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Make negative and too-far shifts have defined behavior.

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This commit is contained in:
whitequark 2015-07-23 00:58:41 +03:00
parent bf60978c7b
commit 4cfe4ea148
3 changed files with 24 additions and 6 deletions
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10
artiq/compiler/transforms/artiq_ir_generator.py
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@ -900,8 +900,14 @@ class ARTIQIRGenerator(algorithm.Visitor):
def visit_BinOpT(self, node):
if builtins.is_numeric(node.type):
# TODO: check for division by zero
# TODO: check for shift by too many bits
return self.append(ir.Arith(node.op, self.visit(node.left), self.visit(node.right)))
rhs = self.visit(node.right)
if isinstance(node.op, (ast.LShift, ast.RShift)):
# Check for negative shift amount.
self._make_check(self.append(ir.Compare(ast.GtE(loc=None), rhs,
ir.Constant(0, rhs.type))),
lambda: self.append(ir.Alloc([], builtins.TValueError())))
return self.append(ir.Arith(node.op, self.visit(node.left), rhs))
elif isinstance(node.op, ast.Add): # list + list, tuple + tuple
lhs, rhs = self.visit(node.left), self.visit(node.right)
if types.is_tuple(node.left.type) and types.is_tuple(node.right.type):

18
artiq/compiler/transforms/llvm_ir_generator.py
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@ -368,11 +368,21 @@ class LLVMIRGenerator:
return self.llbuilder.fptosi(llvalue, self.llty_of_type(insn.type),
name=insn.name)
elif isinstance(insn.op, ast.LShift):
return self.llbuilder.shl(self.map(insn.lhs()), self.map(insn.rhs()),
name=insn.name)
lllhs, llrhs = map(self.map, (insn.lhs(), insn.rhs()))
llrhs_max = ll.Constant(llrhs.type, builtins.get_int_width(insn.lhs().type))
llrhs_overflow = self.llbuilder.icmp_signed('>=', llrhs, llrhs_max)
llvalue_zero = ll.Constant(lllhs.type, 0)
llvalue = self.llbuilder.shl(lllhs, llrhs)
return self.llbuilder.select(llrhs_overflow, llvalue_zero, llvalue,
name=insn.name)
elif isinstance(insn.op, ast.RShift):
return self.llbuilder.ashr(self.map(insn.lhs()), self.map(insn.rhs()),
name=insn.name)
lllhs, llrhs = map(self.map, (insn.lhs(), insn.rhs()))
llrhs_max = ll.Constant(llrhs.type, builtins.get_int_width(insn.lhs().type) - 1)
llrhs_overflow = self.llbuilder.icmp_signed('>', llrhs, llrhs_max)
llvalue = self.llbuilder.ashr(lllhs, llrhs)
llvalue_max = self.llbuilder.ashr(lllhs, llrhs_max) # preserve sign bit
return self.llbuilder.select(llrhs_overflow, llvalue_max, llvalue,
name=insn.name)
elif isinstance(insn.op, ast.BitAnd):
return self.llbuilder.and_(self.map(insn.lhs()), self.map(insn.rhs()),
name=insn.name)

2
lit-test/compiler/integration/arithmetics.py
View File

@ -28,6 +28,8 @@ assert 9.0 ** 0.5 == 3.0
assert 1 << 1 == 2
assert 2 >> 1 == 1
assert -2 >> 1 == -1
assert 1 << 32 == 0
assert -1 >> 32 == -1
assert 0x18 & 0x0f == 0x08
assert 0x18 | 0x0f == 0x1f
assert 0x18 ^ 0x0f == 0x17