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Rename local variables to clarify their purpose.

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This commit is contained in:
Dan Gohman
2018-07-26 11:09:11 -07:00
parent 15520fa961
commit e0124fa82f
1 changed files with 17 additions and 17 deletions
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34
lib/codegen/src/legalizer/heap.rs
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@@ -17,7 +17,7 @@ pub fn expand_heap_addr(
_isa: &TargetIsa,
) {
// Unpack the instruction.
let (heap, offset, size) = match func.dfg[inst] {
let (heap, offset, access_size) = match func.dfg[inst] {
ir::InstructionData::HeapAddr {
opcode,
heap,
@@ -32,10 +32,10 @@ pub fn expand_heap_addr(
match func.heaps[heap].style {
ir::HeapStyle::Dynamic { bound_gv } => {
dynamic_addr(inst, heap, offset, size, bound_gv, func)
dynamic_addr(inst, heap, offset, access_size, bound_gv, func)
}
ir::HeapStyle::Static { bound } => {
static_addr(inst, heap, offset, size, bound.into(), func, cfg)
static_addr(inst, heap, offset, access_size, bound.into(), func, cfg)
}
}
}
@@ -45,34 +45,34 @@ fn dynamic_addr(
inst: ir::Inst,
heap: ir::Heap,
offset: ir::Value,
size: u32,
access_size: u32,
bound_gv: ir::GlobalValue,
func: &mut ir::Function,
) {
let size = i64::from(size);
let access_size = i64::from(access_size);
let offset_ty = func.dfg.value_type(offset);
let addr_ty = func.dfg.value_type(func.dfg.first_result(inst));
let min_size = func.heaps[heap].min_size.into();
let mut pos = FuncCursor::new(func).at_inst(inst);
pos.use_srcloc(inst);
// Start with the bounds check. Trap if `offset + size > bound`.
// Start with the bounds check. Trap if `offset + access_size > bound`.
let bound = pos.ins().global_value(addr_ty, bound_gv);
let oob;
if size == 1 {
if access_size == 1 {
// `offset > bound - 1` is the same as `offset >= bound`.
oob = pos.ins()
.icmp(IntCC::UnsignedGreaterThanOrEqual, offset, bound);
} else if size <= min_size {
// We know that bound >= min_size, so here we can compare `offset > bound - size` without
} else if access_size <= min_size {
// We know that bound >= min_size, so here we can compare `offset > bound - access_size` without
// wrapping.
let adj_bound = pos.ins().iadd_imm(bound, -size);
let adj_bound = pos.ins().iadd_imm(bound, -access_size);
oob = pos.ins()
.icmp(IntCC::UnsignedGreaterThan, offset, adj_bound);
} else {
// We need an overflow check for the adjusted offset.
let size_val = pos.ins().iconst(offset_ty, size);
let (adj_offset, overflow) = pos.ins().iadd_cout(offset, size_val);
let access_size_val = pos.ins().iconst(offset_ty, access_size);
let (adj_offset, overflow) = pos.ins().iadd_cout(offset, access_size_val);
pos.ins().trapnz(overflow, ir::TrapCode::HeapOutOfBounds);
oob = pos.ins()
.icmp(IntCC::UnsignedGreaterThan, adj_offset, bound);
@@ -87,19 +87,19 @@ fn static_addr(
inst: ir::Inst,
heap: ir::Heap,
offset: ir::Value,
size: u32,
access_size: u32,
bound: i64,
func: &mut ir::Function,
cfg: &mut ControlFlowGraph,
) {
let size = i64::from(size);
let access_size = i64::from(access_size);
let offset_ty = func.dfg.value_type(offset);
let addr_ty = func.dfg.value_type(func.dfg.first_result(inst));
let mut pos = FuncCursor::new(func).at_inst(inst);
pos.use_srcloc(inst);
// Start with the bounds check. Trap if `offset + size > bound`.
if size > bound {
// Start with the bounds check. Trap if `offset + access_size > bound`.
if access_size > bound {
// This will simply always trap since `offset >= 0`.
pos.ins().trap(ir::TrapCode::HeapOutOfBounds);
pos.func.dfg.replace(inst).iconst(addr_ty, 0);
@@ -114,7 +114,7 @@ fn static_addr(
}
// Check `offset > limit` which is now known non-negative.
let limit = bound - size;
let limit = bound - access_size;
// We may be able to omit the check entirely for 32-bit offsets if the heap bound is 4 GB or
// more.