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[Bug target/81879] Bad compilation of small program if LTO is used
- From: "freddy77 at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 17 Aug 2017 11:49:08 +0000
- Subject: [Bug target/81879] Bad compilation of small program if LTO is used
- Auto-submitted: auto-generated
- References: <bug-81879-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81879
--- Comment #1 from Frediano Ziglio <freddy77 at gmail dot com> ---
This is weird. If after the
x86_64-w64-mingw32-g++ -flto -O2 -g -save-temps -Wall -Werror -Wextra
-static -mconsole -o test.exe test.cpp
command I run
x86_64-w64-mingw32-g++ -v test.exe.ltrans0.s -static -o test.exe -mconsole
the executable I get is able to run.
Trying to find some difference between the executables I found that the widen
call is different, specifically in one case (the one crashing) do_widen is not
generated. Quite weird that in the wrong code %rdx is assigned to a pointer
inside a function while in the working case a valid pointer to a function is
used.
@@ -49312,7 +49312,7 @@
---: 89 d6 mov %edx,%esi
---: e8 c0 fa ff ff callq 4275e0
<std::ctype<char>::_M_widen_init() const>
---: 48 8b 03 mov (%rbx),%rax
----: 48 8d 15 46 00 00 00 lea 0x46(%rip),%rdx # 427b70
<std::ctype<char>::do_widen(char) const>
+---: 48 8d 15 00 00 00 00 lea 0x0(%rip),%rdx # 427b2a
<std::ctype<char>::widen(char) const [clone .part.23]+0x1a>
---: 48 8b 40 30 mov 0x30(%rax),%rax
---: 48 39 d0 cmp %rdx,%rax
---: 75 0d jne 427b40 <std::ctype<char>::widen(char)
const [clone .part.23]+0x30>
@@ -49345,30 +49345,13 @@
---: 90 nop
---: 90 nop
-0000000000427b70 <std::ctype<char>::do_widen(char) const>:
----: 89 d0 mov %edx,%eax
----: c3 retq
----: 90 nop
----: 90 nop
----: 90 nop
----: 90 nop
----: 90 nop
----: 90 nop
----: 90 nop
----: 90 nop
----: 90 nop
----: 90 nop
----: 90 nop
----: 90 nop
----: 90 nop