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Auto merge of #121282 - saethlin:gep-null-means-no-provenance, r=<try>
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Lower transmutes from int to pointer type as gep on null

I thought of this while looking at #121242

The UI test that's being changed here crashes without changing the transmutes into casts. Based on that, this PR should not be merged without a crater build-and-test run.
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bors committed Feb 19, 2024
2 parents 6122397 + 903dd09 commit d073071
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Showing 4 changed files with 8 additions and 8 deletions.
4 changes: 2 additions & 2 deletions compiler/rustc_codegen_ssa/src/mir/rvalue.rs
Original file line number Diff line number Diff line change
Expand Up @@ -305,11 +305,11 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
imm = match (from_scalar.primitive(), to_scalar.primitive()) {
(Int(..) | F32 | F64, Int(..) | F32 | F64) => bx.bitcast(imm, to_backend_ty),
(Pointer(..), Pointer(..)) => bx.pointercast(imm, to_backend_ty),
(Int(..), Pointer(..)) => bx.inttoptr(imm, to_backend_ty),
(Int(..), Pointer(..)) => bx.gep(bx.type_i8(), bx.const_null(bx.type_ptr()), &[imm]),
(Pointer(..), Int(..)) => bx.ptrtoint(imm, to_backend_ty),
(F32 | F64, Pointer(..)) => {
let int_imm = bx.bitcast(imm, bx.cx().type_isize());
bx.inttoptr(int_imm, to_backend_ty)
bx.gep(bx.type_i8(), bx.const_null(bx.type_ptr()), &[int_imm])
}
(Pointer(..), F32 | F64) => {
let int_imm = bx.ptrtoint(imm, bx.cx().type_isize());
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4 changes: 2 additions & 2 deletions tests/codegen/intrinsics/transmute.rs
Original file line number Diff line number Diff line change
Expand Up @@ -296,7 +296,7 @@ pub unsafe fn check_pair_with_bool(x: (u8, bool)) -> (bool, i8) {
pub unsafe fn check_float_to_pointer(x: f64) -> *const () {
// CHECK-NOT: alloca
// CHECK: %0 = bitcast double %x to i64
// CHECK: %_0 = inttoptr i64 %0 to ptr
// CHECK: %_0 = getelementptr i8, ptr null, i64 %0
// CHECK: ret ptr %_0
transmute(x)
}
Expand Down Expand Up @@ -371,7 +371,7 @@ pub unsafe fn check_issue_110005(x: (usize, bool)) -> Option<Box<[u8]>> {
// CHECK-LABEL: @check_pair_to_dst_ref(
#[no_mangle]
pub unsafe fn check_pair_to_dst_ref<'a>(x: (usize, usize)) -> &'a [u8] {
// CHECK: %_0.0 = inttoptr i64 %x.0 to ptr
// CHECK: %_0.0 = getelementptr i8, ptr null, i64 %x.0
// CHECK: %0 = insertvalue { ptr, i64 } poison, ptr %_0.0, 0
// CHECK: %1 = insertvalue { ptr, i64 } %0, i64 %x.1, 1
// CHECK: ret { ptr, i64 } %1
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2 changes: 1 addition & 1 deletion tests/codegen/transmute-scalar.rs
Original file line number Diff line number Diff line change
Expand Up @@ -49,7 +49,7 @@ pub fn ptr_to_int(p: *mut u16) -> usize {
}

// CHECK: define{{.*}}ptr @int_to_ptr([[USIZE]] %i)
// CHECK: %_0 = inttoptr [[USIZE]] %i to ptr
// CHECK: %_0 = getelementptr i8, ptr null, i64 %i
// CHECK-NEXT: ret ptr %_0
#[no_mangle]
pub fn int_to_ptr(i: usize) -> *mut u16 {
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6 changes: 3 additions & 3 deletions tests/ui/abi/foreign/foreign-call-no-runtime.rs
Original file line number Diff line number Diff line change
Expand Up @@ -40,21 +40,21 @@ pub fn main() {

extern "C" fn callback_isize(data: libc::uintptr_t) {
unsafe {
let data: *const isize = mem::transmute(data);
let data = data as *const isize;
assert_eq!(*data, 100);
}
}

extern "C" fn callback_i64(data: libc::uintptr_t) {
unsafe {
let data: *const i64 = mem::transmute(data);
let data = data as *const i64;
assert_eq!(*data, 100);
}
}

extern "C" fn callback_i32(data: libc::uintptr_t) {
unsafe {
let data: *const i32 = mem::transmute(data);
let data = data as *const i32;
assert_eq!(*data, 100);
}
}

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