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compiler: disallow op= on mutable values (fix #835).

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In general, we can't reallocate a value in earlier stack frames,
or fixup references to it. This mainly impacts lists.
This commit is contained in:
whitequark 2017-10-02 01:55:17 +00:00
parent f86744c65c
commit e59b301a3b
2 changed files with 28 additions and 14 deletions
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30
artiq/compiler/validators/escape.py
View File

@ -298,8 +298,8 @@ class EscapeValidator(algorithm.Visitor):
# and exceptions can only refer to strings, so we don't actually check # and exceptions can only refer to strings, so we don't actually check
# this property. But we will need to, if string operations are ever added. # this property. But we will need to, if string operations are ever added.
def visit_assignment(self, target, value, is_aug_assign=False): def visit_assignment(self, target, value):
value_region = self._region_of(value) if not is_aug_assign else self.youngest_region value_region = self._region_of(value)
# If this is a variable, we might need to contract the live range. # If this is a variable, we might need to contract the live range.
if isinstance(value_region, Region): if isinstance(value_region, Region):
@ -316,19 +316,11 @@ class EscapeValidator(algorithm.Visitor):
target_regions = [self._region_of(name) for name in target_names] target_regions = [self._region_of(name) for name in target_names]
for target_region in target_regions: for target_region in target_regions:
if not Region.outlives(value_region, target_region): if not Region.outlives(value_region, target_region):
if is_aug_assign:
target_desc = "the assignment target, allocated here,"
else:
target_desc = "the assignment target"
note = diagnostic.Diagnostic("note",
"this expression has type {type}",
{"type": types.TypePrinter().name(value.type)},
value.loc)
diag = diagnostic.Diagnostic("error", diag = diagnostic.Diagnostic("error",
"the assigned value does not outlive the assignment target", {}, "the assigned value does not outlive the assignment target", {},
value.loc, [target.loc], value.loc, [target.loc],
notes=self._diagnostics_for(target_region, target.loc, notes=self._diagnostics_for(target_region, target.loc,
target_desc) + "the assignment target") +
self._diagnostics_for(value_region, value.loc, self._diagnostics_for(value_region, value.loc,
"the assigned value")) "the assigned value"))
self.engine.process(diag) self.engine.process(diag)
@ -339,9 +331,19 @@ class EscapeValidator(algorithm.Visitor):
def visit_AugAssign(self, node): def visit_AugAssign(self, node):
if builtins.is_allocated(node.target.type): if builtins.is_allocated(node.target.type):
# If the target is mutable, op-assignment will allocate note = diagnostic.Diagnostic("note",
# in the youngest region. "try using `{lhs} = {lhs} {op} {rhs}` instead",
self.visit_assignment(node.target, node.value, is_aug_assign=True) {"lhs": node.target.loc.source(),
"rhs": node.value.loc.source(),
"op": node.op.loc.source()[:-1]},
node.loc)
diag = diagnostic.Diagnostic("error",
"values cannot be mutated in-place", {},
node.op.loc, [node.target.loc],
notes=[note])
self.engine.process(diag)
self.visit_assignment(node.target, node.value)
def visit_Return(self, node): def visit_Return(self, node):
region = self._region_of(node.value) region = self._region_of(node.value)

12
artiq/test/lit/escape/error_mutable_aug_asgn.py Normal file
View File

@ -0,0 +1,12 @@
# RUN: %python -m artiq.compiler.testbench.embedding +diag %s 2>%t
# RUN: OutputCheck %s --file-to-check=%t
from artiq.experiment import *
@kernel
def entrypoint():
a = [1,2]
# CHECK-L: ${LINE:+2}: error: values cannot be mutated in-place
# CHECK-L: ${LINE:+1}: note: try using `a = a + [3,4]`
a += [3,4]