From: drh <>
Date: Wed, 14 Jun 2023 12:19:07 +0000 (+0000)
Subject: Work around what appears to be a GCC 32-bit optimization problem in the
X-Git-Tag: version-3.43.0~198
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0c04f2e57676322b989dc9e91ddc0af250294b55;p=thirdparty%2Fsqlite.git

Work around what appears to be a GCC 32-bit optimization problem in the
computeHMS() routine of the date/time logic.

FossilOrigin-Name: aebdbcbebff1319dd00551c9fb9ad4b08859f10e87f097295d564ae1ba188c02
---

diff --git a/manifest b/manifest
index 91e016c410..4f4560a756 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Improved\ssqlite3_error_offset()\svalues\sfor\sbare\scolumn\serrors\son\s'*'\sand\n'table.*'\sexpressions\sin\sSELECT\sstatements.
-D 2023-06-13T18:10:52.281
+C Work\saround\swhat\sappears\sto\sbe\sa\sGCC\s32-bit\soptimization\sproblem\sin\sthe\ncomputeHMS()\sroutine\sof\sthe\sdate/time\slogic.
+D 2023-06-14T12:19:07.968
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -582,7 +582,7 @@ F src/build.c cb54df6fd018a18e940a251c5e31780ffba8bc6c7a01e670b96a489adcbfb3b4
 F src/callback.c db3a45e376deff6a16c0058163fe0ae2b73a2945f3f408ca32cf74960b28d490
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
 F src/ctime.c 20507cc0b0a6c19cd882fcd0eaeda32ae6a4229fb4b024cfdf3183043d9b703d
-F src/date.c 17e090a9cd6355b625a0a242f2ce4b2898171c6c5ff725863ca4ce73f1e99bb1
+F src/date.c a93926302c5b2c7c115e91318f7cc48b0cb532d0f8159db352f40142b897acee
 F src/dbpage.c f3eea5f7ec47e09ee7da40f42b25092ecbe961fc59566b8e5f705f34335b2387
 F src/dbstat.c ec92074baa61d883de58c945162d9e666c13cd7cf3a23bc38b4d1c4d0b2c2bef
 F src/delete.c 1b00589aa4f2c50beba39f9da5166fc2161234580ea8c0d087b6d5c2c7a17c21
@@ -2040,10 +2040,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P d57ddbf4eeeb3ccfe31871f098045b9e58634153a3c3030f597cb58c1177218a
-Q +446ad162f76f2a32f3bfc5b5c1dadc8a139d4f338abb91fd912141ed8a768e8e
-Q +c29ec76944e2ee62e3f3383047a92c05e97f59387874985381e74a47ffe69d28
-R b4b614052d980dd3672d7fe75c7343e5
+P 118fe600876686273f85d0a080a21267e83c11826365f3220336b1bd39562518
+R 636b0de7e817acb69f938b4ec83d6997
 U drh
-Z 63bbd4bc20e73a56a27bb600d55e31ce
+Z 5b8bcd505fc6af17eee1501e48c257a1
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index aa575a5229..6218540ec2 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-118fe600876686273f85d0a080a21267e83c11826365f3220336b1bd39562518
\ No newline at end of file
+aebdbcbebff1319dd00551c9fb9ad4b08859f10e87f097295d564ae1ba188c02
\ No newline at end of file
diff --git a/src/date.c b/src/date.c
index b7391c2c03..6d46e59660 100644
--- a/src/date.c
+++ b/src/date.c
@@ -448,6 +448,32 @@ static void computeYMD(DateTime *p){
   p->validYMD = 1;
 }
 
+/* GCC (and sometimes Clang too) will sometimes be off by 1 millisecond
+** in computeHMS() on 32-bit platforms with optimization enabled.
+** I don't know if this is a compiler bug or a bug in the code.  It is hard
+** to debug because with optimization enabled, gdb skips around so much
+** you cannot see what is happening, and if you try adding debug printf()s
+** to the code, the problem goes away.
+**
+** For now, I will work around the problem by disabling optimizations in
+** the computeHMS() routine.
+**
+** Problem seen using gcc-5.4.0, gcc-9.4.0, clang-10.  Works ok on
+** MSVC, clang-3.4, and clang-6.0.
+**
+** Whatever the problem is, it causes some answers to be off by one
+** millisecond.  So we get results like "2021-03-05 03:04:05.599" instead
+** of the desired result of "2021-03-05 03:04:05.600".
+**
+** To reproduce the problem using TH3:
+**
+**    ./th3make debug.rc -O1 -m32 cfg/c1.cfg cov1/date8.test
+*/
+#if SQLITE_PTRSIZE==4 && GCC_VERSION>0
+#pragma GCC push_options
+#pragma GCC optimize ("O0")
+#endif
+
 /*
 ** Compute the Hour, Minute, and Seconds from the julian day number.
 */
@@ -467,6 +493,11 @@ static void computeHMS(DateTime *p){
   p->validHMS = 1;
 }
 
+/* Reactivate GCC optimization */
+#if SQLITE_PTRSIZE==4 && GCC_VERSION>0
+#pragma GCC pop_options
+#endif
+
 /*
 ** Compute both YMD and HMS
 */