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llvm-project/llvm/test/Transforms/InstCombine/strlen-1.ll
Florian Hahn 419c6948df [SimplifyLibCalls] Remove over-eager early return in strlen optzns. 
Currently we bail out early for strlen calls with a GEP operand, if none
of the GEP specific optimizations fire. But there could be later
optimizations that still apply,  which we currently miss out on.

An example is that we do not apply the following optimization
   strlen(x) == 0 --> *x == 0

Unless I am missing something, there seems to be no reason for bailing
out early there.

Fixes PR47149.

Reviewed By: lebedev.ri, xbolva00

Differential Revision: https://reviews.llvm.org/D85886
2020-08-27 15:19:45 +01:00

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9.2 KiB
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; 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"
@longer = constant [7 x i8] c"longer\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
@null_hello_mid = constant [13 x i8] c"hello wor\00ld\00"
declare i32 @strlen(i8*)
; Check strlen(string constant) -> integer constant.
define i32 @test_simplify1() {
; CHECK-LABEL: @test_simplify1(
; CHECK-NEXT: ret i32 5
;
%hello_p = getelementptr [6 x i8], [6 x i8]* @hello, i32 0, i32 0
%hello_l = call i32 @strlen(i8* %hello_p)
ret i32 %hello_l
}
define i32 @test_simplify2() {
; CHECK-LABEL: @test_simplify2(
; CHECK-NEXT: ret i32 0
;
%null_p = getelementptr [1 x i8], [1 x i8]* @null, i32 0, i32 0
%null_l = call i32 @strlen(i8* %null_p)
ret i32 %null_l
}
define i32 @test_simplify3() {
; CHECK-LABEL: @test_simplify3(
; CHECK-NEXT: ret i32 0
;
%null_hello_p = getelementptr [7 x i8], [7 x i8]* @null_hello, i32 0, i32 0
%null_hello_l = call i32 @strlen(i8* %null_hello_p)
ret i32 %null_hello_l
}
define i32 @test_simplify4() {
; CHECK-LABEL: @test_simplify4(
; CHECK-NEXT: ret i32 0
;
%len = tail call i32 @strlen(i8* @nullstring) nounwind
ret i32 %len
}
; Check strlen(x) == 0 --> *x == 0.
define i1 @test_simplify5() {
; CHECK-LABEL: @test_simplify5(
; CHECK-NEXT: ret i1 false
;
%hello_p = getelementptr [6 x i8], [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
}
define i1 @test_simplify6(i8* %str_p) {
; CHECK-LABEL: @test_simplify6(
; CHECK-NEXT: [[STRLENFIRST:%.*]] = load i8, i8* [[STR_P:%.*]], align 1
; CHECK-NEXT: [[EQ_NULL:%.*]] = icmp eq i8 [[STRLENFIRST]], 0
; CHECK-NEXT: ret i1 [[EQ_NULL]]
;
%str_l = call i32 @strlen(i8* %str_p)
%eq_null = icmp eq i32 %str_l, 0
ret i1 %eq_null
}
; Check strlen(x) != 0 --> *x != 0.
define i1 @test_simplify7() {
; CHECK-LABEL: @test_simplify7(
; CHECK-NEXT: ret i1 true
;
%hello_p = getelementptr [6 x i8], [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
}
define i1 @test_simplify8(i8* %str_p) {
; CHECK-LABEL: @test_simplify8(
; CHECK-NEXT: [[STRLENFIRST:%.*]] = load i8, i8* [[STR_P:%.*]], align 1
; CHECK-NEXT: [[NE_NULL:%.*]] = icmp ne i8 [[STRLENFIRST]], 0
; CHECK-NEXT: ret i1 [[NE_NULL]]
;
%str_l = call i32 @strlen(i8* %str_p)
%ne_null = icmp ne i32 %str_l, 0
ret i1 %ne_null
}
define i32 @test_simplify9(i1 %x) {
; CHECK-LABEL: @test_simplify9(
; CHECK-NEXT: [[TMP1:%.*]] = select i1 [[X:%.*]], i32 5, i32 6
; CHECK-NEXT: ret i32 [[TMP1]]
;
%hello = getelementptr [6 x i8], [6 x i8]* @hello, i32 0, i32 0
%longer = getelementptr [7 x i8], [7 x i8]* @longer, i32 0, i32 0
%s = select i1 %x, i8* %hello, i8* %longer
%l = call i32 @strlen(i8* %s)
ret i32 %l
}
; Check the case that should be simplified to a sub instruction.
; strlen(@hello + x) --> 5 - x
define i32 @test_simplify10(i32 %x) {
; CHECK-LABEL: @test_simplify10(
; CHECK-NEXT: [[TMP1:%.*]] = sub i32 5, [[X:%.*]]
; CHECK-NEXT: ret i32 [[TMP1]]
;
%hello_p = getelementptr inbounds [6 x i8], [6 x i8]* @hello, i32 0, i32 %x
%hello_l = call i32 @strlen(i8* %hello_p)
ret i32 %hello_l
}
; strlen(@null_hello_mid + (x & 7)) --> 9 - (x & 7)
define i32 @test_simplify11(i32 %x) {
; CHECK-LABEL: @test_simplify11(
; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], 7
; CHECK-NEXT: [[TMP1:%.*]] = sub nuw nsw i32 9, [[AND]]
; CHECK-NEXT: ret i32 [[TMP1]]
;
%and = and i32 %x, 7
%hello_p = getelementptr inbounds [13 x i8], [13 x i8]* @null_hello_mid, i32 0, i32 %and
%hello_l = call i32 @strlen(i8* %hello_p)
ret i32 %hello_l
}
; Check cases that shouldn't be simplified.
define i32 @test_no_simplify1() {
; CHECK-LABEL: @test_no_simplify1(
; CHECK-NEXT: [[A_L:%.*]] = call i32 @strlen(i8* nonnull dereferenceable(1) getelementptr inbounds ([32 x i8], [32 x i8]* @a, i32 0, i32 0))
; CHECK-NEXT: ret i32 [[A_L]]
;
%a_p = getelementptr [32 x i8], [32 x i8]* @a, i32 0, i32 0
%a_l = call i32 @strlen(i8* %a_p)
ret i32 %a_l
}
; strlen(@null_hello + x) should not be simplified to a sub instruction.
define i32 @test_no_simplify2(i32 %x) {
; CHECK-LABEL: @test_no_simplify2(
; CHECK-NEXT: [[HELLO_P:%.*]] = getelementptr inbounds [7 x i8], [7 x i8]* @null_hello, i32 0, i32 [[X:%.*]]
; CHECK-NEXT: [[HELLO_L:%.*]] = call i32 @strlen(i8* nonnull [[HELLO_P]])
; CHECK-NEXT: ret i32 [[HELLO_L]]
;
%hello_p = getelementptr inbounds [7 x i8], [7 x i8]* @null_hello, i32 0, i32 %x
%hello_l = call i32 @strlen(i8* %hello_p)
ret i32 %hello_l
}
define i32 @test_no_simplify2_no_null_opt(i32 %x) #0 {
; CHECK-LABEL: @test_no_simplify2_no_null_opt(
; CHECK-NEXT: [[HELLO_P:%.*]] = getelementptr inbounds [7 x i8], [7 x i8]* @null_hello, i32 0, i32 [[X:%.*]]
; CHECK-NEXT: [[HELLO_L:%.*]] = call i32 @strlen(i8* [[HELLO_P]])
; CHECK-NEXT: ret i32 [[HELLO_L]]
;
%hello_p = getelementptr inbounds [7 x i8], [7 x i8]* @null_hello, i32 0, i32 %x
%hello_l = call i32 @strlen(i8* %hello_p)
ret i32 %hello_l
}
; strlen(@null_hello_mid + (x & 15)) should not be simplified to a sub instruction.
define i32 @test_no_simplify3(i32 %x) {
; CHECK-LABEL: @test_no_simplify3(
; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], 15
; CHECK-NEXT: [[HELLO_P:%.*]] = getelementptr inbounds [13 x i8], [13 x i8]* @null_hello_mid, i32 0, i32 [[AND]]
; CHECK-NEXT: [[HELLO_L:%.*]] = call i32 @strlen(i8* nonnull [[HELLO_P]])
; CHECK-NEXT: ret i32 [[HELLO_L]]
;
%and = and i32 %x, 15
%hello_p = getelementptr inbounds [13 x i8], [13 x i8]* @null_hello_mid, i32 0, i32 %and
%hello_l = call i32 @strlen(i8* %hello_p)
ret i32 %hello_l
}
define i32 @test_no_simplify3_on_null_opt(i32 %x) #0 {
; CHECK-LABEL: @test_no_simplify3_on_null_opt(
; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], 15
; CHECK-NEXT: [[HELLO_P:%.*]] = getelementptr inbounds [13 x i8], [13 x i8]* @null_hello_mid, i32 0, i32 [[AND]]
; CHECK-NEXT: [[HELLO_L:%.*]] = call i32 @strlen(i8* [[HELLO_P]])
; CHECK-NEXT: ret i32 [[HELLO_L]]
;
%and = and i32 %x, 15
%hello_p = getelementptr inbounds [13 x i8], [13 x i8]* @null_hello_mid, i32 0, i32 %and
%hello_l = call i32 @strlen(i8* %hello_p)
ret i32 %hello_l
}
define i32 @test1(i8* %str) {
; CHECK-LABEL: @test1(
; CHECK-NEXT: [[LEN:%.*]] = tail call i32 @strlen(i8* nonnull dereferenceable(1) [[STR:%.*]]) #1
; CHECK-NEXT: ret i32 [[LEN]]
;
%len = tail call i32 @strlen(i8* %str) nounwind
ret i32 %len
}
define i32 @test2(i8* %str) #0 {
; CHECK-LABEL: @test2(
; CHECK-NEXT: [[LEN:%.*]] = tail call i32 @strlen(i8* [[STR:%.*]]) #1
; CHECK-NEXT: ret i32 [[LEN]]
;
%len = tail call i32 @strlen(i8* %str) nounwind
ret i32 %len
}
; Test cases for PR47149.
define i1 @strlen0_after_write_to_first_byte_global() {
; CHECK-LABEL: @strlen0_after_write_to_first_byte_global(
; CHECK-NEXT: store i8 49, i8* getelementptr inbounds ([32 x i8], [32 x i8]* @a, i32 0, i32 0), align 16
; CHECK-NEXT: ret i1 false
;
store i8 49, i8* getelementptr inbounds ([32 x i8], [32 x i8]* @a, i64 0, i64 0), align 16
%len = tail call i32 @strlen(i8* nonnull dereferenceable(1) getelementptr inbounds ([32 x i8], [32 x i8]* @a, i64 0, i64 0))
%cmp = icmp eq i32 %len, 0
ret i1 %cmp
}
define i1 @strlen0_after_write_to_second_byte_global() {
; CHECK-LABEL: @strlen0_after_write_to_second_byte_global(
; CHECK-NEXT: store i8 49, i8* getelementptr inbounds ([32 x i8], [32 x i8]* @a, i32 0, i32 1), align 16
; CHECK-NEXT: [[STRLENFIRST:%.*]] = load i8, i8* getelementptr inbounds ([32 x i8], [32 x i8]* @a, i32 0, i32 0), align 1
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[STRLENFIRST]], 0
; CHECK-NEXT: ret i1 [[CMP]]
;
store i8 49, i8* getelementptr inbounds ([32 x i8], [32 x i8]* @a, i64 0, i64 1), align 16
%len = tail call i32 @strlen(i8* nonnull dereferenceable(1) getelementptr inbounds ([32 x i8], [32 x i8]* @a, i64 0, i64 0))
%cmp = icmp eq i32 %len, 0
ret i1 %cmp
}
define i1 @strlen0_after_write_to_first_byte(i8 *%ptr) {
; CHECK-LABEL: @strlen0_after_write_to_first_byte(
; CHECK-NEXT: store i8 49, i8* [[PTR:%.*]], align 1
; CHECK-NEXT: ret i1 false
;
store i8 49, i8* %ptr
%len = tail call i32 @strlen(i8* nonnull dereferenceable(1) %ptr)
%cmp = icmp eq i32 %len, 0
ret i1 %cmp
}
define i1 @strlen0_after_write_to_second_byte(i8 *%ptr) {
; CHECK-LABEL: @strlen0_after_write_to_second_byte(
; CHECK-NEXT: [[GEP:%.*]] = getelementptr i8, i8* [[PTR:%.*]], i32 1
; CHECK-NEXT: store i8 49, i8* [[GEP]], align 1
; CHECK-NEXT: [[STRLENFIRST:%.*]] = load i8, i8* [[PTR]], align 1
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[STRLENFIRST]], 0
; CHECK-NEXT: ret i1 [[CMP]]
;
%gep = getelementptr i8, i8* %ptr, i64 1
store i8 49, i8* %gep
%len = tail call i32 @strlen(i8* nonnull dereferenceable(1) %ptr)
%cmp = icmp eq i32 %len, 0
ret i1 %cmp
}
attributes #0 = { null_pointer_is_valid }
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