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authorJohn David Anglin <dave.anglin@bell.net>2012-04-01 20:57:18 +0400
committerHelge Deller <deller@gmx.de>2013-01-08 02:06:22 +0400
commitcabd91c3bb74a5bc43c3192126af752891d11d77 (patch)
tree96be8d73cfe3a5228ecfee947d5dc6b2498503e8 /arch/parisc/math-emu
parentd287b8750e47c1702dab0e37ac11012bb751ece0 (diff)
downloadlinux-cabd91c3bb74a5bc43c3192126af752891d11d77.tar.xz
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 <dave.anglin@bell.net> Signed-off-by: Helge Deller <deller@gmx.de>
Diffstat (limited to 'arch/parisc/math-emu')
-rw-r--r--arch/parisc/math-emu/cnv_float.h11
1 files changed, 5 insertions, 6 deletions
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) \