[Hexagon] Handle subregisters when calculating iteration count in HW loops
llvm-svn: 329434
diff --git a/llvm/test/CodeGen/Hexagon/hwloop-subreg.ll b/llvm/test/CodeGen/Hexagon/hwloop-subreg.ll
new file mode 100644
index 0000000..602e1bd
--- /dev/null
+++ b/llvm/test/CodeGen/Hexagon/hwloop-subreg.ll
@@ -0,0 +1,30 @@
+; RUN: llc -march=hexagon < %s
+; REQUIRES: asserts
+
+target triple = "hexagon"
+
+; Function Attrs: nounwind optsize readonly
+define void @f0() #0 align 2 {
+b0:
+ %v0 = load i32, i32* undef, align 8
+ %v1 = zext i32 %v0 to i64
+ %v2 = add nuw nsw i64 %v1, 63
+ %v3 = lshr i64 %v2, 6
+ %v4 = trunc i64 %v3 to i32
+ br i1 undef, label %b3, label %b1
+
+b1: ; preds = %b0
+ %v5 = add nsw i32 %v4, -1
+ br label %b2
+
+b2: ; preds = %b2, %b1
+ %v6 = phi i32 [ %v5, %b1 ], [ %v7, %b2 ]
+ %v7 = add i32 %v6, -1
+ %v8 = icmp sgt i32 %v7, -1
+ br i1 %v8, label %b2, label %b3
+
+b3: ; preds = %b2, %b0
+ ret void
+}
+
+attributes #0 = { nounwind optsize readonly }