Imported Upstream version 5.18.0.205

Former-commit-id: 7f59f7e792705db773f1caecdaa823092f4e2927

external/llvm/test/CodeGen/ARM/dag-combine-ldst.ll

@@ -0,0 +1,41 @@
+; RUN: llc < %s -mtriple=arm-eabi -mattr=+v4t -O0 | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK_O0
+; RUN: llc < %s -mtriple=arm-eabi -mattr=+v4t -O1 | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK_O1
+
+; In /O0, the addition must not be eliminated. This happens when the load
+; and store are folded by the DAGCombiner. In /O1 and above, the optimization
+; must be executed.
+
+; CHECK-LABEL:   {{^}}main
+; CHECK:         mov [[TMP:r[0-9]+]], #0
+; CHECK-NEXT:    str [[TMP]], [sp, #4]
+; CHECK_O0:      str [[TMP]], [sp]
+; CHECK_O0:      ldr [[TMP:r[0-9]+]], [sp]
+; CHECK_O0-NEXT: add [[TMP]], [[TMP]], #2
+; CHECK_O1-NOT:  ldr [[TMP:r[0-9]+]], [sp]
+; CHECK_O1-NOT:  add [[TMP]], [[TMP]], #2
+
+define i32 @main() {
+bb:
+  %tmp = alloca i32, align 4
+  %tmp1 = alloca i32, align 4
+  store i32 0, i32* %tmp, align 4
+  store i32 0, i32* %tmp1, align 4
+  %tmp2 = load i32, i32* %tmp1, align 4
+  %tmp3 = add nsw i32 %tmp2, 2
+  store i32 %tmp3, i32* %tmp1, align 4
+  %tmp4 = load i32, i32* %tmp1, align 4
+  %tmp5 = icmp eq i32 %tmp4, 2
+  br i1 %tmp5, label %bb6, label %bb7
+
+bb6:                                              ; preds = %bb
+  store i32 0, i32* %tmp, align 4
+  br label %bb8
+
+bb7:                                              ; preds = %bb
+  store i32 5, i32* %tmp, align 4
+  br label %bb8
+
+bb8:                                              ; preds = %bb7, %bb6
+  %tmp9 = load i32, i32* %tmp, align 4
+  ret i32 %tmp9
+}