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llvm-project/clang/test/CodeGen/vla.c
Aaron Ballman 7068aa9841 Strengthen -Wint-conversion to default to an error 
Clang has traditionally allowed C programs to implicitly convert
integers to pointers and pointers to integers, despite it not being
valid to do so except under special circumstances (like converting the
integer 0, which is the null pointer constant, to a pointer). In C89,
this would result in undefined behavior per 3.3.4, and in C99 this rule
was strengthened to be a constraint violation instead. Constraint
violations are most often handled as an error.

This patch changes the warning to default to an error in all C modes
(it is already an error in C++). This gives us better security posture
by calling out potential programmer mistakes in code but still allows
users who need this behavior to use -Wno-error=int-conversion to retain
the warning behavior, or -Wno-int-conversion to silence the diagnostic
entirely.

Differential Revision: https://reviews.llvm.org/D129881
2022-07-22 15:24:54 -04:00

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// RUN: %clang_cc1 -no-opaque-pointers -Wno-int-conversion -triple i386-unknown-unknown %s -emit-llvm -o - | FileCheck %s -check-prefixes=CHECK,NULL-INVALID
// RUN: %clang_cc1 -no-opaque-pointers -Wno-int-conversion -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(void) {
int bork[4][13];
// CHECK: call void @function(i16 noundef signext 1, i32* noundef null)
function(1, 0);
// CHECK: call void @function(i16 noundef signext 1, i32* noundef inttoptr
function(1, 0xbadbeef); // expected-warning {{incompatible integer to pointer conversion passing}}
// CHECK: call void @function(i16 noundef signext 1, i32* noundef {{.*}})
function(1, bork);
}
void function1(short width, int data[][width][width]) {}
void test1(void) {
int bork[4][13][15];
// CHECK: call void @function1(i16 noundef signext 1, i32* noundef {{.*}})
function1(1, bork);
// CHECK: call void @function(i16 noundef signext 1, i32* noundef {{.*}})
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* noundef 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* noundef align 4 dereferenceable(12) %a)
void test9(int n, int a[static n]) { }
// NULL-INVALID: define{{.*}} void @test9(i32 noundef %n, i32* noundef nonnull align 4 %a)
// NULL-VALID: define{{.*}} void @test9(i32 noundef %n, i32* noundef 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* noundef nonnull align 4 %a)
// NULL-VALID: define{{.*}} void @test10(i32* noundef align 4 %a)
const int constant = 32;
// CHECK: define {{.*}}pr44406(
int pr44406(void) {
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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