llvm/test/Transforms/InstCombine/alloca-poison-size.ll

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
; RUN: opt < %s -passes=instcombine -S | FileCheck %s

; InstCombineLoadStoreAlloca replaced alloca uses with null when the
; alloca size was poison. This causes invalid IR:
;
;   call void @llvm.lifetime.start(ptr %i_)
;   becomes:
;   call void @llvm.lifetime.start(ptr null)
;
; According to the lifetime intrinsic spec, the argument must be either:
;   - A pointer to an alloca instruction, or
;   - A poison value.
;
; Since null is neither an alloca pointer nor poison, this transformation
; produced invalid IR.

define i32 @foo() {
; CHECK-LABEL: define i32 @foo() {
; CHECK-NEXT:  [[ENTRY:.*:]]
; CHECK-NEXT:    store i32 0, ptr poison, align 4
; CHECK-NEXT:    ret i32 0
;
entry:
  %i_ = alloca i32, i32 poison, align 4
  call void @llvm.lifetime.start(ptr %i_)
  store i32 0, ptr %i_, align 4
  ret i32 0
}