[PhaseOrdering] Add test case for PR45682

Ensures that the correct sequence of simplifycfg/instcombine/sroa reduce the IR to just a icmp+assume (which will be dropped in backend)

Author: RKSimon

llvm/test/Transforms/PhaseOrdering/pr45682.ll

@@ -0,0 +1,37 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -O3 -S < %s                    | FileCheck %s
+; RUN: opt -passes='default<O3>' -S < %s  | FileCheck %s
+
+define void @PR45682(i32 %x, i32 %y) {
+; CHECK-LABEL: @PR45682(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[Y:%.*]], 0
+; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
+; CHECK-NEXT:    ret void
+;
+entry:
+  %x.addr = alloca i32, align 4
+  %y.addr = alloca i32, align 4
+  store i32 %x, i32* %x.addr, align 4
+  store i32 %y, i32* %y.addr, align 4
+  %0 = load i32, i32* %y.addr, align 4
+  %cmp = icmp sgt i32 %0, 0
+  call void @llvm.assume(i1 %cmp)
+  %1 = load i32, i32* %y.addr, align 4
+  %2 = load i32, i32* %x.addr, align 4
+  %add = add nsw i32 %2, %1
+  store i32 %add, i32* %x.addr, align 4
+  %3 = load i32, i32* %x.addr, align 4
+  %cmp1 = icmp eq i32 %3, -2147483648
+  br i1 %cmp1, label %if.then, label %if.end
+
+if.then:
+  call void @v()
+  br label %if.end
+
+if.end:
+  ret void
+}
+
+declare void @v()
+declare void @llvm.assume(i1)