llvm-capstone/clang/test/Parser/ms-inline-asm.c
Tom Honermann 0982db188b [Clang] reject bit-fields as instruction operands in Microsoft style inline asm blocks.
MSVC allows bit-fields to be specified as instruction operands in inline asm
blocks. Such references are resolved to the address of the allocation unit that
the named bitfield is a part of. The result is that reads and writes of such
operands will read or mutate nearby bit-fields stored in the same allocation
unit. This is a surprising behavior for which MSVC issues warning C4401,
"'<identifier>': member is bit field". Intel's icc compiler also allows such
bit-field references, but does not issue a diagnostic.

Prior to this change, Clang fails the following assertion when a bit-field is
referenced in such instructions:
  clang/lib/CodeGen/CGValue.h:338: llvm::Value* clang::CodeGen::LValue::getPointer(clang::CodeGen::CodeGenFunction&) const: Assertion `isSimple()' failed.
In non-assert enabled builds, Clang's behavior appears to match the behavior
of the MSVC and icc compilers, though it is unknown if that is by design or
happenstance.

Following this change, attempts to use a bit-field as an instruction operand
in Microsoft style asm blocks is diagnosed as an error due to the risk of
unintentionally reading or writing nearby bit-fields.

Fixes https://github.com/llvm/llvm-project/issues/57791

Reviewed By: erichkeane, aaron.ballman

Differential Revision: https://reviews.llvm.org/D135500
2022-10-10 15:45:02 -04:00

80 lines
1.8 KiB
C

// REQUIRES: x86-registered-target
// RUN: %clang_cc1 %s -triple i386-apple-darwin10 -verify -fasm-blocks
// Disabling gnu inline assembly should have no effect on this testcase
// RUN: %clang_cc1 %s -triple i386-apple-darwin10 -verify -fasm-blocks -fno-gnu-inline-asm
#define M __asm int 0x2c
#define M2 int
void t1(void) { M }
void t2(void) { __asm int 2ch }
void t3(void) { __asm M2 2ch }
void t4(void) { __asm mov eax, fs:[10h] }
void t5(void) {
__asm {
int 0x2c ; } asm comments are fun! }{
}
__asm {}
}
int t6(void) {
__asm int 3 ; } comments for single-line asm
__asm {}
__asm int 4
return 10;
}
void t7(void) {
__asm {
push ebx
mov ebx, 07h
pop ebx
}
}
void t8(void) {
__asm nop __asm nop __asm nop
}
void t9(void) {
__asm nop __asm nop ; __asm nop
}
void t10(void) {
__asm {
mov eax, 0
__asm {
mov eax, 1
{
mov eax, 2
}
}
}
}
void t11(void) {
do { __asm mov eax, 0 __asm { __asm mov edx, 1 } } while(0);
}
void t12(void) {
__asm jmp label // expected-error {{use of undeclared label 'label'}}
}
void t13(void) {
__asm m{o}v eax, ebx // expected-error {{unknown token in expression}}
}
void t14(void) {
enum { A = 1, B };
__asm mov eax, offset A // expected-error {{offset operator cannot yet handle constants}}
}
// GH57791
typedef struct S {
unsigned bf1:1; // expected-note {{bit-field is declared here}}
unsigned bf2:1; // expected-note {{bit-field is declared here}}
} S;
void t15(S s) {
__asm {
mov eax, s.bf1 // expected-error {{an inline asm block cannot have an operand which is a bit-field}}
mov s.bf2, eax // expected-error {{an inline asm block cannot have an operand which is a bit-field}}
}
}
int t_fail(void) { // expected-note {{to match this}}
__asm
__asm { // expected-error 3 {{expected}} expected-note {{to match this}}