Différences

Ci-dessous, les différences entre deux révisions de la page.

--- prog:gcc [2020/02/25 00:11] – Ajout de la table virtuelle uniquement root
+++ prog:gcc [2024/11/12 12:48] (Version actuelle) – Déplacement des sanitizer vers une page dédiée root
@@ Ligne 1: / Ligne 1: @@
 Nightly pour [[https://bitbucket.org/ejsvifq_mabmip/mingw-gcc/src/master/|Windows 64]]
+[[https://gcc.gnu.org/projects/cxx-status.html|C++ status]], [[https://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html|libstdc++ status]]
+====Ubuntu====
+  * Installation en parallèle
+Ubuntu ne fournit pas de méthode 100% automatique. Il faut passer manuellement par ''update-alternatives''.
+<code bash>
+sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-11 110 --slave /usr/bin/g++ g++ /usr/bin/g++-11
+</code>
+Utiliser pour switcher entre les versions :
+<code bash>
+sudo update-alternatives --config gcc
+</code>
 =====Diagnostic=====
@@ Ligne 52: / Ligne 70: @@
 </code>
-  * clang : ''clang -cc1 -emit-llvm -fdump-record-layouts-simple main.cc''
+  * clang : ''clang -cc1 -emit-llvm -fdump-record-layouts main.cc''
+Ci-dessous, on affiche que le contenu des ''Dumping AST Record Layout''.
 <code>
-; ModuleID = 'main.cc'
+*** Dumping AST Record Layout
-source_filename = "main.cc"
+| class VirtualBase
-target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+|   (VirtualBase vtable pointer)
-target triple = "x86_64-pc-linux-gnu"
+           | [sizeof=8, dsize=8, align=8,
+           |  nvsize=8, nvalign=8]
-%class.VirtualDerived = type <{ %class.VirtualBase, i32, [4 x i8] }>
+*** Dumping AST Record Layout
-%class.VirtualBase = type { i32 (...)** }
+ | class VirtualDerived
+ |   class VirtualBase (primary base)
-$_ZN14VirtualDerivedC1Ev = comdat any
+ |     (VirtualBase vtable pointer)
+ |   int m_counter
-$_ZN14VirtualDerivedC2Ev = comdat any
+           | [sizeof=16, dsize=12, align=8,
+           |  nvsize=12, nvalign=8]
-$_ZN11VirtualBaseC2Ev = comdat any
-$_ZN14VirtualDerived4tickEi = comdat any
-$_ZTV14VirtualDerived = comdat any
-$_ZTS14VirtualDerived = comdat any
-$_ZTS11VirtualBase = comdat any
-$_ZTI11VirtualBase = comdat any
-$_ZTI14VirtualDerived = comdat any
-$_ZTV11VirtualBase = comdat any
-@_ZTV14VirtualDerived = linkonce_odr unnamed_addr constant { [3 x i8*] } { [3 x i8*] [i8* null, i8* bitcast ({ i8*, i8*, i8* }* @_ZTI14VirtualDerived to i8*), i8* bitcast (i32 (%class.VirtualDerived*, i32)* @_ZN14VirtualDerived4tickEi to i8*)] }, comdat, align 8
-@_ZTVN10__cxxabiv120__si_class_type_infoE = external global i8*
-@_ZTS14VirtualDerived = linkonce_odr constant [17 x i8] c"14VirtualDerived\00", comdat, align 1
-@_ZTVN10__cxxabiv117__class_type_infoE = external global i8*
-@_ZTS11VirtualBase = linkonce_odr constant [14 x i8] c"11VirtualBase\00", comdat, align 1
-@_ZTI11VirtualBase = linkonce_odr constant { i8*, i8* } { i8* bitcast (i8** getelementptr inbounds (i8*, i8** @_ZTVN10__cxxabiv117__class_type_infoE, i64 2) to i8*), i8* getelementptr inbounds ([14 x i8], [14 x i8]* @_ZTS11VirtualBase, i32 0, i32 0) }, comdat, align 8
-@_ZTI14VirtualDerived = linkonce_odr constant { i8*, i8*, i8* } { i8* bitcast (i8** getelementptr inbounds (i8*, i8** @_ZTVN10__cxxabiv120__si_class_type_infoE, i64 2) to i8*), i8* getelementptr inbounds ([17 x i8], [17 x i8]* @_ZTS14VirtualDerived, i32 0, i32 0), i8* bitcast ({ i8*, i8* }* @_ZTI11VirtualBase to i8*) }, comdat, align 8
-@_ZTV11VirtualBase = linkonce_odr unnamed_addr constant { [3 x i8*] } { [3 x i8*] [i8* null, i8* bitcast ({ i8*, i8* }* @_ZTI11VirtualBase to i8*), i8* bitcast (void ()* @__cxa_pure_virtual to i8*)] }, comdat, align 8
-; Function Attrs: noinline nounwind optnone
-define void @_Z1fv() #0 {
-entry:
-  %v = alloca %class.VirtualDerived, align 8
-  call void @_ZN14VirtualDerivedC1Ev(%class.VirtualDerived* %v)
-  ret void
-}
-; Function Attrs: noinline nounwind optnone
-define linkonce_odr void @_ZN14VirtualDerivedC1Ev(%class.VirtualDerived* %this) unnamed_addr #0 comdat align 2 {
-entry:
-  %this.addr = alloca %class.VirtualDerived*, align 8
-  store %class.VirtualDerived* %this, %class.VirtualDerived** %this.addr, align 8
-  %this1 = load %class.VirtualDerived*, %class.VirtualDerived** %this.addr, align 8
-  call void @_ZN14VirtualDerivedC2Ev(%class.VirtualDerived* %this1)
-  ret void
-}
-; Function Attrs: noinline nounwind optnone
-define linkonce_odr void @_ZN14VirtualDerivedC2Ev(%class.VirtualDerived* %this) unnamed_addr #0 comdat align 2 {
-entry:
-  %this.addr = alloca %class.VirtualDerived*, align 8
-  store %class.VirtualDerived* %this, %class.VirtualDerived** %this.addr, align 8
-  %this1 = load %class.VirtualDerived*, %class.VirtualDerived** %this.addr, align 8
-  %0 = bitcast %class.VirtualDerived* %this1 to %class.VirtualBase*
-  call void @_ZN11VirtualBaseC2Ev(%class.VirtualBase* %0) #1
-  %1 = bitcast %class.VirtualDerived* %this1 to i32 (...)***
-  store i32 (...)** bitcast (i8** getelementptr inbounds ({ [3 x i8*] }, { [3 x i8*] }* @_ZTV14VirtualDerived, i32 0, inrange i32 0, i32 2) to i32 (...)**), i32 (...)*** %1, align 8
-  %m_counter = getelementptr inbounds %class.VirtualDerived, %class.VirtualDerived* %this1, i32 0, i32 1
-  store i32 0, i32* %m_counter, align 8
-  ret void
-}
-; Function Attrs: noinline nounwind optnone
-define linkonce_odr void @_ZN11VirtualBaseC2Ev(%class.VirtualBase* %this) unnamed_addr #0 comdat align 2 {
-entry:
-  %this.addr = alloca %class.VirtualBase*, align 8
-  store %class.VirtualBase* %this, %class.VirtualBase** %this.addr, align 8
-  %this1 = load %class.VirtualBase*, %class.VirtualBase** %this.addr, align 8
-  %0 = bitcast %class.VirtualBase* %this1 to i32 (...)***
-  store i32 (...)** bitcast (i8** getelementptr inbounds ({ [3 x i8*] }, { [3 x i8*] }* @_ZTV11VirtualBase, i32 0, inrange i32 0, i32 2) to i32 (...)**), i32 (...)*** %0, align 8
-  ret void
-}
-; Function Attrs: noinline nounwind optnone
-define linkonce_odr i32 @_ZN14VirtualDerived4tickEi(%class.VirtualDerived* %this, i32 %n) unnamed_addr #0 comdat align 2 {
-entry:
-  %this.addr = alloca %class.VirtualDerived*, align 8
-  %n.addr = alloca i32, align 4
-  store %class.VirtualDerived* %this, %class.VirtualDerived** %this.addr, align 8
-  store i32 %n, i32* %n.addr, align 4
-  %this1 = load %class.VirtualDerived*, %class.VirtualDerived** %this.addr, align 8
-  %0 = load i32, i32* %n.addr, align 4
-  %m_counter = getelementptr inbounds %class.VirtualDerived, %class.VirtualDerived* %this1, i32 0, i32 1
-  %1 = load i32, i32* %m_counter, align 8
-  %add = add nsw i32 %1, %0
-  store i32 %add, i32* %m_counter, align 8
-  %m_counter2 = getelementptr inbounds %class.VirtualDerived, %class.VirtualDerived* %this1, i32 0, i32 1
-  %2 = load i32, i32* %m_counter2, align 8
-  ret i32 %2
-}
-declare void @__cxa_pure_virtual() unnamed_addr
-attributes #0 = { noinline nounwind optnone "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-features"="+cx8,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
-attributes #1 = { nounwind }
-!llvm.module.flags = !{!0}
-!llvm.ident = !{!1}
-!0 = !{i32 1, !"wchar_size", i32 4}
-!1 = !{!"clang version 11.0.0 "}
 </code>
@@ Ligne 192: / Ligne 116: @@
 [[https://www.thegeekstuff.com/2012/08/gprof-tutorial/|GPROF Tutorial – How to use Linux GNU GCC Profiling Tool]] {{ :prog:gcc:gprof_tutorial_how_to_use_linux_gnu_gcc_profiling_tool_2020-02-24_3_24_57_pm_.html |Archive du 20/08/2012 le 24/02/2020}}
-=====Commun avec clang=====
-====Sanitizer====
-Il existe ''-fsanitize=address,thread,undefined'' mais ''address'' et ''thread'' ne sont pas compatible simultanément.
-===address===
-Il détecte des erreurs de type global-buffer-overflow, heap-use-after-free.
-[[https://www.youtube.com/watch?v=qTkYDA0En6U|CppCon 2015: Kostya Serebryany “Beyond Sanitizers, Fuzzing and Hardening your C++ apps for Security and Reliability”]]
-  * global-buffer-overflow
+====Couverture de code====
-<file c main.c>
-int global_array[100] = {-1};
-int main(int argc, char **argv) {
+Options à ajouter à la compilation : ''-O0 %%--%%coverage''
-  return global_array[argc+100];
-}
-</file>
-  gcc main.c -g -fsanitize=address -o main && ./main
+Options à ajouter au lieur : ''%%--%%coverage''
-  =================================================================
+Puis exécuter le ou les programmes. Attention, pas d'exécution en parallèle. Les fichiers ''.gcno'' ne le supportent pas.
-  ==2500==ERROR: AddressSanitizer: global-buffer-overflow on address 0x000000740cf4 at pc 0x00000050d9bf bp 0x7ffeabb89b70 sp 0x7ffeabb89b68
-  READ of size 4 at 0x000000740cf4 thread T0
-      #0 0x50d9be in main /tmp/main.c:4:10
-      #1 0x7f1208faa461 in __libc_start_main /home/legarrec/info/portage/sys-libs/glibc-2.25-r9/work/glibc-2.25/csu/../csu/libc-start.c:295
-      #2 0x419709 in _start (/tmp/main+0x419709)
-x000000740cf4 is located 4 bytes to the right of global variable 'global_array' defined in 'main.c:1:5' (0x740b60) of size 400
-  SUMMARY: AddressSanitizer: global-buffer-overflow /tmp/main.c:4:10 in main
-  Shadow bytes around the buggy address:
-x0000800e0140: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0000800e0150: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0000800e0160: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0000800e0170: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0000800e0180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-  =>0x0000800e0190: 00 00 00 00 00 00 00 00 00 00 00 00 00 00[f9]f9
-x0000800e01a0: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 00 00 00 00
-x0000800e01b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0000800e01c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0000800e01d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0000800e01e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-  Shadow byte legend (one shadow byte represents 8 application bytes):
-    Addressable:           00
-    Partially addressable: 01 02 03 04 05 06 07
-    Heap left redzone:       fa
-    Freed heap region:       fd
-    Stack left redzone:      f1
-    Stack mid redzone:       f2
-    Stack right redzone:     f3
-    Stack after return:      f5
-    Stack use after scope:   f8
-    Global redzone:          f9
-    Global init order:       f6
-    Poisoned by user:        f7
-    Container overflow:      fc
-    Array cookie:            ac
-    Intra object redzone:    bb
-    ASan internal:           fe
-    Left alloca redzone:     ca
-    Right alloca redzone:    cb
-  ==2500==ABORTING
-[[prog:valgrind|valgrind]] ne détecte pas l'erreur.
+<code bash>
+lcov --capture --directory build --gcov-tool /usr/bin/gcov-10 --rc lcov_branch_coverage=1 --output-file build/coverage.info
-  * heap-use-after-free
+lcov --remove build/coverage.info "/usr/include/*" --rc lcov_branch_coverage=1 -o build/coverage2.info
-<file c main2.cc>
+genhtml --output-directory build/coverage --demangle-cpp --num-spaces 2 --sort --function-coverage --branch-coverage --legend build/coverage2.info
-int main(int argc, char **argv) {
+find build/coverage -name "*.html" -exec sed -i -r "s#headerValue""\>.*-.*-.* .*:.*:.*td#headerValue""></td#g" {} \;
-  int *array = new int[100];
+</code>
-  delete [] array;
-  return array[argc];
-}
-</file>
-  g++ main2.c -g -fsanitize=address -o main2 && ./main2
-  =================================================================
-  ==2765==ERROR: AddressSanitizer: heap-use-after-free on address 0x614000000044 at pc 0x000000512445 bp 0x7ffd51684f60 sp 0x7ffd51684f58
-  READ of size 4 at 0x614000000044 thread T0
-      #0 0x512444 in main /tmp/main2.c:4:10
-      #1 0x7fd8d0086461 in __libc_start_main /home/legarrec/info/portage/sys-libs/glibc-2.25-r9/work/glibc-2.25/csu/../csu/libc-start.c:295
-      #2 0x419d29 in _start (/tmp/main2+0x419d29)
-x614000000044 is located 4 bytes inside of 400-byte region [0x614000000040,0x6140000001d0)
-  freed by thread T0 here:
-      #0 0x50ef30 in operator delete[](void*) /home/legarrec/info/portage/sys-libs/compiler-rt-sanitizers-5.0.0/work/compiler-rt-5.0.0.src/lib/asan/asan_new_delete.cc:141
-      #1 0x5123f6 in main /tmp/main2.c:3:3
-      #2 0x7fd8d0086461 in __libc_start_main /home/legarrec/info/portage/sys-libs/glibc-2.25-r9/work/glibc-2.25/csu/../csu/libc-start.c:295
-      #3 0x419d29 in _start (/tmp/main2+0x419d29)
-  previously allocated by thread T0 here:
-      #0 0x50e1c8 in operator new[](unsigned long) /home/legarrec/info/portage/sys-libs/compiler-rt-  sanitizers-5.0.0/work/compiler-rt-5.0.0.src/lib/asan/asan_new_delete.cc:95
-      #1 0x5123d4 in main /tmp/main2.c:2:16
-      #2 0x7fd8d0086461 in __libc_start_main /home/legarrec/info/portage/sys-libs/glibc-2.25-r9/work/glibc-2.25/csu/../csu/libc-start.c:295
-      #3 0x419d29 in _start (/tmp/main2+0x419d29)
-  SUMMARY: AddressSanitizer: heap-use-after-free /tmp/main2.c:4:10 in main
-  Shadow bytes around the buggy address:
-x0c287fff7fb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0c287fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0c287fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0c287fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0c287fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-  =>0x0c287fff8000: fa fa fa fa fa fa fa fa[fd]fd fd fd fd fd fd fd
-x0c287fff8010: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
-x0c287fff8020: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
-x0c287fff8030: fd fd fd fd fd fd fd fd fd fd fa fa fa fa fa fa
-x0c287fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
-x0c287fff8050: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
-[[prog:valgrind|valgrind]] détecte l'erreur.
-  ==2787== Command: ./main2
-  ==2787==
-  ==2787== Invalid read of size 4
-  ==2787==    at 0x4005AF: main (main2.c:4)
-  ==2787==  Address 0x5b25c84 is 4 bytes inside a block of size 400 free'd
-  ==2787==    at 0x4C2CAA5: operator delete[](void*) (vg_replace_malloc.c:621)
-  ==2787==    by 0x4005A6: main (main2.c:3)
-  ==2787==  Block was alloc'd at
-  ==2787==    at 0x4C2BAC8: operator new[](unsigned long) (vg_replace_malloc.c:423)
-  ==2787==    by 0x400584: main (main2.c:2)
-  * stack-use-after-return
-<file c main3.c>
-int *g;
-void LeakLocal() {
-  int local;
-  g = &local;
-}
-int main(){
-  LeakLocal();
-  return *g;
-}
-</file>
-  gcc main3.c -g -o main3 -fsanitize=address
-  ASAN_OPTIONS=detect_stack_use_after_return=1 ./main3
-L'utilisation de ''ASAN_OPTIONS=detect_stack_use_after_return=1'' est nécessaire car cette option peut créer des faux positifs.
-  =================================================================
-  ==2907==ERROR: AddressSanitizer: stack-use-after-return on address 0x7f57b2a00020 at pc 0x00000050db25 bp 0x7ffe8dfc7330 sp 0x7ffe8dfc7328
-  READ of size 4 at 0x7f57b2a00020 thread T0
-      #0 0x50db24 in main /tmp/main3.c:10:10
-      #1 0x7f57b604d461 in __libc_start_main /home/legarrec/info/portage/sys-libs/glibc-2.25-r9/work/glibc-2.25/csu/../csu/libc-start.c:295
-      #2 0x419709 in _start (/tmp/main3+0x419709)
-  Address 0x7f57b2a00020 is located in stack of thread T0 at offset 32 in frame
-      #0 0x50d95f in LeakLocal /tmp/main3.c:3
-    This frame has 1 object(s):
-      [32, 36) 'local' (line 4) <== Memory access at offset 32 is inside this variable
-  HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext
-        (longjmp and C++ exceptions *are* supported)
-  SUMMARY: AddressSanitizer: stack-use-after-return /tmp/main3.c:10:10 in main
-  Shadow bytes around the buggy address:
-x0feb76537fb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0feb76537fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0feb76537fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0feb76537fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0feb76537ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-  =>0x0feb76538000: f5 f5 f5 f5[f5]f5 f5 f5 00 00 00 00 00 00 00 00
-x0feb76538010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0feb76538020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0feb76538030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0feb76538040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-x0feb76538050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
-[[prog:valgrind|valgrind]] détecte l'erreur.
-  valgrind --track-origins=yes ./main3
-  ==2961== Syscall param exit_group(status) contains uninitialised byte(s)
-  ==2961==    at 0x4F002B8: _Exit (_exit.c:31)
-  ==2961==    by 0x4E70423: __run_exit_handlers (exit.c:98)
-  ==2961==    by 0x4E704DC: exit (exit.c:105)
-  ==2961==    by 0x4E58468: (below main) (libc-start.c:329)
-  ==2961==  Uninitialised value was created by a stack allocation
-  ==2961==    at 0x4004A4: main (main3.c:10)
-===thread===
-<file cpp main4.cc>
-#include <thread>
-int main() {
-  int x;
-  std::thread t([&]{x=42;});
-  x = 43;
-  t.join();
-  return 0;
-}
-</file>
-  g++ -std=c++11 main4.c -g -o main4 -fsanitize=thread
-<note important>Le plantage reste aléatoire et il est nécessaire de lancer l'application plusieurs fois.
-</note>
-  ==================
-  WARNING: ThreadSanitizer: data race (pid=3226)
-    Write of size 4 at 0x7ffd04d5b144 by thread T1:
-      #0 operator() /tmp/main4.c:5 (main4+0x000000400d0b)
-      #1 __invoke_impl<void, main()::<lambda()> > /usr/lib/gcc/x86_64-pc-linux-gnu/7.2.0/include/g++-v7/bits/invoke.h:60 (main4+0x000000401171)
-      #2 __invoke<main()::<lambda()> > /usr/lib/gcc/x86_64-pc-linux-gnu/7.2.0/include/g++-v7/bits/invoke.h:95 (main4+0x000000400e30)
-      #3 _M_invoke<0> /usr/lib/gcc/x86_64-pc-linux-gnu/7.2.0/include/g++-v7/thread:234 (main4+0x0000004014b5)
-      #4 operator() /usr/lib/gcc/x86_64-pc-linux-gnu/7.2.0/include/g++-v7/thread:243 (main4+0x000000401448)
-      #5 _M_run /usr/lib/gcc/x86_64-pc-linux-gnu/7.2.0/include/g++-v7/thread:186 (main4+0x0000004013ee)
-      #6 <null> <null> (libstdc++.so.6+0x0000000e251e)
-    Previous write of size 4 at 0x7ffd04d5b144 by main thread:
-      #0 main /tmp/main4.c:6 (main4+0x000000400d75)
-    Location is stack of main thread.
-    Thread T1 (tid=3228, running) created by main thread at:
-      #0 pthread_create <null> (libtsan.so.0+0x00000002917a)
-      #1 std::thread::_M_start_thread(std::unique_ptr<std::thread::_State, std::default_delete<std::thread::_State> >, void (*)()) <null> (libstdc++.so.6+0x0000000e288c)
-      #2 main /tmp/main4.c:5 (main4+0x000000400d69)
-  SUMMARY: ThreadSanitizer: data race /tmp/main4.c:5 in operator()
-  ==================
-  ThreadSanitizer: reported 1 warnings
-[[prog:valgrind|valgrind]] ne détecte pas l'erreur.
-===undefined===
-<file c main5.c>
-int main(int argc, char **argv) {
-  int t = argc << 16;
-  return t*t;
-}
-</file>
-  gcc -fsanitize=undefined main5.c -g -o main5
-  main6.c:3:11: runtime error: signed integer overflow: 65536 * 65536 cannot be represented in type 'int'
+Attention, la version de gcov doit correspondre à celle de gcc.
-[[prog:valgrind|valgrind]] ne détecte pas l'erreur.
+En option, on supprime la date pour qu'un diff simple puisse se faire.