From 1272748886257ae4d73485eb7534756e89643091 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Wed, 10 Jan 2018 00:02:35 +0000 Subject: Fix ldbl-128ibm lrintl, lroundl missing "invalid" exceptions (bug 22690). The ldbl-128ibm implementations of lrintl and lroundl are missing "invalid" exceptions for certain overflow cases when compiled with GCC 8. The cause of this is after-the-fact integer overflow checks that fail when the compiler optimizes on the basis of integer overflow being undefined; GCC 8 must be able to detect new cases of undefinedness here. Failure: lrint (-0x80000001p0): Exception "Invalid operation" not set Failure: lrint_downward (-0x80000001p0): Exception "Invalid operation" not set Failure: lrint_towardzero (-0x80000001p0): Exception "Invalid operation" not set Failure: lrint_upward (-0x80000001p0): Exception "Invalid operation" not set Failure: lround (-0x80000001p0): Exception "Invalid operation" not set Failure: lround_downward (-0x80000001p0): Exception "Invalid operation" not set Failure: lround_towardzero (-0x80000001p0): Exception "Invalid operation" not set Failure: lround_upward (-0x80000001p0): Exception "Invalid operation" not set (Tested that these failures occur before the patch for powerpc soft-float, but the issue applies in principle for hard-float as well, whether or not the particular optimizations in fact occur there at present.) This patch fixes the bug by ensuring the additions / subtractions in question cast arguments to unsigned long int, or use 1UL as a constant argument, so that the arithmetic occurs in an unsigned type with the result then converted back to a signed type. Tested for powerpc (soft-float). [BZ #22690] * sysdeps/ieee754/ldbl-128ibm/s_lrintl.c (__lrintl): Use unsigned long int for arguments of possibly overflowing addition or subtraction. * sysdeps/ieee754/ldbl-128ibm/s_lroundl.c (__lroundl): Likewise. --- sysdeps/ieee754/ldbl-128ibm/s_lrintl.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'sysdeps/ieee754/ldbl-128ibm/s_lrintl.c') diff --git a/sysdeps/ieee754/ldbl-128ibm/s_lrintl.c b/sysdeps/ieee754/ldbl-128ibm/s_lrintl.c index 62180eb8cb..c2e2f68984 100644 --- a/sysdeps/ieee754/ldbl-128ibm/s_lrintl.c +++ b/sysdeps/ieee754/ldbl-128ibm/s_lrintl.c @@ -84,7 +84,7 @@ __lrintl (long double x) /* Peg at max/min values, assuming that the above conversions do so. Strictly speaking, we can return anything for values that overflow, but this is more useful. */ - res = hi + lo; + res = (long int) ((unsigned long int) hi + (unsigned long int) lo); /* This is just sign(hi) == sign(lo) && sign(res) != sign(hi). */ if (__glibc_unlikely (((~(hi ^ lo) & (res ^ hi)) < 0))) @@ -105,27 +105,27 @@ __lrintl (long double x) return res; if (xh < 0.0) - res -= 1; + res -= 1UL; else - res += 1; + res += 1UL; break; case FE_TOWARDZERO: if (res > 0 && (xh < 0.0 || (xh == 0.0 && xl < 0.0))) - res -= 1; + res -= 1UL; else if (res < 0 && (xh > 0.0 || (xh == 0.0 && xl > 0.0))) - res += 1; + res += 1UL; return res; break; case FE_UPWARD: if (xh > 0.0 || (xh == 0.0 && xl > 0.0)) - res += 1; + res += 1UL; break; case FE_DOWNWARD: if (xh < 0.0 || (xh == 0.0 && xl < 0.0)) - res -= 1; + res -= 1UL; break; } -- cgit 1.4.1