llvm/test/Transforms/InstCombine/strncmp-4.ll

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; Verify that strncmp calls with members of constant structs are folded.
;
; RUN: opt < %s -passes=instcombine -S | FileCheck %s

; struct A { char a[3], b[4], c[4]; };
%struct.A = type { [3 x i8], [4 x i8], [4 x i8] }

@a = constant %struct.A { [3 x i8] c"123", [4 x i8] c"1231", [4 x i8] c"2345" }

declare i32 @strncmp(ptr, ptr, i64)

define void @fold_strncmp_Aa_b(ptr %pcmp) {
; CHECK-LABEL: @fold_strncmp_Aa_b(
; CHECK-NEXT:    store i32 0, ptr [[PCMP:%.*]], align 4
; CHECK-NEXT:    [[PCMP1:%.*]] = getelementptr i32, ptr [[PCMP]], i64 1
; CHECK-NEXT:    store i32 0, ptr [[PCMP1]], align 4
; CHECK-NEXT:    [[PCMP2:%.*]] = getelementptr i32, ptr [[PCMP]], i64 2
; CHECK-NEXT:    store i32 0, ptr [[PCMP2]], align 4
; CHECK-NEXT:    [[PCMP3:%.*]] = getelementptr i32, ptr [[PCMP]], i64 3
; CHECK-NEXT:    store i32 0, ptr [[PCMP3]], align 4
; CHECK-NEXT:    [[PCMP4:%.*]] = getelementptr i32, ptr [[PCMP]], i64 4
; CHECK-NEXT:    store i32 0, ptr [[PCMP4]], align 4
; CHECK-NEXT:    [[PCMP5:%.*]] = getelementptr i32, ptr [[PCMP]], i64 5
; CHECK-NEXT:    store i32 0, ptr [[PCMP5]], align 4
; CHECK-NEXT:    [[PCMP6:%.*]] = getelementptr i32, ptr [[PCMP]], i64 6
; CHECK-NEXT:    store i32 0, ptr [[PCMP6]], align 4
; CHECK-NEXT:    [[PCMP7:%.*]] = getelementptr i32, ptr [[PCMP]], i64 7
; CHECK-NEXT:    store i32 -1, ptr [[PCMP7]], align 4
; CHECK-NEXT:    [[PCMP8:%.*]] = getelementptr i32, ptr [[PCMP]], i64 8
; CHECK-NEXT:    store i32 -1, ptr [[PCMP8]], align 4
; CHECK-NEXT:    [[PCMP9:%.*]] = getelementptr i32, ptr [[PCMP]], i64 9
; CHECK-NEXT:    store i32 -1, ptr [[PCMP9]], align 4
; CHECK-NEXT:    ret void
;
; p1 = a.a
; p2 = a.b
  %p2 = getelementptr %struct.A, ptr @a, i32 0, i32 1, i32 0

; Fold strncmp(a.a = "123", a.b = "1231", 0) to 0.
  %cmp0 = call i32 @strncmp(ptr @a, ptr %p2, i64 0)
  store i32 %cmp0, ptr %pcmp

; Fold strncmp(a.a = "123", a.b = "1231", 1) to 0.
  %cmp1 = call i32 @strncmp(ptr @a, ptr %p2, i64 1)
  %pcmp1 = getelementptr i32, ptr %pcmp, i64 1
  store i32 %cmp1, ptr %pcmp1

; Fold strncmp(a.a = "123", a.b = "1231", 2) to 0.
  %cmp2 = call i32 @strncmp(ptr @a, ptr %p2, i64 2)
  %pcmp2 = getelementptr i32, ptr %pcmp, i64 2
  store i32 %cmp2, ptr %pcmp2

; Fold strncmp(a.a = "123", a.b = "1231", 3) to 0.
  %cmp3 = call i32 @strncmp(ptr @a, ptr %p2, i64 3)
  %pcmp3 = getelementptr i32, ptr %pcmp, i64 3
  store i32 %cmp3, ptr %pcmp3

; Fold strncmp(a.a = "123", a.b = "1231", 4) to 0.
; In this and the subsequent tests, reading past the end of a.a is
; strictly undefined in C/C++ (because it forms a pointer to a distinct
; subobject) but handling such cases as if they were well-defined is
; simpler than trying to exclude them.

  %cmp4 = call i32 @strncmp(ptr @a, ptr %p2, i64 4)
  %pcmp4 = getelementptr i32, ptr %pcmp, i64 4
  store i32 %cmp4, ptr %pcmp4

; Fold strncmp("123", "1231" "2", 5) to 0.
  %cmp5 = call i32 @strncmp(ptr @a, ptr %p2, i64 5)
  %pcmp5 = getelementptr i32, ptr %pcmp, i64 5
  store i32 %cmp5, ptr %pcmp5

; Fold strncmp("123", "1231" "23", 6) to 0.
  %cmp6 = call i32 @strncmp(ptr @a, ptr %p2, i64 6)
  %pcmp6 = getelementptr i32, ptr %pcmp, i64 6
  store i32 %cmp6, ptr %pcmp6

; Fold strncmp("123", "1231" "2345", 7) to 1.
  %cmp7 = call i32 @strncmp(ptr @a, ptr %p2, i64 7)
  %pcmp7 = getelementptr i32, ptr %pcmp, i64 7
  store i32 %cmp7, ptr %pcmp7

; Fold strncmp("123", "1231" "2345", 8) to 1.
  %cmp8 = call i32 @strncmp(ptr @a, ptr %p2, i64 8)
  %pcmp8 = getelementptr i32, ptr %pcmp, i64 8
  store i32 %cmp8, ptr %pcmp8

; Fold strncmp("123", "1231" "2345", 9) to 1.
  %cmp9 = call i32 @strncmp(ptr @a, ptr %p2, i64 9)
  %pcmp9 = getelementptr i32, ptr %pcmp, i64 9
  store i32 %cmp9, ptr %pcmp9

  ret void
}


define void @fold_strncmp_Ab_a(ptr %pcmp) {
; CHECK-LABEL: @fold_strncmp_Ab_a(
; CHECK-NEXT:    store i32 0, ptr [[PCMP:%.*]], align 4
; CHECK-NEXT:    [[PCMP1:%.*]] = getelementptr i32, ptr [[PCMP]], i64 1
; CHECK-NEXT:    store i32 0, ptr [[PCMP1]], align 4
; CHECK-NEXT:    [[PCMP2:%.*]] = getelementptr i32, ptr [[PCMP]], i64 2
; CHECK-NEXT:    store i32 0, ptr [[PCMP2]], align 4
; CHECK-NEXT:    [[PCMP3:%.*]] = getelementptr i32, ptr [[PCMP]], i64 3
; CHECK-NEXT:    store i32 0, ptr [[PCMP3]], align 4
; CHECK-NEXT:    [[PCMP4:%.*]] = getelementptr i32, ptr [[PCMP]], i64 4
; CHECK-NEXT:    store i32 1, ptr [[PCMP4]], align 4
; CHECK-NEXT:    [[PCMP5:%.*]] = getelementptr i32, ptr [[PCMP]], i64 5
; CHECK-NEXT:    store i32 1, ptr [[PCMP5]], align 4
; CHECK-NEXT:    ret void
;
; p1 = &a.b[3]
  %p1 = getelementptr %struct.A, ptr @a, i32 0, i32 1, i32 3
; p2 = &a.a

; Fold strncmp(a.a = "123", &a.b[3] = "1" "2345", 0) to 0.
  %cmp0 = call i32 @strncmp(ptr %p1, ptr @a, i64 0)
  store i32 %cmp0, ptr %pcmp

; Fold strncmp(a.a = "123", &a.b[3] = "1" "2345", 1) to 0.
  %cmp1 = call i32 @strncmp(ptr %p1, ptr @a, i64 1)
  %pcmp1 = getelementptr i32, ptr %pcmp, i64 1
  store i32 %cmp1, ptr %pcmp1

; Fold strncmp(a.a = "123", &a.b[3] = "1" "2345", 2) to 0.
  %cmp2 = call i32 @strncmp(ptr %p1, ptr @a, i64 2)
  %pcmp2 = getelementptr i32, ptr %pcmp, i64 2
  store i32 %cmp2, ptr %pcmp2

; Fold strncmp(a.a = "123", &a.b[3] = "1" "2345", 3) to 0.
  %cmp3 = call i32 @strncmp(ptr %p1, ptr @a, i64 3)
  %pcmp3 = getelementptr i32, ptr %pcmp, i64 3
  store i32 %cmp3, ptr %pcmp3

; Fold strncmp(a.a = "123", &a.b[3] = "1" "2345", 4) to 1.
  %cmp4 = call i32 @strncmp(ptr %p1, ptr @a, i64 4)
  %pcmp4 = getelementptr i32, ptr %pcmp, i64 4
  store i32 %cmp4, ptr %pcmp4

; Fold strncmp(a.a = "123", &a.b[3] = "1" "2345", 5) to 1.
  %cmp5 = call i32 @strncmp(ptr %p1, ptr @a, i64 5)
  %pcmp5 = getelementptr i32, ptr %pcmp, i64 5
  store i32 %cmp5, ptr %pcmp5

  ret void
}