Mikael Holmén via llvm-dev
2016-Feb-08 09:32 UTC
[llvm-dev] LoopIdiomRegognize vs Preserved
Hi,
I'm having problems with the LoopIdiomRegognizer crashing on me with
An asserting value handle still pointed to this value!
UNREACHABLE executed at ../lib/IR/Value.cpp:695!
If I remove
AU.addPreserved<LoopInfoWrapperPass>();
or
AU.addPreserved<AAResultsWrapperPass>();
everything goes well.
The C-code triggering this is
void foo(int a[10][10])
{
int i, j, k;
for (i = 0; i < 1; i++) {
for (j = 0; j < 2; j++) {
for (k = 0; k < 10; k++) {
a[j][k] = 42;
}
}
}
}
First LoopIdiomRecognize replaces the store in the inner loop with a
memset in the outer loop, and later, when examining the outer loop it
tries to replace that memset with an even bigger memset in the outermost
loop. But then, when removing the "old" memset, the assert blows.
I don't know LoopIdiomRecognize very well at all, is it obvious that
AAResultsWrapperPass and/or LoopInfoWrapperPass should not be preserved
here?
Regards,
Mikael
Hi Mikael,
What is your compilation command to trig the assert? I am trying to reproduce
your problem.
Thank you,
Haicheng
-----Original Message-----
From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of Mikael
Holmén via llvm-dev
Sent: Monday, February 08, 2016 4:33 AM
To: llvm-dev at lists.llvm.org
Subject: [llvm-dev] LoopIdiomRegognize vs Preserved
Hi,
I'm having problems with the LoopIdiomRegognizer crashing on me with
An asserting value handle still pointed to this value!
UNREACHABLE executed at ../lib/IR/Value.cpp:695!
If I remove
AU.addPreserved<LoopInfoWrapperPass>();
or
AU.addPreserved<AAResultsWrapperPass>();
everything goes well.
The C-code triggering this is
void foo(int a[10][10])
{
int i, j, k;
for (i = 0; i < 1; i++) {
for (j = 0; j < 2; j++) {
for (k = 0; k < 10; k++) {
a[j][k] = 42;
}
}
}
}
First LoopIdiomRecognize replaces the store in the inner loop with a memset in
the outer loop, and later, when examining the outer loop it tries to replace
that memset with an even bigger memset in the outermost loop. But then, when
removing the "old" memset, the assert blows.
I don't know LoopIdiomRecognize very well at all, is it obvious that
AAResultsWrapperPass and/or LoopInfoWrapperPass should not be preserved here?
Regards,
Mikael
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Mikael Holmén via llvm-dev
2016-Feb-09 09:19 UTC
[llvm-dev] LoopIdiomRegognize vs Preserved
Hi Haicheng, Originally I ran into this on our out-of-tree target but I managed to reproduce the crash on X86 as well now: build-all/bin/opt -S -sroa -loop-rotate -loop-deletion -licm -loop-idiom ../llvm/bugpoint-reduced-simplified.i8+.ll gives: While deleting: void % An asserting value handle still pointed to this value! UNREACHABLE executed at ../lib/IR/Value.cpp:696! 0 opt 0x0000000001752bc8 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 40 1 opt 0x0000000001751376 llvm::sys::RunSignalHandlers() + 54 2 opt 0x00000000017537ca 3 libpthread.so.0 0x00007f1909a70340 4 libc.so.6 0x00007f1908c98cc9 gsignal + 57 5 libc.so.6 0x00007f1908c9c0d8 abort + 328 6 opt 0x000000000170cddd llvm::llvm_unreachable_internal(char const*, char const*, unsigned int) + 461 7 opt 0x000000000137bd3b llvm::ValueHandleBase::ValueIsDeleted(llvm::Value*) + 1051 8 opt 0x000000000137b5db llvm::Value::~Value() + 43 9 opt 0x0000000001322319 llvm::CallInst::~CallInst() + 9 10 opt 0x000000000131e676 llvm::Instruction::eraseFromParent() + 86 11 opt 0x00000000015e8d14 12 opt 0x00000000015e8630 13 opt 0x00000000015e4e6a 14 opt 0x0000000000f5404e llvm::LPPassManager::runOnFunction(llvm::Function&) + 1086 15 opt 0x000000000134a034 llvm::FPPassManager::runOnFunction(llvm::Function&) + 516 16 opt 0x000000000134a27b llvm::FPPassManager::runOnModule(llvm::Module&) + 43 17 opt 0x000000000134a757 llvm::legacy::PassManagerImpl::run(llvm::Module&) + 903 18 opt 0x000000000062aa9e main + 8782 19 libc.so.6 0x00007f1908c83ec5 __libc_start_main + 245 20 opt 0x0000000000618bcf Stack dump: 0. Program arguments: build-all/bin/opt -S -sroa -loop-rotate -loop-deletion -licm -loop-idiom ../llvm/bugpoint-reduced-simplified.i8+.ll 1. Running pass 'Function Pass Manager' on module '../llvm/bugpoint-reduced-simplified.i8+.ll'. 2. Running pass 'Loop Pass Manager' on function '@set_array' 3. Running pass 'Recognize loop idioms' on basic block '%bb4' Abort /Mikael On 02/08/2016 05:50 PM, Haicheng Wu wrote:> Hi Mikael, > > What is your compilation command to trig the assert? I am trying to reproduce your problem. > > Thank you, > > Haicheng > > -----Original Message----- > From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of Mikael Holmén via llvm-dev > Sent: Monday, February 08, 2016 4:33 AM > To: llvm-dev at lists.llvm.org > Subject: [llvm-dev] LoopIdiomRegognize vs Preserved > > Hi, > > I'm having problems with the LoopIdiomRegognizer crashing on me with > > An asserting value handle still pointed to this value! > UNREACHABLE executed at ../lib/IR/Value.cpp:695! > > If I remove > > AU.addPreserved<LoopInfoWrapperPass>(); > > or > > AU.addPreserved<AAResultsWrapperPass>(); > > everything goes well. > > The C-code triggering this is > > void foo(int a[10][10]) > { > int i, j, k; > > for (i = 0; i < 1; i++) { > for (j = 0; j < 2; j++) { > for (k = 0; k < 10; k++) { > a[j][k] = 42; > } > } > } > } > > First LoopIdiomRecognize replaces the store in the inner loop with a memset in the outer loop, and later, when examining the outer loop it tries to replace that memset with an even bigger memset in the outermost loop. But then, when removing the "old" memset, the assert blows. > > I don't know LoopIdiomRecognize very well at all, is it obvious that AAResultsWrapperPass and/or LoopInfoWrapperPass should not be preserved here? > > Regards, > Mikael > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev > >-------------- next part -------------- define void @set_array() { %j.3 = alloca i8 %k.4 = alloca i8 br label %bb1 bb4: ; preds = %bb3 store i8 0, i8* %k.4 br label %bb5 bb6: ; preds = %bb5 %_tmp31 = sext i8 %_tmp3 to i64 %_tmp4 = mul i64 %_tmp31, 10 %_tmp5 = getelementptr i8, i8* undef, i64 %_tmp4 %_tmp6 = load i8, i8* %k.4 %_tmp7 = getelementptr i8, i8* %_tmp5, i8 %_tmp6 store i8 42, i8* %_tmp7 %_tmp8 = load i8, i8* %k.4 %_tmp9 = add i8 %_tmp8, 1 store i8 %_tmp9, i8* %k.4 br label %bb5 bb5: ; preds = %bb6, %bb4 %_tmp10 = load i8, i8* %k.4 %_tmp11 = icmp slt i8 %_tmp10, 10 %_tmp3 = load i8, i8* %j.3 br i1 %_tmp11, label %bb6, label %bb7 bb7: ; preds = %bb5 %_tmp13 = add i8 %_tmp3, 1 store i8 %_tmp13, i8* %j.3 br label %bb3 bb3: ; preds = %bb1, %bb7 %_tmp14 = load i8, i8* %j.3 %_tmp15 = icmp slt i8 %_tmp14, 2 br i1 %_tmp15, label %bb4, label %bb1 bb1: ; preds = %bb3, %0 br i1 false, label %bb3, label %bb9 bb9: ; preds = %bb1 ret void } !llvm.ident = !{!0} !0 = !{!"foo"}