FastFPE's implementation of the 'cmf' and 'cnf' opcodes incorrectly treat +0 and -0 as inequal numbers, which violates IEEE 754.
The enclosed patch fixes this bug by testing for the magic exponent that indicates 'zero' before testing the signs of the comparison operands. Minimal test cases that illustrate the problem are at <http://www.booyaka.com/~paul/arm/fpa11_cmf_tests.tar.gz>. After patching with the patch below, the result of the test cases is identical between NWFPE and FastFPE. (The test cases are derived from code posted earlier by Nicholas Clark <[EMAIL PROTECTED]> - thanks!) This patch applies cleanly against 2.4.19-rmk2 and 2.5.30-rmk1. (This is also true for the previous 'lfm' patch.) Thanks again to Tony Lindgren <[EMAIL PROTECTED]> for his help with catching this bug. - Paul --- linux-2.4.19-rmk2/arch/arm/fastfpe/CPRT.S Wed Sep 25 01:38:54 2002 +++ linux-2.4.19-rmk2-pjw/arch/arm/fastfpe/CPRT.S.new Wed Sep 25 01:36:08 2002 @@ -128,6 +128,10 @@ cmp r8,#0x7fffffff cmpeq r4,#0xffffffff beq CPRT_cmf_unordered + + cmp r7,#0x80000000 @ zero can be either positive or negative, + cmpeq r8,#0x80000000 @ but +0 is equal to -0 in IEEE 754 + beq CPRT_cmf_equal cmp r1,r2 beq CPRT_cmf_equalsign
