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llvm-project/clang/test/CodeGen/vla.c
Richard Smith 552c6c2328 PR44406: Follow behavior of array bound constant folding in more recent versions of GCC. 
Old GCC used to aggressively fold VLAs to constant-bound arrays at block
scope in GNU mode. That's non-conforming, and more modern versions of
GCC only do this at file scope. Update Clang to do the same.

Also promote the warning for this from off-by-default to on-by-default
in all cases; more recent versions of GCC likewise warn on this by
default.

This is still slightly more permissive than GCC, as pointed out in
PR44406, as we still fold VLAs to constant arrays in structs, but that
seems justifiable given that we don't support VLA-in-struct (and don't
intend to ever support it), but GCC does.

Differential Revision: https://reviews.llvm.org/D89523
2020-10-16 14:34:35 -07:00

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// RUN: %clang_cc1 -triple i386-unknown-unknown %s -emit-llvm -o - | FileCheck %s -check-prefixes=CHECK,NULL-INVALID
// RUN: %clang_cc1 -triple i386-unknown-unknown %s -emit-llvm -fno-delete-null-pointer-checks -o - | FileCheck %s -check-prefixes=CHECK,NULL-VALID
int b(char* x);
// Extremely basic VLA test
void a(int x) {
char arry[x];
arry[0] = 10;
b(arry);
}
int c(int n)
{
return sizeof(int[n]);
}
int f0(int x) {
int vla[x];
return vla[x-1];
}
void
f(int count)
{
int a[count];
do { } while (0);
if (a[0] != 3) {
}
}
void g(int count) {
// Make sure we emit sizes correctly in some obscure cases
int (*a[5])[count];
int (*b)[][count];
}
// rdar://8403108
// CHECK-LABEL: define void @f_8403108
void f_8403108(unsigned x) {
// CHECK: call i8* @llvm.stacksave()
char s1[x];
while (1) {
// CHECK: call i8* @llvm.stacksave()
char s2[x];
if (1)
break;
// CHECK: call void @llvm.stackrestore(i8*
}
// CHECK: call void @llvm.stackrestore(i8*
}
// pr7827
void function(short width, int data[][width]) {} // expected-note {{passing argument to parameter 'data' here}}
void test() {
int bork[4][13];
// CHECK: call void @function(i16 signext 1, i32* null)
function(1, 0);
// CHECK: call void @function(i16 signext 1, i32* inttoptr
function(1, 0xbadbeef); // expected-warning {{incompatible integer to pointer conversion passing}}
// CHECK: call void @function(i16 signext 1, i32* {{.*}})
function(1, bork);
}
void function1(short width, int data[][width][width]) {}
void test1() {
int bork[4][13][15];
// CHECK: call void @function1(i16 signext 1, i32* {{.*}})
function1(1, bork);
// CHECK: call void @function(i16 signext 1, i32* {{.*}})
function(1, bork[2]);
}
// rdar://8476159
static int GLOB;
int test2(int n)
{
GLOB = 0;
char b[1][n+3]; /* Variable length array. */
// CHECK: [[tmp_1:%.*]] = load i32, i32* @GLOB, align 4
// CHECK-NEXT: add nsw i32 [[tmp_1]], 1
__typeof__(b[GLOB++]) c;
return GLOB;
}
// http://llvm.org/PR8567
// CHECK-LABEL: define double @test_PR8567
double test_PR8567(int n, double (*p)[n][5]) {
// CHECK: [[NV:%.*]] = alloca i32, align 4
// CHECK-NEXT: [[PV:%.*]] = alloca [5 x double]*, align 4
// CHECK-NEXT: store
// CHECK-NEXT: store
// CHECK-NEXT: [[N:%.*]] = load i32, i32* [[NV]], align 4
// CHECK-NEXT: [[P:%.*]] = load [5 x double]*, [5 x double]** [[PV]], align 4
// CHECK-NEXT: [[T0:%.*]] = mul nsw i32 1, [[N]]
// CHECK-NEXT: [[T1:%.*]] = getelementptr inbounds [5 x double], [5 x double]* [[P]], i32 [[T0]]
// CHECK-NEXT: [[T2:%.*]] = getelementptr inbounds [5 x double], [5 x double]* [[T1]], i32 2
// CHECK-NEXT: [[T3:%.*]] = getelementptr inbounds [5 x double], [5 x double]* [[T2]], i32 0, i32 3
// CHECK-NEXT: [[T4:%.*]] = load double, double* [[T3]]
// CHECK-NEXT: ret double [[T4]]
return p[1][2][3];
}
int test4(unsigned n, char (*p)[n][n+1][6]) {
// CHECK-LABEL: define i32 @test4(
// CHECK: [[N:%.*]] = alloca i32, align 4
// CHECK-NEXT: [[P:%.*]] = alloca [6 x i8]*, align 4
// CHECK-NEXT: [[P2:%.*]] = alloca [6 x i8]*, align 4
// CHECK-NEXT: store i32
// CHECK-NEXT: store [6 x i8]*
// VLA captures.
// CHECK-NEXT: [[DIM0:%.*]] = load i32, i32* [[N]], align 4
// CHECK-NEXT: [[T0:%.*]] = load i32, i32* [[N]], align 4
// CHECK-NEXT: [[DIM1:%.*]] = add i32 [[T0]], 1
// CHECK-NEXT: [[T0:%.*]] = load [6 x i8]*, [6 x i8]** [[P]], align 4
// CHECK-NEXT: [[T1:%.*]] = load i32, i32* [[N]], align 4
// CHECK-NEXT: [[T2:%.*]] = udiv i32 [[T1]], 2
// CHECK-NEXT: [[T3:%.*]] = mul nuw i32 [[DIM0]], [[DIM1]]
// CHECK-NEXT: [[T4:%.*]] = mul nsw i32 [[T2]], [[T3]]
// CHECK-NEXT: [[T5:%.*]] = getelementptr inbounds [6 x i8], [6 x i8]* [[T0]], i32 [[T4]]
// CHECK-NEXT: [[T6:%.*]] = load i32, i32* [[N]], align 4
// CHECK-NEXT: [[T7:%.*]] = udiv i32 [[T6]], 4
// CHECK-NEXT: [[T8:%.*]] = sub i32 0, [[T7]]
// CHECK-NEXT: [[T9:%.*]] = mul nuw i32 [[DIM0]], [[DIM1]]
// CHECK-NEXT: [[T10:%.*]] = mul nsw i32 [[T8]], [[T9]]
// CHECK-NEXT: [[T11:%.*]] = getelementptr inbounds [6 x i8], [6 x i8]* [[T5]], i32 [[T10]]
// CHECK-NEXT: store [6 x i8]* [[T11]], [6 x i8]** [[P2]], align 4
__typeof(p) p2 = (p + n/2) - n/4;
// CHECK-NEXT: [[T0:%.*]] = load [6 x i8]*, [6 x i8]** [[P2]], align 4
// CHECK-NEXT: [[T1:%.*]] = load [6 x i8]*, [6 x i8]** [[P]], align 4
// CHECK-NEXT: [[T2:%.*]] = ptrtoint [6 x i8]* [[T0]] to i32
// CHECK-NEXT: [[T3:%.*]] = ptrtoint [6 x i8]* [[T1]] to i32
// CHECK-NEXT: [[T4:%.*]] = sub i32 [[T2]], [[T3]]
// CHECK-NEXT: [[T5:%.*]] = mul nuw i32 [[DIM0]], [[DIM1]]
// CHECK-NEXT: [[T6:%.*]] = mul nuw i32 6, [[T5]]
// CHECK-NEXT: [[T7:%.*]] = sdiv exact i32 [[T4]], [[T6]]
// CHECK-NEXT: ret i32 [[T7]]
return p2 - p;
}
// rdar://11485774
void test5(void)
{
// CHECK-LABEL: define void @test5(
int a[5], i = 0;
// CHECK: [[A:%.*]] = alloca [5 x i32], align 4
// CHECK-NEXT: [[I:%.*]] = alloca i32, align 4
// CHECK-NEXT: [[CL:%.*]] = alloca i32*, align 4
// CHECK-NEXT: store i32 0, i32* [[I]], align 4
(typeof(++i, (int (*)[i])a)){&a} += 0;
// CHECK-NEXT: [[Z:%.*]] = load i32, i32* [[I]], align 4
// CHECK-NEXT: [[INC:%.*]] = add nsw i32 [[Z]], 1
// CHECK-NEXT: store i32 [[INC]], i32* [[I]], align 4
// CHECK-NEXT: [[O:%.*]] = load i32, i32* [[I]], align 4
// CHECK-NEXT: [[AR:%.*]] = getelementptr inbounds [5 x i32], [5 x i32]* [[A]], i32 0, i32 0
// CHECK-NEXT: [[T:%.*]] = bitcast [5 x i32]* [[A]] to i32*
// CHECK-NEXT: store i32* [[T]], i32** [[CL]]
// CHECK-NEXT: [[TH:%.*]] = load i32*, i32** [[CL]]
// CHECK-NEXT: [[VLAIX:%.*]] = mul nsw i32 0, [[O]]
// CHECK-NEXT: [[ADDPTR:%.*]] = getelementptr inbounds i32, i32* [[TH]], i32 [[VLAIX]]
// CHECK-NEXT: store i32* [[ADDPTR]], i32** [[CL]]
}
void test6(void)
{
// CHECK-LABEL: define void @test6(
int n = 20, **a, i=0;
// CHECK: [[N:%.*]] = alloca i32, align 4
// CHECK-NEXT: [[A:%.*]] = alloca i32**, align 4
// CHECK-NEXT: [[I:%.*]] = alloca i32, align 4
(int (**)[i]){&a}[0][1][5] = 0;
// CHECK-NEXT: [[CL:%.*]] = alloca i32**, align 4
// CHECK-NEXT: store i32 20, i32* [[N]], align 4
// CHECK-NEXT: store i32 0, i32* [[I]], align 4
// CHECK-NEXT: [[Z:%.*]] = load i32, i32* [[I]], align 4
// CHECK-NEXT: [[O:%.*]] = bitcast i32*** [[A]] to i32**
// CHECK-NEXT: store i32** [[O]], i32*** [[CL]]
// CHECK-NEXT: [[T:%.*]] = load i32**, i32*** [[CL]]
// CHECK-NEXT: [[IX:%.*]] = getelementptr inbounds i32*, i32** [[T]], i32 0
// CHECK-NEXT: [[TH:%.*]] = load i32*, i32** [[IX]], align 4
// CHECK-NEXT: [[F:%.*]] = mul nsw i32 1, [[Z]]
// CHECK-NEXT: [[IX1:%.*]] = getelementptr inbounds i32, i32* [[TH]], i32 [[F]]
// CHECK-NEXT: [[IX2:%.*]] = getelementptr inbounds i32, i32* [[IX1]], i32 5
// CHECK-NEXT: store i32 0, i32* [[IX2]], align 4
}
// Follow gcc's behavior for VLAs in parameter lists. PR9559.
void test7(int a[b(0)]) {
// CHECK-LABEL: define void @test7(
// CHECK: call i32 @b(i8* null)
}
// Make sure we emit dereferenceable or nonnull when the static keyword is
// provided.
void test8(int a[static 3]) { }
// CHECK: define void @test8(i32* align 4 dereferenceable(12) %a)
void test9(int n, int a[static n]) { }
// NULL-INVALID: define void @test9(i32 %n, i32* nonnull align 4 %a)
// NULL-VALID: define void @test9(i32 %n, i32* align 4 %a)
// Make sure a zero-sized static array extent is still required to be nonnull.
void test10(int a[static 0]) {}
// NULL-INVALID: define void @test10(i32* nonnull align 4 %a)
// NULL-VALID: define void @test10(i32* align 4 %a)
const int constant = 32;
// CHECK: define {{.*}}pr44406(
int pr44406() {
int n = 0;
// Do not fold this VLA to an array of constant bound; that would miscompile
// this testcase.
char c[1][(constant - constant) + 3];
// CHECK: store i32 1,
sizeof(c[n = 1]);
return n;
}
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