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compiler: only allow constant exception messages 

Otherwise, the exception message might be allocated on a stack, and will
become a dangling pointer when the exception is raised.
This will break some code that constructs exceptions with a function by
passing the message as a parameter because we cannot know if the parameter
is a constant. A way to mitigate this would be to defer this check to
LLVM IR codegen stage, and do inlining first for those exception
allocation functions, but I am not sure if we will guarantee inlining
for certain functions, and whether this is really needed.
This commit is contained in:
pca006132 2022-01-27 23:03:28 +08:00 committed by Sébastien Bourdeauducq
parent 234a82aaa9
commit 93328ad8ee
1 changed files with 13 additions and 3 deletions
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16
artiq/compiler/transforms/artiq_ir_generator.py
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@ -2198,7 +2198,8 @@ class ARTIQIRGenerator(algorithm.Visitor):
return phi
# Keep this function with builtins.TException.attributes.
def alloc_exn(self, typ, message=None, param0=None, param1=None, param2=None):
def alloc_exn(self, typ, message=None, param0=None, param1=None,
param2=None, nomsgcheck=False):
typ = typ.find()
name = "{}:{}".format(typ.id, typ.name)
name_id = self.embedding_map.store_str(name)
@ -2212,8 +2213,16 @@ class ARTIQIRGenerator(algorithm.Visitor):
if message is None:
attributes.append(ir.Constant(typ.name, builtins.TStr()))
elif isinstance(message, ir.Constant) or nomsgcheck:
attributes.append(message) # message
else:
attributes.append(message) # message
diag = diagnostic.Diagnostic(
"error",
"only constant exception messages are supported",
{},
self.current_loc if message.loc is None else message.loc
)
self.engine.process(diag)
param_type = builtins.TInt64()
for param in [param0, param1, param2]:
@ -2674,7 +2683,8 @@ class ARTIQIRGenerator(algorithm.Visitor):
old_final_branch, self.final_branch = self.final_branch, None
old_unwind, self.unwind_target = self.unwind_target, None
exn = self.alloc_exn(builtins.TException("AssertionError"), message=msg)
exn = self.alloc_exn(builtins.TException("AssertionError"),
message=msg, nomsgcheck=True)
self.append(ir.SetAttr(exn, "#__file__", file))
self.append(ir.SetAttr(exn, "#__line__", line))
self.append(ir.SetAttr(exn, "#__col__", col))