test/Transforms/InstCombine/strlen-1.ll

; Test that the strlen library call simplifier works correctly.
;
; RUN: opt < %s -instcombine -S | FileCheck %s

target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"

@hello = constant [6 x i8] c"hello\00"
@null = constant [1 x i8] zeroinitializer
@null_hello = constant [7 x i8] c"\00hello\00"
@nullstring = constant i8 0
@a = common global [32 x i8] zeroinitializer, align 1

declare i32 @strlen(i8*)

; Check strlen(string constant) -> integer constant.

define i32 @test_simplify1() {
; CHECK: @test_simplify1
  %hello_p = getelementptr [6 x i8]* @hello, i32 0, i32 0
  %hello_l = call i32 @strlen(i8* %hello_p)
  ret i32 %hello_l
; CHECK-NEXT: ret i32 5
}

define i32 @test_simplify2() {
; CHECK: @test_simplify2
  %null_p = getelementptr [1 x i8]* @null, i32 0, i32 0
  %null_l = call i32 @strlen(i8* %null_p)
  ret i32 %null_l
; CHECK-NEXT: ret i32 0
}

define i32 @test_simplify3() {
; CHECK: @test_simplify3
  %null_hello_p = getelementptr [7 x i8]* @null_hello, i32 0, i32 0
  %null_hello_l = call i32 @strlen(i8* %null_hello_p)
  ret i32 %null_hello_l
; CHECK-NEXT: ret i32 0
}

define i32 @test_simplify4() {
; CHECK: @test_simplify4
  %len = tail call i32 @strlen(i8* @nullstring) nounwind
  ret i32 %len
; CHECK-NEXT: ret i32 0
}

; Check strlen(x) == 0 --> *x == 0.

define i1 @test_simplify5() {
; CHECK: @test_simplify5
  %hello_p = getelementptr [6 x i8]* @hello, i32 0, i32 0
  %hello_l = call i32 @strlen(i8* %hello_p)
  %eq_hello = icmp eq i32 %hello_l, 0
  ret i1 %eq_hello
; CHECK-NEXT: ret i1 false
}

define i1 @test_simplify6() {
; CHECK: @test_simplify6
  %null_p = getelementptr [1 x i8]* @null, i32 0, i32 0
  %null_l = call i32 @strlen(i8* %null_p)
  %eq_null = icmp eq i32 %null_l, 0
  ret i1 %eq_null
; CHECK-NEXT: ret i1 true
}

; Check strlen(x) != 0 --> *x != 0.

define i1 @test_simplify7() {
; CHECK: @test_simplify7
  %hello_p = getelementptr [6 x i8]* @hello, i32 0, i32 0
  %hello_l = call i32 @strlen(i8* %hello_p)
  %ne_hello = icmp ne i32 %hello_l, 0
  ret i1 %ne_hello
; CHECK-NEXT: ret i1 true
}

define i1 @test_simplify8() {
; CHECK: @test_simplify8
  %null_p = getelementptr [1 x i8]* @null, i32 0, i32 0
  %null_l = call i32 @strlen(i8* %null_p)
  %ne_null = icmp ne i32 %null_l, 0
  ret i1 %ne_null
; CHECK-NEXT: ret i1 false
}

; Check cases that shouldn't be simplified.

define i32 @test_no_simplify1() {
; CHECK: @test_no_simplify1
  %a_p = getelementptr [32 x i8]* @a, i32 0, i32 0
  %a_l = call i32 @strlen(i8* %a_p)
; CHECK-NEXT: %a_l = call i32 @strlen
  ret i32 %a_l
; CHECK-NEXT: ret i32 %a_l
}