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Auto merge of #121282 - saethlin:gep-null-means-no-provenance, r=scot…
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…tmcm

Lower transmutes from int to pointer type as gep on null

I thought of this while looking at #121242. See that PR's description for why this lowering is preferable.

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 Mar 12, 2024
2 parents 5aad51d + 2eb9c6d commit 0fa7fea
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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 @@ -306,11 +306,11 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
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.ptradd(bx.const_null(bx.type_ptr()), imm),
(Pointer(..), Int(..)) => bx.ptrtoint(imm, to_backend_ty),
(F16 | F32 | F64 | F128, Pointer(..)) => {
let int_imm = bx.bitcast(imm, bx.cx().type_isize());
bx.inttoptr(int_imm, to_backend_ty)
bx.ptradd(bx.const_null(bx.type_ptr()), int_imm)
}
(Pointer(..), F16 | F32 | F64 | F128) => {
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, [[USIZE]] %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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