usb-tools/amaranth
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

hdl.ast: simplify {bit,word}_select with constant offset.

Browse source 
We don't have any other convenient shortcut for x[off*w:(off+1)*w],
but using word_select to extract a single static range would result
in severe bloat of emitted code through expansion to dead branches.
Recognize and simplify this pattern.
This commit is contained in:
whitequark 2019-10-26 00:09:53 +00:00
parent 61e6267daf
commit 51269ad4a0
2 changed files with 21 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

15
nmigen/test/test_hdl_ast.py
View file

@ -533,15 +533,23 @@ class BitSelectTestCase(FHDLTestCase):
def test_shape(self):
s1 = self.c.bit_select(self.s, 2)
self.assertIsInstance(s1, Part)
self.assertEqual(s1.shape(), unsigned(2))
self.assertIsInstance(s1.shape(), Shape)
s2 = self.c.bit_select(self.s, 0)
self.assertIsInstance(s2, Part)
self.assertEqual(s2.shape(), unsigned(0))
def test_stride(self):
s1 = self.c.bit_select(self.s, 2)
self.assertIsInstance(s1, Part)
self.assertEqual(s1.stride, 1)
def test_const(self):
s1 = self.c.bit_select(1, 2)
self.assertIsInstance(s1, Slice)
self.assertRepr(s1, """(slice (const 8'd0) 1:3)""")
def test_width_wrong(self):
with self.assertRaises(TypeError):
self.c.bit_select(self.s, -1)
@ -558,13 +566,20 @@ class WordSelectTestCase(FHDLTestCase):
def test_shape(self):
s1 = self.c.word_select(self.s, 2)
self.assertIsInstance(s1, Part)
self.assertEqual(s1.shape(), unsigned(2))
self.assertIsInstance(s1.shape(), Shape)
def test_stride(self):
s1 = self.c.word_select(self.s, 2)
self.assertIsInstance(s1, Part)
self.assertEqual(s1.stride, 2)
def test_const(self):
s1 = self.c.word_select(1, 2)
self.assertIsInstance(s1, Slice)
self.assertRepr(s1, """(slice (const 8'd0) 2:4)""")
def test_width_wrong(self):
with self.assertRaises(TypeError):
self.c.word_select(self.s, 0)