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assume value ranges in transmute

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Fixes #109958
This commit is contained in:
Scott McMurray 2023-04-06 00:36:36 -07:00
parent d8fc819247
commit 1bcb0ec28c
4 changed files with 253 additions and 16 deletions
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63
compiler/rustc_codegen_ssa/src/mir/rvalue.rs
View File

@ -12,6 +12,7 @@ use rustc_middle::mir::Operand;
use rustc_middle::ty::cast::{CastTy, IntTy};
use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, TyAndLayout};
use rustc_middle::ty::{self, adjustment::PointerCast, Instance, Ty, TyCtxt};
use rustc_session::config::OptLevel;
use rustc_span::source_map::{Span, DUMMY_SP};
use rustc_target::abi::{self, FIRST_VARIANT};
@ -231,10 +232,16 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
(ScalarOrZst::Scalar(in_scalar), ScalarOrZst::Scalar(out_scalar))
if in_scalar.size(self.cx) == out_scalar.size(self.cx) =>
{
let operand_bty = bx.backend_type(operand.layout);
let cast_bty = bx.backend_type(cast);
Some(OperandValue::Immediate(
self.transmute_immediate(bx, imm, in_scalar, out_scalar, cast_bty),
))
Some(OperandValue::Immediate(self.transmute_immediate(
bx,
imm,
in_scalar,
operand_bty,
out_scalar,
cast_bty,
)))
}
_ => None,
}
@ -250,11 +257,13 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
&& in_a.size(self.cx) == out_a.size(self.cx)
&& in_b.size(self.cx) == out_b.size(self.cx)
{
let in_a_ibty = bx.scalar_pair_element_backend_type(operand.layout, 0, false);
let in_b_ibty = bx.scalar_pair_element_backend_type(operand.layout, 1, false);
let out_a_ibty = bx.scalar_pair_element_backend_type(cast, 0, false);
let out_b_ibty = bx.scalar_pair_element_backend_type(cast, 1, false);
Some(OperandValue::Pair(
self.transmute_immediate(bx, imm_a, in_a, out_a, out_a_ibty),
self.transmute_immediate(bx, imm_b, in_b, out_b, out_b_ibty),
self.transmute_immediate(bx, imm_a, in_a, in_a_ibty, out_a, out_a_ibty),
self.transmute_immediate(bx, imm_b, in_b, in_b_ibty, out_b, out_b_ibty),
))
} else {
None
@ -273,6 +282,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
bx: &mut Bx,
mut imm: Bx::Value,
from_scalar: abi::Scalar,
from_backend_ty: Bx::Type,
to_scalar: abi::Scalar,
to_backend_ty: Bx::Type,
) -> Bx::Value {
@ -280,6 +290,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
use abi::Primitive::*;
imm = bx.from_immediate(imm);
self.assume_scalar_range(bx, imm, from_scalar, from_backend_ty);
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),
@ -294,10 +305,52 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
bx.bitcast(int_imm, to_backend_ty)
}
};
self.assume_scalar_range(bx, imm, to_scalar, to_backend_ty);
imm = bx.to_immediate_scalar(imm, to_scalar);
imm
}
fn assume_scalar_range(
&self,
bx: &mut Bx,
imm: Bx::Value,
scalar: abi::Scalar,
backend_ty: Bx::Type,
) {
if matches!(self.cx.sess().opts.optimize, OptLevel::No | OptLevel::Less)
|| !matches!(scalar.primitive(), abi::Primitive::Int(..))
|| scalar.is_always_valid(self.cx)
{
return;
}
let abi::WrappingRange { start, end } = scalar.valid_range(self.cx);
if start <= end {
if start > 0 {
let low = bx.const_uint_big(backend_ty, start);
let cmp = bx.icmp(IntPredicate::IntUGE, imm, low);
bx.assume(cmp);
}
let type_max = scalar.size(self.cx).unsigned_int_max();
if end < type_max {
let high = bx.const_uint_big(backend_ty, end);
let cmp = bx.icmp(IntPredicate::IntULE, imm, high);
bx.assume(cmp);
}
} else {
let low = bx.const_uint_big(backend_ty, start);
let cmp_low = bx.icmp(IntPredicate::IntUGE, imm, low);
let high = bx.const_uint_big(backend_ty, end);
let cmp_high = bx.icmp(IntPredicate::IntULE, imm, high);
let or = bx.or(cmp_low, cmp_high);
bx.assume(or);
}
}
pub fn codegen_rvalue_unsized(
&mut self,
bx: &mut Bx,

184
tests/codegen/intrinsics/transmute-niched.rs Normal file
View File

@ -0,0 +1,184 @@
// revisions: OPT DBG
// [OPT] compile-flags: -C opt-level=3 -C no-prepopulate-passes
// [DBG] compile-flags: -C opt-level=0 -C no-prepopulate-passes
// only-64bit (so I don't need to worry about usize)
// min-llvm-version: 15.0 # this test assumes `ptr`s
#![crate_type = "lib"]
use std::mem::transmute;
use std::num::NonZeroU32;
#[repr(u8)]
pub enum SmallEnum {
A = 10,
B = 11,
C = 12,
}
// CHECK-LABEL: @check_to_enum(
#[no_mangle]
pub unsafe fn check_to_enum(x: i8) -> SmallEnum {
// OPT: %0 = icmp uge i8 %x, 10
// OPT: call void @llvm.assume(i1 %0)
// OPT: %1 = icmp ule i8 %x, 12
// OPT: call void @llvm.assume(i1 %1)
// DBG-NOT: icmp
// DBG-NOT: assume
// CHECK: ret i8 %x
transmute(x)
}
// CHECK-LABEL: @check_from_enum(
#[no_mangle]
pub unsafe fn check_from_enum(x: SmallEnum) -> i8 {
// OPT: %0 = icmp uge i8 %x, 10
// OPT: call void @llvm.assume(i1 %0)
// OPT: %1 = icmp ule i8 %x, 12
// OPT: call void @llvm.assume(i1 %1)
// DBG-NOT: icmp
// DBG-NOT: assume
// CHECK: ret i8 %x
transmute(x)
}
// CHECK-LABEL: @check_to_ordering(
#[no_mangle]
pub unsafe fn check_to_ordering(x: u8) -> std::cmp::Ordering {
// OPT: %0 = icmp uge i8 %x, -1
// OPT: %1 = icmp ule i8 %x, 1
// OPT: %2 = or i1 %0, %1
// OPT: call void @llvm.assume(i1 %2)
// DBG-NOT: icmp
// DBG-NOT: assume
// CHECK: ret i8 %x
transmute(x)
}
// CHECK-LABEL: @check_from_ordering(
#[no_mangle]
pub unsafe fn check_from_ordering(x: std::cmp::Ordering) -> u8 {
// OPT: %0 = icmp uge i8 %x, -1
// OPT: %1 = icmp ule i8 %x, 1
// OPT: %2 = or i1 %0, %1
// OPT: call void @llvm.assume(i1 %2)
// DBG-NOT: icmp
// DBG-NOT: assume
// CHECK: ret i8 %x
transmute(x)
}
#[repr(i32)]
pub enum Minus100ToPlus100 {
A = -100,
B = -90,
C = -80,
D = -70,
E = -60,
F = -50,
G = -40,
H = -30,
I = -20,
J = -10,
K = 0,
L = 10,
M = 20,
N = 30,
O = 40,
P = 50,
Q = 60,
R = 70,
S = 80,
T = 90,
U = 100,
}
// CHECK-LABEL: @check_enum_from_char(
#[no_mangle]
pub unsafe fn check_enum_from_char(x: char) -> Minus100ToPlus100 {
// OPT: %0 = icmp ule i32 %x, 1114111
// OPT: call void @llvm.assume(i1 %0)
// OPT: %1 = icmp uge i32 %x, -100
// OPT: %2 = icmp ule i32 %x, 100
// OPT: %3 = or i1 %1, %2
// OPT: call void @llvm.assume(i1 %3)
// DBG-NOT: icmp
// DBG-NOT: assume
// CHECK: ret i32 %x
transmute(x)
}
// CHECK-LABEL: @check_enum_to_char(
#[no_mangle]
pub unsafe fn check_enum_to_char(x: Minus100ToPlus100) -> char {
// OPT: %0 = icmp uge i32 %x, -100
// OPT: %1 = icmp ule i32 %x, 100
// OPT: %2 = or i1 %0, %1
// OPT: call void @llvm.assume(i1 %2)
// OPT: %3 = icmp ule i32 %x, 1114111
// OPT: call void @llvm.assume(i1 %3)
// DBG-NOT: icmp
// DBG-NOT: assume
// CHECK: ret i32 %x
transmute(x)
}
// CHECK-LABEL: @check_swap_pair(
#[no_mangle]
pub unsafe fn check_swap_pair(x: (char, NonZeroU32)) -> (NonZeroU32, char) {
// OPT: %0 = icmp ule i32 %x.0, 1114111
// OPT: call void @llvm.assume(i1 %0)
// OPT: %1 = icmp uge i32 %x.0, 1
// OPT: call void @llvm.assume(i1 %1)
// OPT: %2 = icmp uge i32 %x.1, 1
// OPT: call void @llvm.assume(i1 %2)
// OPT: %3 = icmp ule i32 %x.1, 1114111
// OPT: call void @llvm.assume(i1 %3)
// DBG-NOT: icmp
// DBG-NOT: assume
// CHECK: %[[P1:.+]] = insertvalue { i32, i32 } poison, i32 %x.0, 0
// CHECK: %[[P2:.+]] = insertvalue { i32, i32 } %[[P1]], i32 %x.1, 1
// CHECK: ret { i32, i32 } %[[P2]]
transmute(x)
}
// CHECK-LABEL: @check_bool_from_ordering(
#[no_mangle]
pub unsafe fn check_bool_from_ordering(x: std::cmp::Ordering) -> bool {
// OPT: %0 = icmp uge i8 %x, -1
// OPT: %1 = icmp ule i8 %x, 1
// OPT: %2 = or i1 %0, %1
// OPT: call void @llvm.assume(i1 %2)
// OPT: %3 = icmp ule i8 %x, 1
// OPT: call void @llvm.assume(i1 %3)
// DBG-NOT: icmp
// DBG-NOT: assume
// CHECK: %[[R:.+]] = trunc i8 %x to i1
// CHECK: ret i1 %[[R]]
transmute(x)
}
// CHECK-LABEL: @check_bool_to_ordering(
#[no_mangle]
pub unsafe fn check_bool_to_ordering(x: bool) -> std::cmp::Ordering {
// CHECK: %0 = zext i1 %x to i8
// OPT: %1 = icmp ule i8 %0, 1
// OPT: call void @llvm.assume(i1 %1)
// OPT: %2 = icmp uge i8 %0, -1
// OPT: %3 = icmp ule i8 %0, 1
// OPT: %4 = or i1 %2, %3
// OPT: call void @llvm.assume(i1 %4)
// DBG-NOT: icmp
// DBG-NOT: assume
// CHECK: ret i8 %0
transmute(x)
}

8
tests/codegen/intrinsics/transmute.rs
View File

@ -169,8 +169,8 @@ pub unsafe fn check_aggregate_from_bool(x: bool) -> Aggregate8 {
#[no_mangle]
pub unsafe fn check_byte_to_bool(x: u8) -> bool {
// CHECK-NOT: alloca
// CHECK: %0 = trunc i8 %x to i1
// CHECK: ret i1 %0
// CHECK: %[[R:.+]] = trunc i8 %x to i1
// CHECK: ret i1 %[[R]]
transmute(x)
}
@ -178,8 +178,8 @@ pub unsafe fn check_byte_to_bool(x: u8) -> bool {
#[no_mangle]
pub unsafe fn check_byte_from_bool(x: bool) -> u8 {
// CHECK-NOT: alloca
// CHECK: %0 = zext i1 %x to i8
// CHECK: ret i8 %0
// CHECK: %[[R:.+]] = zext i1 %x to i8
// CHECK: ret i8 %[[R:.+]]
transmute(x)
}

14
tests/codegen/transmute-scalar.rs
View File

@ -1,4 +1,4 @@
// compile-flags: -O -C no-prepopulate-passes
// compile-flags: -C opt-level=0 -C no-prepopulate-passes
// min-llvm-version: 15.0 # this test assumes `ptr`s and thus no `pointercast`s
#![crate_type = "lib"]
@ -10,7 +10,7 @@
// However, `bitcast`s and `ptrtoint`s and `inttoptr`s are still worth doing when
// that allows us to avoid the `alloca`s entirely; see `rvalue_creates_operand`.
// CHECK-LABEL: define{{.*}}i32 @f32_to_bits(float noundef %x)
// CHECK-LABEL: define{{.*}}i32 @f32_to_bits(float %x)
// CHECK: %0 = bitcast float %x to i32
// CHECK-NEXT: ret i32 %0
#[no_mangle]
@ -18,7 +18,7 @@ pub fn f32_to_bits(x: f32) -> u32 {
unsafe { std::mem::transmute(x) }
}
// CHECK-LABEL: define{{.*}}i8 @bool_to_byte(i1 noundef zeroext %b)
// CHECK-LABEL: define{{.*}}i8 @bool_to_byte(i1 zeroext %b)
// CHECK: %0 = zext i1 %b to i8
// CHECK-NEXT: ret i8 %0
#[no_mangle]
@ -26,7 +26,7 @@ pub fn bool_to_byte(b: bool) -> u8 {
unsafe { std::mem::transmute(b) }
}
// CHECK-LABEL: define{{.*}}noundef zeroext i1 @byte_to_bool(i8 noundef %byte)
// CHECK-LABEL: define{{.*}}zeroext i1 @byte_to_bool(i8 %byte)
// CHECK: %0 = trunc i8 %byte to i1
// CHECK-NEXT: ret i1 %0
#[no_mangle]
@ -34,14 +34,14 @@ pub unsafe fn byte_to_bool(byte: u8) -> bool {
std::mem::transmute(byte)
}
// CHECK-LABEL: define{{.*}}ptr @ptr_to_ptr(ptr noundef %p)
// CHECK-LABEL: define{{.*}}ptr @ptr_to_ptr(ptr %p)
// CHECK: ret ptr %p
#[no_mangle]
pub fn ptr_to_ptr(p: *mut u16) -> *mut u8 {
unsafe { std::mem::transmute(p) }
}
// CHECK: define{{.*}}[[USIZE:i[0-9]+]] @ptr_to_int(ptr noundef %p)
// CHECK: define{{.*}}[[USIZE:i[0-9]+]] @ptr_to_int(ptr %p)
// CHECK: %0 = ptrtoint ptr %p to [[USIZE]]
// CHECK-NEXT: ret [[USIZE]] %0
#[no_mangle]
@ -49,7 +49,7 @@ pub fn ptr_to_int(p: *mut u16) -> usize {
unsafe { std::mem::transmute(p) }
}
// CHECK: define{{.*}}ptr @int_to_ptr([[USIZE]] noundef %i)
// CHECK: define{{.*}}ptr @int_to_ptr([[USIZE]] %i)
// CHECK: %0 = inttoptr [[USIZE]] %i to ptr
// CHECK-NEXT: ret ptr %0
#[no_mangle]