From: John David Anglin Date: Sun, 1 Apr 2012 16:57:18 +0000 (-0400) Subject: parisc: avoid undefined shift in cnv_float.h X-Git-Tag: v3.8-rc5~21^2~3 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=cabd91c3bb74a5bc43c3192126af752891d11d77;p=karo-tx-linux.git parisc: avoid undefined shift in cnv_float.h The attached change fixes a float conversion problem found running the GCC testsuite with GCC configured with --with-arch=2.0. The actual problem occurs for an exponent value of 63. This is the maximum exponent value that can be passed. This causes a left shift by 32 in the else hunk of the macro. This causes undefined behavior and the wrong value is returned for dresultB. The fix is the check "exponent <= 62". If the exponent is 63, dresultB is set to 0. The patch also optimizes the operation a bit by copying "Sall(sgl_value) << SGL_EXP_LENGTH" to val, so that sgl_value is not modified. Signed-off-by: John David Anglin Signed-off-by: Helge Deller --- diff --git a/arch/parisc/math-emu/cnv_float.h b/arch/parisc/math-emu/cnv_float.h index 9071e093164a..933423fa5144 100644 --- a/arch/parisc/math-emu/cnv_float.h +++ b/arch/parisc/math-emu/cnv_float.h @@ -347,16 +347,15 @@ Sgl_isinexact_to_fix(sgl_value,exponent) #define Duint_from_sgl_mantissa(sgl_value,exponent,dresultA,dresultB) \ - {Sall(sgl_value) <<= SGL_EXP_LENGTH; /* left-justify */ \ + {unsigned int val = Sall(sgl_value) << SGL_EXP_LENGTH; \ if (exponent <= 31) { \ - Dintp1(dresultA) = 0; \ - Dintp2(dresultB) = (unsigned)Sall(sgl_value) >> (31 - exponent); \ + Dintp1(dresultA) = 0; \ + Dintp2(dresultB) = val >> (31 - exponent); \ } \ else { \ - Dintp1(dresultA) = Sall(sgl_value) >> (63 - exponent); \ - Dintp2(dresultB) = Sall(sgl_value) << (exponent - 31); \ + Dintp1(dresultA) = val >> (63 - exponent); \ + Dintp2(dresultB) = exponent <= 62 ? val << (exponent - 31) : 0; \ } \ - Sall(sgl_value) >>= SGL_EXP_LENGTH; /* return to original */ \ } #define Duint_setzero(dresultA,dresultB) \