1 files changed, 36 insertions, 0 deletions
diff --git a/llvm/test/CodeGen/ARM/ldrex-frame-size.ll b/llvm/test/CodeGen/ARM/ldrex-frame-size.ll
new file mode 100644
index 00000000000..595540578a0
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/ldrex-frame-size.ll
@@ -0,0 +1,36 @@
+; RUN: llc -mtriple=thumbv7-linux-gnueabi -o - %s | FileCheck %s
+
+; This alloca is just large enough that FrameLowering decides it needs a frame
+; to guarantee access, based on the range of ldrex.
+
+; The actual alloca size is a bit of black magic, unfortunately: the real
+; maximum accessible is 1020, but FrameLowering adds 16 bytes to its estimated
+; stack size just because so the alloca is not actually the what the limit gets
+; compared to. The important point is that we don't go up to ~4096, which is the
+; default with no strange instructions.
+define void @test_large_frame() {
+; CHECK-LABEL: test_large_frame:
+; CHECK: push
+; CHECK: sub.w sp, sp, #1004
+
+  %ptr = alloca i32, i32 251
+
+  %addr = getelementptr i32, i32* %ptr, i32 1
+  call i32 @llvm.arm.ldrex.p0i32(i32* %addr)
+  ret void
+}
+
+; This alloca is just is just the other side of the limit, so no frame
+define void @test_small_frame() {
+; CHECK-LABEL: test_small_frame:
+; CHECK-NOT: push
+; CHECK: sub.w sp, sp, #1000
+
+  %ptr = alloca i32, i32 250
+
+  %addr = getelementptr i32, i32* %ptr, i32 1
+  call i32 @llvm.arm.ldrex.p0i32(i32* %addr)
+  ret void
+}
+
+declare i32 @llvm.arm.ldrex.p0i32(i32*)