<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Issue</th>
<td>
<a href=http://email.email.llvm.org/c/eJztWVmTmzgQ_jX4RWUKJM4HP2TszG6qUpXdJO8uXdiacAWE48mv35bAGE-8EzvXZmvGhQGpW62vW91qSbBK3C-cyONUI05b6XLkYBLjIIBKx1s53gsnvLEUvddOuHJwstW6bh3ywsG3cG2U3nbM5VUBhTzfHR7zuqnuJNdQzFQuW3jGqRdHJIK3USBOh06gN3vxvtxqqhVHqtSIAgDoGDkE_vGN78Qrh9x8webgF6znwZFp4hmw5_ng4gdW5uDlUCeOdYd2u0oJlFUVaG1eDdzzIiVwANUA7MkImjXI1EIDuE5pCKnMEEegBzsg-2ONpB_Gno7s7AFfj2yKCiFjnuG1kbprSgNPjAwj2QAvqCqPwNFoFzlKPYobR2gs8pyWm3mGUxxGNAoo932ehSmXNIkTngif0TQksWBBFmJi8OumKz-Y3uZvCAgAjytRWWkkc1WokmqJoNYoBTTWaTR2YhyqajZzn7ie602auwOayX1-5e9Ewvdqhebv0LyC2lshd3Bvtai6Q2gdjUeWQmqq8hbM_RJKbVcUtLmHwlspOi4Fom0rC5ZD1dKIGelQrs3jFHR_0bboa-y4ksFJHv05RoXAsw0GkanLM7UG9240hPAQj5YPh4y5non8A2vdtduP8ARSQ_enEoTM1jyj6yrLWqmRH41kXtS5bRR4Jvqo9bawUfVxOvDSotoZyeyEaGP1pKs7afp7fXPjrf2-si_EU5iDrKEpCGFnu9xXTY8rlD3b8DZqW9UHMfxxZZORCjH4cYrLn-L6ip20bPUp7n9XPnk4TvhRAzzQ4a6oR0nkCK_GNFcb8Iw0MI28fepNdUku8DELiMBM_PL9VrXoVVnKBr2uqhr9KamQjRGxkrXeApN_Fk9yMZ7wQjwwnZYWg-E_wFhZ3c9g4TTPjfHMvHSlcwKbcSh6hk2K_cWjY_zg4Jhif0bAXXl0hHhqEfLTRmjqm_ysS00whQ-dM_gpIzWJ37NmmtBHyPIqO8szUTL11dH4WVfytSzFyWzptuqzkdCn3SWasM0nM_CDRGsTQN1P_Tav2MTxIAf8kKT3ZZZ9YunsawlgOpn_L0f425Y1u0tG-k2n605fM7590QJDO9m0qiqRH1jXu3qX4QIDulS7Mee_p81GauNa-yRaR8EcNC6rT-U8V2W3n2_KbuDbwoJcoKISMjfcddWqwSteleBaeS7FStmZEnB9FlRTs8mpihp2Ps2aU76VpuKqMYAG7OAxt1VXCrPeFUqYZfIfyyXMjLZn2IVU5dBz1zbGLooZi3EO90Gvmk9Uwre-7_qu922io-AK4e9kDoMD8f9DpS5HsEWXa2X0BXGu2eNA7IOoR7gIHtjg5RTiY7J-nzn5V8Yi-Y5YFDGLopQRSjwShDzjguFMSEyzKAsSSgOWBkkQiv82FqUIPCIDzrAMecojX-CMsSBgVHqEh5FHcOqxzH-Oxacci2YuNhe6US3gMyazhL4IcHVlgLIQ-7Ef4TQLozgTwsdemsBsnoZZxtM4xl7MU1jWDCapikJp05rd2xEIvDt6_wG80vd--CxyKbQnuOZ7PsJ4PsL4GRvk5yOM5yOM5yOMX5Si_2rkTlVdi7jNqsbUMuVJGpPM51ESpzQIgxAWczTjEhamnKdJEMRhHGRn8-WljZ9gvvzdzkhmYkFESlI6o53eVs3i7442HZt1Tb64-kulatvOfqoMCcF4tl3ghKUpCSkPM0yjxOMpJnEkY9ivh4JKf5ZTJvN2Yb5RYlzKT8iKgHcnXM2-H4FaYA9jD9ZrfoKjMHETTpNQZJhniYdpSmAkJVgtd40cF3aKs2ZhRbJu0wIxV61uj0TwMcg-Ui76j6ozrXQuFyuzo1rCjgq9HL7Emf3fW7lpZGu3glRbTz-cCqFd6w7bQ0gHM4t5YQH_A3QFD64>53322</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>
Dead Code Elimination Regression at -O3 (trunk vs. 13.0.0)
</td>
</tr>
<tr>
<th>Labels</th>
<td>
new issue
</td>
</tr>
<tr>
<th>Assignees</th>
<td>
</td>
</tr>
<tr>
<th>Reporter</th>
<td>
Quarub
</td>
</tr>
</table>
<pre>
`cat case.c #7244`
[case.txt](https://github.com/llvm/llvm-project/files/7907636/case.txt)
```c
static int a[] = {1};
static int *b = &a[0];
static int **c = &b, **d = &b;
void foo(void);
static int *e() {
for (;;) {
if (a[0])
break;
if (b)
foo();
}
return *d;
}
int main() { *c = e(); }
```
`clang-f29256a64ac11cf59cea878c8d1ba9537db4f523 (trunk) -O3` can not eliminate `foo` but `clang-llvmorg-13.0.0 -O3` can.
------------------------------------------------
`clang-f29256a64ac11cf59cea878c8d1ba9537db4f523 (trunk) -O3 -S -o /dev/stdout case.c`
<details ><summary>Reduced assembly</summary><p>
```asm
main: # @main
.cfi_startproc
# %bb.0:
pushq %rax
.cfi_def_cfa_offset 16
cmpl $0, a(%rip)
movq b(%rip), %rax
je .LBB0_1
.LBB0_7:
movq %rax, b(%rip)
xorl %eax, %eax
popq %rcx
.cfi_def_cfa_offset 8
retq
.LBB0_1:
.cfi_def_cfa_offset 16
testq %rax, %rax
je .LBB0_8
# %bb.2:
movq %rax, %rcx
jmp .LBB0_3
.p2align 4, 0x90
.LBB0_8: # =>This Inner Loop Header: Depth=1
jmp .LBB0_8
.p2align 4, 0x90
.LBB0_5: # in Loop: Header=BB0_3 Depth=1
callq foo
movq b(%rip), %rax
movl a(%rip), %edx
movq %rax, %rcx
testl %edx, %edx
jne .LBB0_7
.LBB0_3: # =>This Inner Loop Header: Depth=1
testq %rcx, %rcx
jne .LBB0_5
# %bb.4: # in Loop: Header=BB0_3 Depth=1
xorl %edx, %edx
xorl %ecx, %ecx
testl %edx, %edx
je .LBB0_3
jmp .LBB0_7
.Lfunc_end0:
.size main, .Lfunc_end0-main
```
</p></details>
------------------------------------------------
`clang-llvmorg-13.0.0 -O3 -S -o /dev/stdout case.c`
<details ><summary>Reduced assembly</summary><p>
```asm
main: # @main
.cfi_startproc
# %bb.0:
xorl %eax, %eax
retq
.Lfunc_end0:
.size main, .Lfunc_end0-main
```
</p></details>
------------------------------------------------
`clang-f29256a64ac11cf59cea878c8d1ba9537db4f523 (trunk) -v`
<details ><summary>Output</summary><p>
```
clang version 14.0.0 (https://github.com/llvm/llvm-project.git f29256a64ac11cf59cea878c8d1ba9537db4f523)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /zdata/compiler_cache/clang-f29256a64ac11cf59cea878c8d1ba9537db4f523/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0
Found candidate GCC installation: /usr/lib64/gcc/x86_64-pc-linux-gnu/11.1.0
Selected GCC installation: /usr/lib64/gcc/x86_64-pc-linux-gnu/11.1.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64
```
</p></details>
------------------------------------------------
`clang-llvmorg-13.0.0 -v`
<details ><summary>Output</summary><p>
```
clang version 13.0.0 (https://github.com/llvm/llvm-project.git d7b669b3a30345cfcdb2fde2af6f48aa4b94845d)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /zdata/compiler_cache/clang-ed403e4cb2e5c9c61d2fbb44bae03c5603290bf1/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0
Found candidate GCC installation: /usr/lib64/gcc/x86_64-pc-linux-gnu/11.1.0
Selected GCC installation: /usr/lib64/gcc/x86_64-pc-linux-gnu/11.1.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64
```
</p></details>
------------------------------------------------
### Bisection
Bisected to: b52171629f567fdd120987db95ffc977207c960a
Committed by: @jaykang10
------------------------------------------------
`clang-b52171629f567fdd120987db95ffc977207c960a -O3 -S -o /dev/stdout case.c`
<details ><summary>Reduced assembly</summary><p>
```asm
main: # @main
.cfi_startproc
# %bb.0:
pushq %rax
.cfi_def_cfa_offset 16
cmpl $0, a(%rip)
movq b(%rip), %rax
je .LBB0_1
.LBB0_7:
movq %rax, b(%rip)
xorl %eax, %eax
popq %rcx
.cfi_def_cfa_offset 8
retq
.LBB0_1:
.cfi_def_cfa_offset 16
testq %rax, %rax
je .LBB0_8
# %bb.2:
movq %rax, %rcx
jmp .LBB0_3
.p2align 4, 0x90
.LBB0_8: # =>This Inner Loop Header: Depth=1
jmp .LBB0_8
.p2align 4, 0x90
.LBB0_5: # in Loop: Header=BB0_3 Depth=1
callq foo
movq b(%rip), %rax
movl a(%rip), %edx
movq %rax, %rcx
testl %edx, %edx
jne .LBB0_7
.LBB0_3: # =>This Inner Loop Header: Depth=1
testq %rcx, %rcx
jne .LBB0_5
# %bb.4: # in Loop: Header=BB0_3 Depth=1
xorl %edx, %edx
xorl %ecx, %ecx
testl %edx, %edx
je .LBB0_3
jmp .LBB0_7
.Lfunc_end0:
.size main, .Lfunc_end0-main
```
</p></details>
------------------------------------------------
Previous commit: e9c8973f1c6879a4545329afceb66cc98447574f
`clang-e9c8973f1c6879a4545329afceb66cc98447574f -O3 -S -o /dev/stdout case.c`
<details ><summary>Reduced assembly</summary><p>
```asm
main: # @main
.cfi_startproc
# %bb.0:
xorl %eax, %eax
retq
.Lfunc_end0:
.size main, .Lfunc_end0-main
```
</p></details>
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJztWVmT2jgQ_jXmRYXLlnw-8JCBzG6qUpXdJO-UTtDEV2yZMPn127KNMRN2Ark2WzOUAUvdan3d6kOyWSnuF07kcWoQp410OXIwiXEQQKfjrRzvhRPedBSzN064cnCyNaZqHPLCwbdwbbTZtszlZQ6NLNsd_uZVXd5JbqCpdCYb-I9TL45IBHejQJwOk8Bs3cX7dmOo0RzpwiAKAGBi5BD4xje-E68ccvMFm4NfsJ4HR3aIZ8Ge54OLH1iZg5dDnzj2HcbtSi2QKkvQ2t5auOdFSuAAqgXYkxEMq5HthQFwndIQ0soSR6AHO6Duw2pJP4wzHdnZA74e2RQVQtY8w20tTVsXFp4YGUayBZ5TXRyBo9EucpR6FDeu0NjkGS02c4VTHEY0Cij3fa7ClEuaxAlPhM9oGpJYsECFmFj8pm6LD3a2-RsCAsDjClSUBslM57qgRiLotUoBjbUGjZNYhyrrzdwnrud6k-HugGbyO7_ycyLhe7VC83doXkLvrZA7-G2MKNtDaB2NR5ZCGqqzBsz9ElpNm-e0vofGWylaLgWiTSNzlkHX0ooZ6dCu7N8p6P6iTd73dOtKBid59ONYFQKvGzCITF2u9BrcuzYQwkM8dnw4ZMz1bOQfWKu22X6EfyDVdH8qQUi15oquS6UaaZAfjWSeV1k3KPBs9NHO28JaV8d04KV5ubOS2Qmxi9WTqe6kne_1zY239vvOvhFPYQ6yhqEghJ2dcl_WPa5Q9mzD3ahtWR3E8MeVTUYqxODHKS5_iusrdjKyMae4_1355OE64UcN8ECHu7waJZEjvArTTG_AM9LADvL2qTfVJbnAxzpABDLxy_db3aBXRSFr9LosK_SnpELWVsRKVmYLTP5ZPMnFeMIL8UA6LToMlv8AY9XpfgYLp1lmjWfz0pXOCWzWoegZNin2F6-O9YODY4r9GQF3xdER4qlFyE9boalv8rMuNcEUPnTO4Kes1CR-z5ppQh8hy6vsLM9EydRXR-OrtuBrWYiTbOk2-rOV0JfdJZqwzScZ-EGh7QpA1af-rq50heNBDfghRe_LKvvEytnXCsA0mf8vV_jbtjW7S1b6TWuq1lyzvn2zA4Z2sm50WSA_6Fzv6lOGCwzoUu3Gmv-e1htprGvtk2gdBXPQuCg_FfNMF-1-vinagW8LG3KB8lLIzHJXZaMHr3hVgGtlmRQr3WVKwPVZUEPtIafMKzj51GtO-VbajqvWAAawg8fclm0h7H5XaGG3yX8sl5AZu5nhFFIWw8xtU1u7aGYtxjn8DnpVfKISvvV913e9bxMdBVcIfyczWByI_x8qdTmCzdvMaKsviHPtGQdiH0Q9wkXwwAY3pxAfk_X75ORfGYvkO2JRxCyKUkYo8UgQcsUFw0pITFWkgoTSgKVBEoTiv41FKQKPyIAzLEOe8sgXWDEWBIxKj_Aw8ghOPab851h8yrFoc7G90I1uAJ81WUfomwDXlBYoC7Ef-xFOVRjFSggfe2kC2TwNleJpHGMv5ilsawaTlHmujR3N7rsVCLw7ev8BvNL3fngWuRTaE9zzPT_CeH6E8TMOyM-PMJ4fYTw_wvhFJfqvWu502TaId1XVmlqmPEljonweJXFKgzAIYTNHFZewMeU8TYIgDuNAna2Xlw5-gvXyd3tGMhMLIlKS0pnRJpOLlT0dLOF0gF4Ob5XsWeat3NSy6Y411HSrdnjCgXaNOxx1ILXN2jpbXP2CUzdN273hDAnBeLZdeLEKKE0DD44bqaJJ6FNMVOKrUPhJHJNZRpnMmoV9tYlxIT-hTgTcO-FqphfYw9iDTZqf4ChM3ISDCKEwV4mHaUpg-SSYKnMtDheOh7N60UFi7aYBYqYb0xyJ4FhQcqRc9G9SZ7Q127Je_N3SumWzbuZFh_wfnuf6Ug">