[pypy-commit] pypy faster-rstruct-2: we cannot use the fastpath for '<f' or '>f', because we need to check for overflow in that case. It is fine to use the fastpath for doubles though, because there is no risk of overflow

[antocuni]

Author: Antonio Cuni <anto.cuni at gmail.com>
Branch: faster-rstruct-2
Changeset: r91286:6c228d591ce8
Date: 2017-05-15 00:06 +0200
http://bitbucket.org/pypy/pypy/changeset/6c228d591ce8/

Log:	we cannot use the fastpath for '<f' or '>f', because we need to
	check for overflow in that case. It is fine to use the fastpath for
	doubles though, because there is no risk of overflow

diff --git a/rpython/rlib/rstruct/standardfmttable.py b/rpython/rlib/rstruct/standardfmttable.py
--- a/rpython/rlib/rstruct/standardfmttable.py
+++ b/rpython/rlib/rstruct/standardfmttable.py
@@ -106,7 +106,7 @@
     size = rffi.sizeof(TYPE)
     def packer(fmtiter):
         fl = fmtiter.accept_float_arg()
-        if pack_fastpath(TYPE)(fmtiter, fl):
+        if TYPE is not rffi.FLOAT and pack_fastpath(TYPE)(fmtiter, fl):
             return
         # slow path
         try:
diff --git a/rpython/rlib/rstruct/test/test_pack.py b/rpython/rlib/rstruct/test/test_pack.py
--- a/rpython/rlib/rstruct/test/test_pack.py
+++ b/rpython/rlib/rstruct/test/test_pack.py
@@ -1,6 +1,7 @@
 import pytest
 from rpython.rlib.rarithmetic import r_ulonglong
 from rpython.rlib.rstruct import standardfmttable, nativefmttable
+from rpython.rlib.rstruct.error import StructOverflowError
 from rpython.rlib.mutbuffer import MutableStringBuffer
 import struct
 
@@ -93,6 +94,14 @@
         self.check('f', 123.456)
         self.check('d', 123.456789)
 
+    def test_float_overflow(self):
+        if self.fmt_prefix == '@':
+            # native packing, no overflow
+            self.check('f', 10e100)
+        else:
+            # non-native packing, should raise
+            pytest.raises(StructOverflowError, "self.mypack('f', 10e100)")
+
     def test_pack_char(self):
         self.check('c', 'a')