[Frontend] Revert deep copy when entering new scope (triton-lang#8832)

This was added when we were attempting to support mutations in the
frontend. However, now that we ban mutations it's nothing but an added
cost during compilation.

With this change I see a 250ms improvement in compilation time for the
attention gluon example kernel.

Author: peterbell10

python/test/unit/language/test_frontend.py

@@ -152,9 +152,6 @@ class TypeWithBuiltinInitializer:
     def __init__(self, _semantic=None):
         self.value = tl.arange(0, 4, _semantic=_semantic)
 
-    def modify(self, value, _semantic=None):
-        self.value = value
-
 
 @filecheck_test
 @triton.jit
@@ -164,48 +161,6 @@ def test_aggregate_initializers():
     # CHECK: [[RANGE:%.*]] = tt.make_range {end = 4 : i32, start = 0 : i32}
     # CHECK: call @{{.*}}anchor{{.*}}([[RANGE]])
     anchor(value)
-    # CHECK: [[RANGE:%.*]] = tt.make_range {end = 8 : i32, start = 4 : i32}
-    # CHECK: call @{{.*}}anchor{{.*}}([[RANGE]])
-    value.modify(tl.arange(4, 8))
-    anchor(value)
-
-
-@filecheck_test
-@triton.jit
-def test_aggregate_modification_in_for_loop():
-    # CHECK-LABEL: test_aggregate_modification_in_for_loop
-    value = TypeWithBuiltinInitializer()
-    # CHECK: [[RANGE:%.*]] = tt.make_range {end = 4 : i32, start = 0 : i32}
-    for i in range(0, 2):
-        # CHECK: [[RET:%.*]] = scf.for
-        # CHECK-SAME: iter_args([[ITER:%.*]] = [[RANGE]])
-        value.modify(tl.arange(4, 8))
-        # CHECK: [[RANGE:%.*]] = tt.make_range {end = 8 : i32, start = 4 : i32}
-        # CHECK: yield [[RANGE]]
-
-    anchor(value)
-    # CHECK: call @{{.*}}anchor{{.*}}([[RET]])
-
-
-@filecheck_test
-@triton.jit
-def test_aggregate_modification_in_while_loop():
-    # CHECK-LABEL: test_aggregate_modification_in_while_loop
-    value = TypeWithBuiltinInitializer()
-    # CHECK: [[RANGE:%.*]] = tt.make_range {end = 4 : i32, start = 0 : i32}
-    i = 0
-    # CHECK: [[C0:%.*]] = arith.constant 0 :
-    while i < 1:
-        # CHECK: [[RET:%.*]]:2 = scf.while ([[ITER:%.*]] = [[RANGE]], [[IV:%.*]] = [[C0]])
-        # CHECK: do
-        i = 1
-        # CHECK: [[C1:%.*]] = arith.constant 1 :
-        value.modify(tl.arange(4, 8))
-        # CHECK: [[RANGE:%.*]] = tt.make_range {end = 8 : i32, start = 4 : i32}
-        # CHECK: yield [[RANGE]], [[C1]]
-
-    anchor(value)
-    # CHECK: call @{{.*}}anchor{{.*}}([[RET]]#0)
 
 
 @triton.jit

python/triton/compiler/code_generator.py

@@ -110,26 +110,15 @@ def unflatten_ir_values(handles: List[ir.value], types: List[base_type]):
 _condition_types = {bool, int, type(None)}  # Python types accepted for conditionals inside kernels
 
 
-def _clone_triton_value(val):
-    handles = []
-    val._flatten_ir(handles)
-    clone, _ = val.type._unflatten_ir(handles, 0)
-    return clone
-
-
-def _clone_scope(scope):
-    return {name: _clone_triton_value(val) if _is_triton_value(val) else val for name, val in scope.items()}
-
-
 class enter_sub_region:
 
     def __init__(self, generator):
         self.generator = generator
 
     def __enter__(self):
         # record lscope & local_defs in the parent scope
-        self.liveins = _clone_scope(self.generator.lscope)
-        self.prev_defs = _clone_scope(self.generator.local_defs)
+        self.liveins = dict(self.generator.lscope)
+        self.prev_defs = dict(self.generator.local_defs)
         self.generator.local_defs = {}
         self.insert_block = self.generator.builder.get_insertion_block()
         self.insert_point = self.generator.builder.get_insertion_point()