<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Issue</th>
<td>
<a href=https://github.com/llvm/llvm-project/issues/74572>74572</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>
Crash in CanonicalizeFreezeInLoops pass due to double removal of one freeze instruction
</td>
</tr>
<tr>
<th>Labels</th>
<td>
new issue
</td>
</tr>
<tr>
<th>Assignees</th>
<td>
</td>
</tr>
<tr>
<th>Reporter</th>
<td>
Friedrich20
</td>
</tr>
</table>
<pre>
Following is the basic block that causes the crash. Here `%.fr = freeze i8 %add32` has been found twice by the pass CanonicalizeFreezeInLoops, and then the compiling crashes in second removal since the freeze instruction has already gone.
### IR snippet
```
for.cond26: ; preds = %entry, %for.inc48
%2 = phi i8 [ 0, %entry ], [ %add32, %for.inc48 ]
%inc4971 = phi i8 [ poison, %entry ], [ %inc49, %for.inc48 ]
%f.addr.0.f.addr.0.f.addr.0.62 = phi i8 [ 0, %entry ], [ %add32, %for.inc48 ]
%3 = phi i8 [ %b.promoted, %entry ], [ %8, %for.inc48 ]
%4 = phi i8 [ 9, %entry ], [ %inc49, %for.inc48 ], !dbg !46
%tobool27.not = icmp eq i8 %4, 0, !dbg !49
br i1 %tobool27.not, label %for.end50, label %for.body28, !dbg !49
```
### debug-only=canon-freeze
```
canonfr: PHI: %2 = phi i8 [ 0, %entry ], [ %add32, %for.inc48 ]
canonfr: found: %.fr = freeze i8 %add32, !dbg !54
canonfr: PHI: %f.addr.0.f.addr.0.f.addr.0.62 = phi i8 [ 0, %entry ], [ %add32, %for.inc48 ]
canonfr: found: %.fr = freeze i8 %add32, !dbg !54
canonfr: PHI: %4 = phi i8 [ 9, %entry ], [ %inc49, %for.inc48 ], !dbg !46
canonfr: drop flags: %add32 = add i8 %add, %f.addr.0.f.addr.0.f.addr.0.62, !dbg !50
canonfr: drop flags: %add32 = add i8 %add, %f.addr.0.f.addr.0.f.addr.0.62, !dbg !50
canonfr: removing %.fr = freeze i8 %add32, !dbg !54
canonfr: removing <badref> = freeze
```
### crash report (part of)
```
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0. Program arguments: /home/taowei/llvm15/output/llvm-binary-Debug/bin/clang-15 -cc1 -triple hitspv1 -S -disable-free -clear-ast-before-backend -main-file-name fail_compile_abort_exception_Oz_1700004753_110151.c -mrelocation-model static -mframe-pointer=none -relaxed-aliasing -fmath-errno -ffp-contract=on -fno-rounding-math -fno-verbose-asm -no-integrated-as -mconstructor-aliases -fno-use-init-array -mllvm -enable-dfa-jump-thread=true -mllvm -no-stack-coloring=true -target-cpu hitspv150 -mllvm -machine-sink-split=0 -mllvm -treat-scalable-fixed-error-as-warning -debug-info-kind=constructor -dwarf-version=2 -debugger-tuning=gdb -fno-dwarf-directory-asm -fcoverage-compilation-dir=/home/taowei/dts/4434canonicalize -resource-dir /home/taowei/llvm15/output/llvm-binary-Debug/lib/clang/15.0.4 -internal-isystem /home/taowei/llvm15/output/llvm-binary-Debug/bin/../hitspv150-elf/include -Oz -Wno-int-conversion -w -fdebug-compilation-dir=/home/taowei/dts/4434canonicalize -fstack-size-section -ferror-limit 19 -stack-protector 2 -fno-builtin -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-slp -fdollars-in-identifiers -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/fail_compile_abort_exception_Oz_1700004753_110151-4c11f7.s -x c fail_compile_abort_exception_Oz_1700004753_110151.c
1. <eof> parser at end of file
2. Code generation
3. Running pass 'Function Pass Manager' on module 'fail_compile_abort_exception_Oz_1700004753_110151.c'.
4. Running pass 'Loop Pass Manager' on function '@e'
5. Running pass 'Canonicalize Freeze Instructions in Loops' on basic block '%for.cond26'
#0 0x0000564176acf5b8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) /home/taowei/llvm15/llvm-15.0.4/llvm/lib/Support/Unix/Signals.inc:569:0
#1 0x0000564176acf66f PrintStackTraceSignalHandler(void*) /home/taowei/llvm15/llvm-15.0.4/llvm/lib/Support/Unix/Signals.inc:636:0
#2 0x0000564176acd2f6 llvm::sys::RunSignalHandlers() /home/taowei/llvm15/llvm-15.0.4/llvm/lib/Support/Signals.cpp:103:0
#3 0x0000564176acef25 SignalHandler(int) /home/taowei/llvm15/llvm-15.0.4/llvm/lib/Support/Unix/Signals.inc:407:0
#4 0x00007f1ebeb56520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
#5 0x0000564174c1c1de llvm::Value::getType() const /home/taowei/llvm15/llvm-15.0.4/llvm/include/llvm/IR/Value.h:255:0
#6 0x00005641761391db llvm::Value::doRAUW(llvm::Value*, llvm::Value::ReplaceMetadataUses) /home/taowei/llvm15/llvm-15.0.4/llvm/lib/IR/Value.cpp:502:0
#7 0x0000564176139368 llvm::Value::replaceAllUsesWith(llvm::Value*) /home/taowei/llvm15/llvm-15.0.4/llvm/lib/IR/Value.cpp:531:0
#8 0x0000564176b1b5c3 (anonymous namespace)::CanonicalizeFreezeInLoopsImpl::run() /home/taowei/llvm15/llvm-15.0.4/llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp:196:0
#9 0x0000564176b1b783 (anonymous namespace)::CanonicalizeFreezeInLoops::runOnLoop(llvm::Loop*, llvm::LPPassManager&) /home/taowei/llvm15/llvm-15.0.4/llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp:224:0
#10 0x000056417c1588a4 llvm::LPPassManager::runOnFunction(llvm::Function&) /home/taowei/llvm15/llvm-15.0.4/llvm/lib/Analysis/LoopPass.cpp:195:0
#11 0x0000564176087462 llvm::FPPassManager::runOnFunction(llvm::Function&) /home/taowei/llvm15/llvm-15.0.4/llvm/lib/IR/LegacyPassManager.cpp:1430:0
#12 0x000056417608770b llvm::FPPassManager::runOnModule(llvm::Module&) /home/taowei/llvm15/llvm-15.0.4/llvm/lib/IR/LegacyPassManager.cpp:1476:0
#13 0x0000564176087b33 (anonymous namespace)::MPPassManager::runOnModule(llvm::Module&) /home/taowei/llvm15/llvm-15.0.4/llvm/lib/IR/LegacyPassManager.cpp:1545:0
#14 0x0000564176082b55 llvm::legacy::PassManagerImpl::run(llvm::Module&) /home/taowei/llvm15/llvm-15.0.4/llvm/lib/IR/LegacyPassManager.cpp:535:0
#15 0x00005641760883bd llvm::legacy::PassManager::run(llvm::Module&) /home/taowei/llvm15/llvm-15.0.4/llvm/lib/IR/LegacyPassManager.cpp:1673:0
```
</pre>
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