[Bug 1232017] Re: [regression] mpfr tasinh test doesn't terminate when built with Linaro GCC 4.8 on armhf

[Kugan Vivekanandarajah]

Bad code is generated for mpfr_impl.h compare at line 1430. Due to this,
mpfr_asinh is producing wrong values for some inputs.

Original testcase involves random values so created a reduced case. With
the test case attached, even though _err1 is -38, "if condition" is
evaluated true. Following is the disassembly. Working is -O1
-fno-if-conversion. and Not working is -O1.

/* C Code */
    if (_err1 > 0)
      {

/* working code */
	cmp	r3, #0
	ble	.L6

/* not working code*/
	.loc 1 67 0
	movs	r3, r3, asl #1

The patch which is causing this regression seems to be
http://gcc.gnu.org/ml/gcc-patches/2013-02/msg00861.html

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https://bugs.launchpad.net/bugs/1232017

Title:
  [regression] mpfr tasinh test doesn't terminate when built with Linaro
  GCC 4.8 on armhf

Status in Linaro GCC:
  New
Status in “gcc-4.8” package in Ubuntu:
  Confirmed
Status in “gmp” package in Ubuntu:
  Confirmed
Status in “mpfr4” package in Ubuntu:
  Confirmed
Status in “gcc-4.8” source package in Saucy:
  Confirmed
Status in “gmp” source package in Saucy:
  Confirmed
Status in “mpfr4” source package in Saucy:
  Confirmed

Bug description:
  mpfr tasinh test doesn't terminate when built with Linaro GCC 4.8 on
  armhf. seen with -O1 and up. works with -O0

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