Add several more icmp simplifications. Transform signed comparisons

into unsigned ones when the operands are known to have the same
sign bit value.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70053 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 28 insertions, 0 deletions

diff --git a/test/Transforms/InstCombine/signed-comparison.ll b/test/Transforms/InstCombine/signed-comparison.ll
new file mode 100644
index 0000000000..fdf150f9c6
--- /dev/null
+++ b/test/Transforms/InstCombine/signed-comparison.ll
@@ -0,0 +1,28 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis > %t
+; RUN: not grep zext %t
+; RUN: not grep slt %t
+; RUN: grep {icmp ult} %t
+
+; Instcombine should convert the zext+slt into a simple ult.
+
+define void @foo(double* %p) nounwind {
+entry:
+	br label %bb
+
+bb:
+	%indvar = phi i64 [ 0, %entry ], [ %indvar.next, %bb ]
+	%t0 = and i64 %indvar, 65535
+	%t1 = getelementptr double* %p, i64 %t0
+	%t2 = load double* %t1, align 8
+	%t3 = mul double %t2, 2.2
+	store double %t3, double* %t1, align 8
+	%i.04 = trunc i64 %indvar to i16
+	%t4 = add i16 %i.04, 1
+	%t5 = zext i16 %t4 to i32
+	%t6 = icmp slt i32 %t5, 500
+	%indvar.next = add i64 %indvar, 1
+	br i1 %t6, label %bb, label %return
+
+return:
+	ret void
+}