From patchwork Wed Jan 10 00:03:22 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joseph Myers X-Patchwork-Id: 25302 Received: (qmail 49764 invoked by alias); 10 Jan 2018 00:03:31 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 49737 invoked by uid 89); 10 Jan 2018 00:03:30 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-24.5 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, RCVD_IN_DNSWL_NONE, SPF_PASS, URIBL_RED autolearn=ham version=3.3.2 spammy= X-HELO: relay1.mentorg.com Date: Wed, 10 Jan 2018 00:03:22 +0000 From: Joseph Myers To: Subject: Fix ldbl-128ibm lrintl, lroundl missing "invalid" exceptions (bug 22690) [committed] Message-ID: User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 X-ClientProxiedBy: svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) To svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) 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). Committed. 2018-01-10 Joseph Myers [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. diff --git a/sysdeps/ieee754/ldbl-128ibm/s_lrintl.c b/sysdeps/ieee754/ldbl-128ibm/s_lrintl.c index 62180eb..c2e2f68 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; } diff --git a/sysdeps/ieee754/ldbl-128ibm/s_lroundl.c b/sysdeps/ieee754/ldbl-128ibm/s_lroundl.c index 9cf4a12..010e8e2 100644 --- a/sysdeps/ieee754/ldbl-128ibm/s_lroundl.c +++ b/sysdeps/ieee754/ldbl-128ibm/s_lroundl.c @@ -80,7 +80,7 @@ __lroundl (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))) @@ -92,21 +92,21 @@ __lroundl (long double x) hi = res; if (xh > 0.5) { - res += 1; + res += 1UL; } else if (xh == 0.5) { if (xl > 0.0 || (xl == 0.0 && res >= 0)) - res += 1; + res += 1UL; } else if (-xh > 0.5) { - res -= 1; + res -= 1UL; } else if (-xh == 0.5) { if (xl < 0.0 || (xl == 0.0 && res <= 0)) - res -= 1; + res -= 1UL; } if (__glibc_unlikely (((~(hi ^ (res - hi)) & (res ^ hi)) < 0)))