+; Test that the strspn 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"
+
+@abcba = constant [6 x i8] c"abcba\00"
+@abc = constant [4 x i8] c"abc\00"
+@null = constant [1 x i8] zeroinitializer
+
+declare i64 @strspn(i8*, i8*)
+
+; Check strspn(s, "") -> 0.
+
+define i64 @test_simplify1(i8* %str) {
+; CHECK: @test_simplify1
+ %pat = getelementptr [1 x i8]* @null, i32 0, i32 0
+
+ %ret = call i64 @strspn(i8* %str, i8* %pat)
+ ret i64 %ret
+; CHECK-NEXT: ret i64 0
+}
+
+; Check strspn("", s) -> 0.
+
+define i64 @test_simplify2(i8* %pat) {
+; CHECK: @test_simplify2
+ %str = getelementptr [1 x i8]* @null, i32 0, i32 0
+
+ %ret = call i64 @strspn(i8* %str, i8* %pat)
+ ret i64 %ret
+; CHECK-NEXT: ret i64 0
+}
+
+; Check strspn(s1, s2), where s1 and s2 are constants.
+
+define i64 @test_simplify3() {
+; CHECK: @test_simplify3
+ %str = getelementptr [6 x i8]* @abcba, i32 0, i32 0
+ %pat = getelementptr [4 x i8]* @abc, i32 0, i32 0
+
+ %ret = call i64 @strspn(i8* %str, i8* %pat)
+ ret i64 %ret
+; CHECK-NEXT: ret i64 5
+}
+
+; Check cases that shouldn't be simplified.
+
+define i64 @test_no_simplify1(i8* %str, i8* %pat) {
+; CHECK: @test_no_simplify1
+
+ %ret = call i64 @strspn(i8* %str, i8* %pat)
+; CHECK-NEXT: %ret = call i64 @strspn(i8* %str, i8* %pat)
+ ret i64 %ret
+; CHECK-NEXT: ret i64 %ret
+}