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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/109299] [12/13 Regression] wrong warning on
 std::wstring with -O2 -std=c++20 -D_FORTIFY_SOURCE=2
Date: Tue, 28 Mar 2023 10:03:59 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 12.2.0
X-Bugzilla-Keywords: diagnostic
X-Bugzilla-Severity: normal
X-Bugzilla-Who: redi at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P2
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 12.3
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Message-ID: <bug-109299-4-A2nzltR9RT@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-109299-4@http.gcc.gnu.org/bugzilla/>
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109299

--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Yes, it looks better:

--- 109299-orig.s       2023-03-28 11:01:09.886119878 +0100
+++ 109299-fixed.s      2023-03-28 11:01:21.361187289 +0100
@@ -235,21 +235,14 @@
        xorl    %esi, %esi
        call    wmemset
        movq    (%rsp), %rax
-       leaq    48(%rsp), %rdi
-       movq    $42, 8(%rsp)
-       movq    %rdi, 32(%rsp)
+       leaq    32(%rsp), %rdi
+       movq    %rbx, (%rsp)
+       movq    $42, 40(%rsp)
        movl    $0, 168(%rax)
-       cmpq    %rbx, %rax
-       je      .L35
        movq    %rax, 32(%rsp)
        movq    16(%rsp), %rax
-       movq    %rax, 48(%rsp)
-       movl    $42, %eax
-.L36:
-       leaq    32(%rsp), %rdi
-       movq    %rax, 40(%rsp)
-       movq    %rbx, (%rsp)
        movq    $0, 8(%rsp)
+       movq    %rax, 48(%rsp)
        movl    $0, 16(%rsp)
        call=20=20=20
_ZNSt7__cxx1112basic_stringIwSt11char_traitsIwESaIwEE10_M_disposeEv
        movq    %rsp, %rdi
@@ -261,17 +254,10 @@
        popq    %rbx
        .cfi_def_cfa_offset 8
        ret
-.L35:
+.L36:
        .cfi_restore_state
-       movl    $4, %ecx
-       movl    $43, %edx
-       movq    %rbx, %rsi
-       call    __wmemcpy_chk
-       movq    8(%rsp), %rax
-       jmp     .L36
-.L38:
        movq    %rax, %rbx
-       jmp     .L37
+       jmp     .L35
        .globl  __gxx_personality_v0
        .section        .gcc_except_table,"a",@progbits
 .LLSDA1811:
@@ -282,7 +268,7 @@
 .LLSDACSB1811:
        .uleb128 .LEHB0-.LFB1811
        .uleb128 .LEHE0-.LEHB0
-       .uleb128 .L38-.LFB1811
+       .uleb128 .L36-.LFB1811
        .uleb128 0
 .LLSDACSE1811:
        .section        .text.startup
@@ -294,7 +280,7 @@
        .type   main.cold, @function
 main.cold:
 .LFSB1811:
-.L37:
+.L35:
        .cfi_def_cfa_offset 80
        .cfi_offset 3, -16
        movq    %rsp, %rdi=