn, src1, &insn->src1);
+ use_pseudo(insn, src2, &insn->src2);
+ return REPEAT_CSE;
+
+ default:
+ return 0;
+ }
+}
+
static int simplify_constant_rightside(struct instruction *insn)
{
long long value = insn->src2->value;
@@ -342,6 +403,10 @@ static int simplify_constant_rightside(struct instruction *insn)
if (!value)
return replace_with_pseudo(insn, insn->src2);
return 0;
+
+ case OP_SET_NE:
+ case OP_SET_EQ:
+ return simplify_seteq_setne(insn, value);
}
return 0;
}
diff --git a/validation/optim/setcc-setcc.c b/validation/optim/setcc-setcc.c
new file mode 100644
index 00000000..fac7520e
--- /dev/null
+++ b/validation/optim/setcc-setcc.c
@@ -0,0 +1,19 @@
+static _Bool blt(int a, int b) { return (a < b); }
+static _Bool bnge(int a, int b) { return !(a >= b); }
+static _Bool bgt(int a, int b) { return (a > b); }
+static _Bool bnle(int a, int b) { return !(a <= b); }
+static _Bool ble(int a, int b) { return (a <= b); }
+static _Bool bngt(int a, int b) { return !(a > b); }
+static _Bool bge(int a, int b) { return (a >= b); }
+static _Bool bnlt(int a, int b) { return !(a < b); }
+
+/*
+ * check-name: optim/setcc-setcc
+ * check-command: test-linearize $file
+ * check-output-ignore
+ *
+ * check-output-excludes: set..\\.32
+ * check-output-excludes: setne\\.1
+ * check-output-excludes: seteq\\.1
+ * check-output-contains: set[gt][te]\\.1
+ */
diff --git a/validation/optim/setcc-seteq.c b/validation/optim/setcc-seteq.c
new file mode 100644
index 00000000..d8765fe1
--- /dev/null
+++ b/validation/optim/setcc-seteq.c
@@ -0,0 +1,13 @@
+static _Bool beq0(int a) { return (a == 0); }
+static _Bool bnotneq0(int a) { return !(a != 0); }
+static _Bool bnot(int a) { return !a; }
+
+/*
+ * check-name: optim/setcc-seteq
+ * check-command: test-linearize $file
+ * check-output-ignore
+ *
+ * check-output-excludes: set..\\.32
+ * check-output-excludes: setne\\.1
+ * check-output-contains: seteq\\.1
+ */
diff --git a/validation/optim/setcc-setne.c b/validation/optim/setcc-setne.c
new file mode 100644
index 00000000..f982eb34
--- /dev/null
+++ b/validation/optim/setcc-setne.c
@@ -0,0 +1,13 @@
+static _Bool bnoteq0(int a) { return !(a == 0); }
+static _Bool bne0(int a) { return (a != 0); }
+static _Bool bnotnot(int a) { return !!a; }
+
+/*
+ * check-name: optim/setcc-setne
+ * check-command: test-linearize $file
+ * check-output-ignore
+ *
+ * check-output-excludes: set..\\.32
+ * check-output-excludes: seteq\\.1
+ * check-output-contains: setne\\.1
+ */
--
2.10.2
--
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
