test/Transforms/InstCombine/compare-alloca.ll

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -passes=instcombine -S %s | FileCheck %s
target datalayout = "p:32:32"


define i1 @alloca_argument_compare(ptr %arg) {
; CHECK-LABEL: @alloca_argument_compare(
; CHECK-NEXT:    ret i1 false
;
  %alloc = alloca i64
  %cmp = icmp eq ptr %arg, %alloc
  ret i1 %cmp
}

define i1 @alloca_argument_compare_swapped(ptr %arg) {
; CHECK-LABEL: @alloca_argument_compare_swapped(
; CHECK-NEXT:    ret i1 false
;
  %alloc = alloca i64
  %cmp = icmp eq ptr %alloc, %arg
  ret i1 %cmp
}

define i1 @alloca_argument_compare_ne(ptr %arg) {
; CHECK-LABEL: @alloca_argument_compare_ne(
; CHECK-NEXT:    ret i1 true
;
  %alloc = alloca i64
  %cmp = icmp ne ptr %arg, %alloc
  ret i1 %cmp
}

define i1 @alloca_argument_compare_derived_ptrs(ptr %arg, i64 %x) {
; CHECK-LABEL: @alloca_argument_compare_derived_ptrs(
; CHECK-NEXT:    ret i1 false
;
  %alloc = alloca i64, i64 8
  %p = getelementptr i64, ptr %arg, i64 %x
  %q = getelementptr i64, ptr %alloc, i64 3
  %cmp = icmp eq ptr %p, %q
  ret i1 %cmp
}

declare void @escape(ptr)
define i1 @alloca_argument_compare_escaped_alloca(ptr %arg) {
; CHECK-LABEL: @alloca_argument_compare_escaped_alloca(
; CHECK-NEXT:    [[ALLOC:%.*]] = alloca i64, align 8
; CHECK-NEXT:    call void @escape(ptr nonnull [[ALLOC]])
; CHECK-NEXT:    [[CMP:%.*]] = icmp eq ptr [[ALLOC]], [[ARG:%.*]]
; CHECK-NEXT:    ret i1 [[CMP]]
;
  %alloc = alloca i64
  call void @escape(ptr %alloc)
  %cmp = icmp eq ptr %alloc, %arg
  ret i1 %cmp
}

declare void @check_compares(i1, i1)
define void @alloca_argument_compare_two_compares(ptr %p) {
; CHECK-LABEL: @alloca_argument_compare_two_compares(
; CHECK-NEXT:    call void @check_compares(i1 false, i1 false)
; CHECK-NEXT:    ret void
;
  %q = alloca i64, i64 8
  %r = getelementptr i64, ptr %p, i64 1
  %s = getelementptr i64, ptr %q, i64 2
  %cmp1 = icmp eq ptr %p, %q
  %cmp2 = icmp eq ptr %r, %s
  call void @check_compares(i1 %cmp1, i1 %cmp2)
  ret void
  ; We will only fold if there is a single cmp.
}

define i1 @alloca_argument_compare_escaped_through_store(ptr %arg, ptr %ptr) {
; CHECK-LABEL: @alloca_argument_compare_escaped_through_store(
; CHECK-NEXT:    [[ALLOC:%.*]] = alloca i64, align 8
; CHECK-NEXT:    [[CMP:%.*]] = icmp eq ptr [[ALLOC]], [[ARG:%.*]]
; CHECK-NEXT:    [[P:%.*]] = getelementptr inbounds i64, ptr [[ALLOC]], i32 1
; CHECK-NEXT:    store ptr [[P]], ptr [[PTR:%.*]], align 4
; CHECK-NEXT:    ret i1 [[CMP]]
;
  %alloc = alloca i64
  %cmp = icmp eq ptr %alloc, %arg
  %p = getelementptr i64, ptr %alloc, i64 1
  store ptr %p, ptr %ptr
  ret i1 %cmp
}

declare void @llvm.lifetime.start.p0(i64, ptr nocapture)
declare void @llvm.lifetime.end.p0(i64, ptr nocapture)
define i1 @alloca_argument_compare_benign_instrs(ptr %arg) {
; CHECK-LABEL: @alloca_argument_compare_benign_instrs(
; CHECK-NEXT:    ret i1 false
;
  %alloc = alloca i8
  call void @llvm.lifetime.start.p0(i64 1, ptr %alloc)
  %cmp = icmp eq ptr %arg, %alloc
  %x = load i8, ptr %arg
  store i8 %x, ptr %alloc
  call void @llvm.lifetime.end.p0(i64 1, ptr %alloc)
  ret i1 %cmp
}

declare ptr @allocator()
define i1 @alloca_call_compare() {
; CHECK-LABEL: @alloca_call_compare(
; CHECK-NEXT:    [[Q:%.*]] = call ptr @allocator()
; CHECK-NEXT:    ret i1 false
;
  %p = alloca i64
  %q = call ptr @allocator()
  %cmp = icmp eq ptr %p, %q
  ret i1 %cmp
}


; The next block of tests demonstrate a very subtle correctness requirement.
; We can generally assume any *single* stack layout we chose for the result of
; an alloca, but we can't simultanious assume two different ones.  As a
; result, we must make sure that we only fold conditions if we can ensure that
; we fold *all* potentially address capturing compares the same.

; These two functions represents either a) forging a pointer via inttoptr or
; b) indexing off an adjacent allocation.  In either case, the operation is
; obscured by an uninlined helper and not visible to instcombine.
declare ptr @hidden_inttoptr()
declare ptr @hidden_offset(ptr %other)

define i1 @ptrtoint_single_cmp() {
; CHECK-LABEL: @ptrtoint_single_cmp(
; CHECK-NEXT:    ret i1 false
;
  %m = alloca i8, i32 4
  %rhs = inttoptr i64 2048 to ptr
  %cmp = icmp eq ptr %m, %rhs
  ret i1 %cmp
}

define i1 @offset_single_cmp() {
; CHECK-LABEL: @offset_single_cmp(
; CHECK-NEXT:    ret i1 false
;
  %m = alloca i8, i32 4
  %n = alloca i8, i32 4
  %rhs = getelementptr i8, ptr %n, i32 4
  %cmp = icmp eq ptr %m, %rhs
  ret i1 %cmp
}

declare void @witness(i1, i1)

define void @consistent_fold1() {
; CHECK-LABEL: @consistent_fold1(
; CHECK-NEXT:    [[RHS2:%.*]] = call ptr @hidden_inttoptr()
; CHECK-NEXT:    call void @witness(i1 false, i1 false)
; CHECK-NEXT:    ret void
;
  %m = alloca i8, i32 4
  %rhs = inttoptr i64 2048 to ptr
  %rhs2 = call ptr @hidden_inttoptr()
  %cmp1 = icmp eq ptr %m, %rhs
  %cmp2 = icmp eq ptr %m, %rhs2
  call void @witness(i1 %cmp1, i1 %cmp2)
  ret void
}

define void @consistent_fold2() {
; CHECK-LABEL: @consistent_fold2(
; CHECK-NEXT:    [[N2:%.*]] = alloca [4 x i8], align 1
; CHECK-NEXT:    [[RHS2:%.*]] = call ptr @hidden_offset(ptr nonnull [[N2]])
; CHECK-NEXT:    call void @witness(i1 false, i1 false)
; CHECK-NEXT:    ret void
;
  %m = alloca i8, i32 4
  %n = alloca i8, i32 4
  %rhs = getelementptr i8, ptr %n, i32 4
  %rhs2 = call ptr @hidden_offset(ptr %n)
  %cmp1 = icmp eq ptr %m, %rhs
  %cmp2 = icmp eq ptr %m, %rhs2
  call void @witness(i1 %cmp1, i1 %cmp2)
  ret void
}

define void @consistent_fold3() {
; CHECK-LABEL: @consistent_fold3(
; CHECK-NEXT:    [[RHS2:%.*]] = call ptr @hidden_inttoptr()
; CHECK-NEXT:    call void @witness(i1 false, i1 false)
; CHECK-NEXT:    ret void
;
  %m = alloca i8, i32 4
  %lgp = load ptr, ptr @gp, align 8
  %rhs2 = call ptr @hidden_inttoptr()
  %cmp1 = icmp eq ptr %m, %lgp
  %cmp2 = icmp eq ptr %m, %rhs2
  call void @witness(i1 %cmp1, i1 %cmp2)
  ret void
}

define void @neg_consistent_fold4() {
; CHECK-LABEL: @neg_consistent_fold4(
; CHECK-NEXT:    call void @witness(i1 false, i1 false)
; CHECK-NEXT:    ret void
;
  %m = alloca i8, i32 4
  %lgp = load ptr, ptr @gp, align 8
  %cmp1 = icmp eq ptr %m, %lgp
  %cmp2 = icmp eq ptr %m, %lgp
  call void @witness(i1 %cmp1, i1 %cmp2)
  ret void
}

; A nocapture call can't cause a consistent result issue as it is (by
; assumption) not able to contain a comparison which might capture the
; address.

declare void @unknown(ptr)

define i1 @consistent_nocapture_inttoptr() {
; CHECK-LABEL: @consistent_nocapture_inttoptr(
; CHECK-NEXT:    [[M1:%.*]] = alloca [4 x i8], align 1
; CHECK-NEXT:    call void @unknown(ptr nocapture nonnull [[M1]])
; CHECK-NEXT:    ret i1 false
;
  %m = alloca i8, i32 4
  call void @unknown(ptr nocapture %m)
  %rhs = inttoptr i64 2048 to ptr
  %cmp = icmp eq ptr %m, %rhs
  ret i1 %cmp
}

define i1 @consistent_nocapture_offset() {
; CHECK-LABEL: @consistent_nocapture_offset(
; CHECK-NEXT:    [[M1:%.*]] = alloca [4 x i8], align 1
; CHECK-NEXT:    call void @unknown(ptr nocapture nonnull [[M1]])
; CHECK-NEXT:    ret i1 false
;
  %m = alloca i8, i32 4
  call void @unknown(ptr nocapture %m)
  %n = alloca i8, i32 4
  %rhs = getelementptr i8, ptr %n, i32 4
  %cmp = icmp eq ptr %m, %rhs
  ret i1 %cmp
}

@gp = global ptr null, align 8

define i1 @consistent_nocapture_through_global() {
; CHECK-LABEL: @consistent_nocapture_through_global(
; CHECK-NEXT:    [[M1:%.*]] = alloca [4 x i8], align 1
; CHECK-NEXT:    call void @unknown(ptr nocapture nonnull [[M1]])
; CHECK-NEXT:    ret i1 false
;
  %m = alloca i8, i32 4
  call void @unknown(ptr nocapture %m)
  %lgp = load ptr, ptr @gp, align 8, !nonnull !{}
  %cmp = icmp eq ptr %m, %lgp
  ret i1 %cmp
}

define void @select_alloca_unrelated_ptr(i1 %c, ptr %p, ptr %p2) {
; CHECK-LABEL: @select_alloca_unrelated_ptr(
; CHECK-NEXT:    [[M:%.*]] = alloca i8, align 1
; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq ptr [[M]], [[P:%.*]]
; CHECK-NEXT:    [[S:%.*]] = select i1 [[C:%.*]], ptr [[M]], ptr [[P2:%.*]]
; CHECK-NEXT:    [[CMP2:%.*]] = icmp eq ptr [[S]], [[P]]
; CHECK-NEXT:    call void @witness(i1 [[CMP1]], i1 [[CMP2]])
; CHECK-NEXT:    ret void
;
  %m = alloca i8
  %cmp1 = icmp eq ptr %m, %p
  %s = select i1 %c, ptr %m, ptr %p2
  %cmp2 = icmp eq ptr %s, %p
  call void @witness(i1 %cmp1, i1 %cmp2)
  ret void
}

define void @alloca_offset_icmp(ptr %p, i32 %offset) {
; CHECK-LABEL: @alloca_offset_icmp(
; CHECK-NEXT:    [[CMP2:%.*]] = icmp eq i32 [[OFFSET:%.*]], 0
; CHECK-NEXT:    call void @witness(i1 false, i1 [[CMP2]])
; CHECK-NEXT:    ret void
;
  %m = alloca [4 x i8]
  %g = getelementptr i8, ptr %m, i32 %offset
  %cmp1 = icmp eq ptr %m, %p
  %cmp2 = icmp eq ptr %m, %g
  call void @witness(i1 %cmp1, i1 %cmp2)
  ret void
}