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Move shifting code out of expr and into somewhere more accessible

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This commit is contained in:
Niko Matsakis 2015-10-21 17:35:15 -04:00
parent 81ff2c2f8e
commit 877b93add2
3 changed files with 88 additions and 63 deletions
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12
src/librustc_trans/trans/base.rs
View file

@ -75,6 +75,7 @@ use trans::intrinsic;
use trans::machine;
use trans::machine::{llsize_of, llsize_of_real};
use trans::meth;
use trans::mir;
use trans::monomorphize;
use trans::tvec;
use trans::type_::Type;
@ -1231,7 +1232,10 @@ pub fn new_fn_ctxt<'a, 'tcx>(ccx: &'a CrateContext<'a, 'tcx>,
false
};
let mir = ccx.mir_map().get(&id);
let mut fcx = FunctionContext {
mir: mir,
llfn: llfndecl,
llenv: None,
llretslotptr: Cell::new(None),
@ -1571,7 +1575,7 @@ pub fn trans_closure<'a, 'b, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
llfndecl: ValueRef,
param_substs: &'tcx Substs<'tcx>,
fn_ast_id: ast::NodeId,
_attributes: &[ast::Attribute],
attributes: &[ast::Attribute],
output_type: ty::FnOutput<'tcx>,
abi: Abi,
closure_env: closure::ClosureEnv<'b>) {
@ -1600,6 +1604,12 @@ pub fn trans_closure<'a, 'b, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
&arena);
let mut bcx = init_function(&fcx, false, output_type);
if attributes.iter().any(|item| item.check_name("rustc_mir")) {
mir::trans_mir(bcx);
fcx.cleanup();
return;
}
// cleanup scope for the incoming arguments
let fn_cleanup_debug_loc =
debuginfo::get_cleanup_debug_loc_for_ast_node(ccx, fn_ast_id, body.span, true);

78
src/librustc_trans/trans/common.rs
View file

@ -16,7 +16,7 @@ pub use self::ExprOrMethodCall::*;
use session::Session;
use llvm;
use llvm::{ValueRef, BasicBlockRef, BuilderRef, ContextRef};
use llvm::{ValueRef, BasicBlockRef, BuilderRef, ContextRef, TypeKind};
use llvm::{True, False, Bool};
use middle::cfg;
use middle::def;
@ -40,6 +40,7 @@ use middle::traits;
use middle::ty::{self, HasTypeFlags, Ty};
use middle::ty::fold::{TypeFolder, TypeFoldable};
use rustc_front::hir;
use rustc_mir::repr::Mir;
use util::nodemap::{FnvHashMap, NodeMap};
use arena::TypedArena;
@ -328,6 +329,11 @@ impl<'tcx> DropFlagHintsMap<'tcx> {
// Function context. Every LLVM function we create will have one of
// these.
pub struct FunctionContext<'a, 'tcx: 'a> {
// The MIR for this function. At present, this is optional because
// we only have MIR available for things that are local to the
// crate.
pub mir: Option<&'a Mir<'tcx>>,
// The ValueRef returned from a call to llvm::LLVMAddFunction; the
// address of the first instruction in the sequence of
// instructions for this function that will go in the .text
@ -407,6 +413,10 @@ pub struct FunctionContext<'a, 'tcx: 'a> {
}
impl<'a, 'tcx> FunctionContext<'a, 'tcx> {
pub fn mir(&self) -> &'a Mir<'tcx> {
self.mir.unwrap()
}
pub fn arg_offset(&self) -> usize {
self.env_arg_pos() + if self.llenv.is_some() { 1 } else { 0 }
}
@ -644,6 +654,10 @@ impl<'blk, 'tcx> BlockS<'blk, 'tcx> {
}
pub fn sess(&self) -> &'blk Session { self.fcx.ccx.sess() }
pub fn mir(&self) -> &'blk Mir<'tcx> {
self.fcx.mir()
}
pub fn name(&self, name: ast::Name) -> String {
name.to_string()
}
@ -1132,3 +1146,65 @@ pub fn inlined_variant_def<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
ccx.sess().bug(&format!("no variant for {:?}::{}", adt_def, inlined_vid))
})
}
// To avoid UB from LLVM, these two functions mask RHS with an
// appropriate mask unconditionally (i.e. the fallback behavior for
// all shifts). For 32- and 64-bit types, this matches the semantics
// of Java. (See related discussion on #1877 and #10183.)
pub fn build_unchecked_lshift<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
lhs: ValueRef,
rhs: ValueRef,
binop_debug_loc: DebugLoc) -> ValueRef {
let rhs = base::cast_shift_expr_rhs(bcx, hir::BinOp_::BiShl, lhs, rhs);
// #1877, #10183: Ensure that input is always valid
let rhs = shift_mask_rhs(bcx, rhs, binop_debug_loc);
build::Shl(bcx, lhs, rhs, binop_debug_loc)
}
pub fn build_unchecked_rshift<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
lhs_t: Ty<'tcx>,
lhs: ValueRef,
rhs: ValueRef,
binop_debug_loc: DebugLoc) -> ValueRef {
let rhs = base::cast_shift_expr_rhs(bcx, hir::BinOp_::BiShr, lhs, rhs);
// #1877, #10183: Ensure that input is always valid
let rhs = shift_mask_rhs(bcx, rhs, binop_debug_loc);
let is_signed = lhs_t.is_signed();
if is_signed {
build::AShr(bcx, lhs, rhs, binop_debug_loc)
} else {
build::LShr(bcx, lhs, rhs, binop_debug_loc)
}
}
fn shift_mask_rhs<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
rhs: ValueRef,
debug_loc: DebugLoc) -> ValueRef {
let rhs_llty = val_ty(rhs);
build::And(bcx, rhs, shift_mask_val(bcx, rhs_llty, rhs_llty, false), debug_loc)
}
pub fn shift_mask_val<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
llty: Type,
mask_llty: Type,
invert: bool) -> ValueRef {
let kind = llty.kind();
match kind {
TypeKind::Integer => {
// i8/u8 can shift by at most 7, i16/u16 by at most 15, etc.
let val = llty.int_width() - 1;
if invert {
C_integral(mask_llty, !val, true)
} else {
C_integral(mask_llty, val, false)
}
},
TypeKind::Vector => {
let mask = shift_mask_val(bcx, llty.element_type(), mask_llty.element_type(), invert);
build::VectorSplat(bcx, mask_llty.vector_length(), mask)
},
_ => panic!("shift_mask_val: expected Integer or Vector, found {:?}", kind),
}
}

61
src/librustc_trans/trans/expr.rs
View file

@ -2574,29 +2574,6 @@ impl OverflowOpViaInputCheck {
}
}
fn shift_mask_val<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
llty: Type,
mask_llty: Type,
invert: bool) -> ValueRef {
let kind = llty.kind();
match kind {
TypeKind::Integer => {
// i8/u8 can shift by at most 7, i16/u16 by at most 15, etc.
let val = llty.int_width() - 1;
if invert {
C_integral(mask_llty, !val, true)
} else {
C_integral(mask_llty, val, false)
}
},
TypeKind::Vector => {
let mask = shift_mask_val(bcx, llty.element_type(), mask_llty.element_type(), invert);
VectorSplat(bcx, mask_llty.vector_length(), mask)
},
_ => panic!("shift_mask_val: expected Integer or Vector, found {:?}", kind),
}
}
// Check if an integer or vector contains a nonzero element.
fn build_nonzero_check<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
value: ValueRef,
@ -2616,44 +2593,6 @@ fn build_nonzero_check<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
}
}
// To avoid UB from LLVM, these two functions mask RHS with an
// appropriate mask unconditionally (i.e. the fallback behavior for
// all shifts). For 32- and 64-bit types, this matches the semantics
// of Java. (See related discussion on #1877 and #10183.)
fn build_unchecked_lshift<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
lhs: ValueRef,
rhs: ValueRef,
binop_debug_loc: DebugLoc) -> ValueRef {
let rhs = base::cast_shift_expr_rhs(bcx, hir::BinOp_::BiShl, lhs, rhs);
// #1877, #10183: Ensure that input is always valid
let rhs = shift_mask_rhs(bcx, rhs, binop_debug_loc);
Shl(bcx, lhs, rhs, binop_debug_loc)
}
fn build_unchecked_rshift<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
lhs_t: Ty<'tcx>,
lhs: ValueRef,
rhs: ValueRef,
binop_debug_loc: DebugLoc) -> ValueRef {
let rhs = base::cast_shift_expr_rhs(bcx, hir::BinOp_::BiShr, lhs, rhs);
// #1877, #10183: Ensure that input is always valid
let rhs = shift_mask_rhs(bcx, rhs, binop_debug_loc);
let is_signed = lhs_t.is_signed();
if is_signed {
AShr(bcx, lhs, rhs, binop_debug_loc)
} else {
LShr(bcx, lhs, rhs, binop_debug_loc)
}
}
fn shift_mask_rhs<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
rhs: ValueRef,
debug_loc: DebugLoc) -> ValueRef {
let rhs_llty = val_ty(rhs);
And(bcx, rhs, shift_mask_val(bcx, rhs_llty, rhs_llty, false), debug_loc)
}
fn with_overflow_check<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, oop: OverflowOp, info: NodeIdAndSpan,
lhs_t: Ty<'tcx>, lhs: ValueRef,
rhs: ValueRef,