[TypePromotion] Introduce test for PR134281 (NFC)

Author: antoniofrighetto

llvm/test/CodeGen/AArch64/typepromotion-gep.ll

@@ -0,0 +1,44 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S -p typepromotion %s -o - | FileCheck %s
+
+target triple = "arm64-apple-macosx15.0.0"
+
+; FIXME: This is a miscompilation, unused trunc is converted to used zext for gep offset,
+; which is to be treated as signed.
+define i4 @gep_offset_signedness(ptr %ptr, i8 %offset, i1 %cond) {
+; CHECK-LABEL: define i4 @gep_offset_signedness(
+; CHECK-SAME: ptr [[PTR:%.*]], i8 [[OFFSET:%.*]], i1 [[COND:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[TMP0:%.*]] = zext i8 [[OFFSET]] to i32
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[TMP0]], 15
+; CHECK-NEXT:    [[PTR_IDX:%.*]] = getelementptr i8, ptr [[PTR]], i32 [[TMP0]]
+; CHECK-NEXT:    [[COND_2:%.*]] = icmp uge ptr [[PTR_IDX]], [[PTR]]
+; CHECK-NEXT:    br i1 [[COND_2]], label %[[RETURN:.*]], label %[[ELSE:.*]]
+; CHECK:       [[RETURN]]:
+; CHECK-NEXT:    [[RET_VAL:%.*]] = phi i4 [ 0, %[[ELSE_RET:.*]] ], [ 1, %[[ENTRY]] ], [ 0, %[[ELSE]] ]
+; CHECK-NEXT:    ret i4 [[RET_VAL]]
+; CHECK:       [[ELSE]]:
+; CHECK-NEXT:    [[ADD:%.*]] = add nuw i32 0, 0
+; CHECK-NEXT:    [[COND_3:%.*]] = icmp ult i32 [[ADD]], [[TMP0]]
+; CHECK-NEXT:    br i1 [[COND]], label %[[RETURN]], label %[[ELSE_RET]]
+; CHECK:       [[ELSE_RET]]:
+; CHECK-NEXT:    br label %[[RETURN]]
+;
+entry:
+  %unused_trunc = trunc i8 %offset to i4
+  %ptr.idx = getelementptr i8, ptr %ptr, i8 %offset
+  %cond.2 = icmp uge ptr %ptr.idx, %ptr
+  br i1 %cond.2, label %return, label %else
+
+return:                                              ; preds = %else.ret, %else, %entry
+  %ret.val = phi i4 [ 0, %else.ret ], [ 1, %entry ], [ 0, %else ]
+  ret i4 %ret.val
+
+else:                                                ; preds = %entry
+  %add = add nuw i8 0, 0
+  %cond.3 = icmp ult i8 %add, %offset
+  br i1 %cond, label %return, label %else.ret
+
+else.ret:                                            ; preds = %else
+  br label %return
+}