In the mathematical sense, the result of a left-shift by an
amount bigger than the operand size equals zero.
Do the corresponding simplification.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
simplify.c | 2 ++
validation/optim/shift-big.c | 7 +++++++
2 files changed, 9 insertions(+)
diff --git a/simplify.c b/simplify.c
index 9b700abc8..3b8e22c54 100644
--- a/simplify.c
+++ b/simplify.c
@@ -557,6 +557,8 @@ static int simplify_shift(struct instruction *insn, pseudo_t pseudo, long long v
break;
case OP_LSR:
size = operand_size(insn, pseudo);
+ /* fall through */
+ case OP_SHL:
if (value >= size)
return replace_with_pseudo(insn, value_pseudo(0));
}
diff --git a/validation/optim/shift-big.c b/validation/optim/shift-big.c
index 3249854e2..da65c5cdb 100644
--- a/validation/optim/shift-big.c
+++ b/validation/optim/shift-big.c
@@ -3,6 +3,7 @@ typedef int s32;
static u32 lsr32(u32 a) { return a >> 32; }
static s32 asr32(s32 a) { return a >> 32; }
+static u32 shl32(u32 a) { return a << 32; }
/*
* check-name: optim/shift-big.c
@@ -23,5 +24,11 @@ asr32:
ret.32 %r5
+shl32:
+.L4:
+ <entry-point>
+ ret.32 $0
+
+
* check-output-end
*/
--
2.18.0
--
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