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[InstCombine] Support sext in foldLogicCastConstant
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Authored by craig.topper on Aug 2 2017, 10:56 AM.

Details

Summary

This adds support for sext in foldLogicCastConstant. This is a prerequisite for D36214.

Not clear if the test changes are a win or not.

Could reduce the handling to only do all 0s/1s constants which would be sufficient for what's needed in D36214.

Diff Detail

Repository
rL LLVM

Event Timeline

spatel accepted this revision.Aug 2 2017, 12:02 PM

LGTM. I think it makes sense for the same reason as the zext case.

lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
1092 ↗(On Diff #109381)

Update comment to 'zext or sext'.

test/Transforms/InstCombine/cast.ll
591–592 ↗(On Diff #109381)

Not this patch, but seems odd that we'd choose to sext to the larger type and mask rather than sext+zext?

This revision is now accepted and ready to land.Aug 2 2017, 12:02 PM
This revision was automatically updated to reflect the committed changes.
eastig reopened this revision.Aug 10 2017, 9:11 AM
eastig added a subscriber: eastig.

Hi,

This patch causes an assertion failure on the attached test.ll. Could you please have a look at it?

$ ../bin/opt test.ll -instcombine -S
opt: ../lib/IR/Constants.cpp:1551: static llvm::Constant* llvm::ConstantExpr::getTrunc(llvm::Constant*, llvm::Type*, bool): Assertion `C->getType()->getScalarSizeInBits() > Ty->getScalarSizeInBits()&& "SrcTy must be larger than DestTy for Trunc!"' failed.
#0 0x000000000360ab38 llvm::sys::PrintStackTrace(llvm::raw_ostream&) /home/evgast01/local/repos/llvm12/build.d/../lib/Support/Unix/Signals.inc:398:0
#1 0x000000000360abc9 PrintStackTraceSignalHandler(void*) /home/evgast01/local/repos/llvm12/build.d/../lib/Support/Unix/Signals.inc:462:0
#2 0x0000000003608fde llvm::sys::RunSignalHandlers() /home/evgast01/local/repos/llvm12/build.d/../lib/Support/Signals.cpp:49:0
#3 0x000000000360a4bb SignalHandler(int) /home/evgast01/local/repos/llvm12/build.d/../lib/Support/Unix/Signals.inc:252:0
#4 0x00007f37c51e1330 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x10330)
#5 0x00007f37c3fc9c37 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x36c37)
#6 0x00007f37c3fcd028 abort (/lib/x86_64-linux-gnu/libc.so.6+0x3a028)
#7 0x00007f37c3fc2bf6 (/lib/x86_64-linux-gnu/libc.so.6+0x2fbf6)
#8 0x00007f37c3fc2ca2 (/lib/x86_64-linux-gnu/libc.so.6+0x2fca2)
#9 0x0000000002e19bc5 llvm::ConstantExpr::getTrunc(llvm::Constant*, llvm::Type*, bool) /home/evgast01/local/repos/llvm12/build.d/../lib/IR/Constants.cpp:1553:0
#10 0x0000000003103c73 getSelectCondition(llvm::Value*, llvm::Value*, llvm::IRBuilder<llvm::TargetFolder, llvm::IRBuilderCallbackInserter>&) /home/evgast01/local/repos/llvm12/build.d/../lib/Transforms/InstCombine/InstCombineAndOrXor.cpp:1498:0
#11 0x0000000003103f10 matchSelectFromAndOr(llvm::Value*, llvm::Value*, llvm::Value*, llvm::Value*, llvm::IRBuilder<llvm::TargetFolder, llvm::IRBuilderCallbackInserter>&) /home/evgast01/local/repos/llvm12/build.d/../lib/Transforms/InstCombine/InstCombineAndOrXor.cpp:1522:0
#12 0x00000000031071fe llvm::InstCombiner::visitOr(llvm::BinaryOperator&) /home/evgast01/local/repos/llvm12/build.d/../lib/Transforms/InstCombine/InstCombineAndOrXor.cpp:1989:0
#13 0x00000000030e9dbb llvm::InstVisitor<llvm::InstCombiner, llvm::Instruction*>::visit(llvm::Instruction&) /home/evgast01/local/repos/llvm12/build.d/../include/llvm/IR/Instruction.def:146:0
#14 0x00000000030e48a5 llvm::InstCombiner::run() /home/evgast01/local/repos/llvm12/build.d/../lib/Transforms/InstCombine/InstructionCombining.cpp:2971:0
#15 0x00000000030e5a86 combineInstructionsOverFunction(llvm::Function&, llvm::InstCombineWorklist&, llvm::AAResults*, llvm::AssumptionCache&, llvm::TargetLibraryInfo&, llvm::DominatorTree&, llvm::OptimizationRemarkEmitter&, bool, llvm::LoopInfo*) /home/evgast01/local/repos/llvm12/build.d/../lib/Transforms/InstCombine/InstructionCombining.cpp:3203:0
#16 0x00000000030e5e0f llvm::InstructionCombiningPass::runOnFunction(llvm::Function&) /home/evgast01/local/repos/llvm12/build.d/../lib/Transforms/InstCombine/InstructionCombining.cpp:3262:0
#17 0x0000000002f14f46 llvm::FPPassManager::runOnFunction(llvm::Function&) /home/evgast01/local/repos/llvm12/build.d/../lib/IR/LegacyPassManager.cpp:1514:0
#18 0x0000000002f150d9 llvm::FPPassManager::runOnModule(llvm::Module&) /home/evgast01/local/repos/llvm12/build.d/../lib/IR/LegacyPassManager.cpp:1535:0
#19 0x0000000002f15474 (anonymous namespace)::MPPassManager::runOnModule(llvm::Module&) /home/evgast01/local/repos/llvm12/build.d/../lib/IR/LegacyPassManager.cpp:1591:0
#20 0x0000000002f15bcb llvm::legacy::PassManagerImpl::run(llvm::Module&) /home/evgast01/local/repos/llvm12/build.d/../lib/IR/LegacyPassManager.cpp:1694:0
#21 0x0000000002f15e0b llvm::legacy::PassManager::run(llvm::Module&) /home/evgast01/local/repos/llvm12/build.d/../lib/IR/LegacyPassManager.cpp:1726:0
#22 0x00000000015ee1ae main /home/evgast01/local/repos/llvm12/build.d/../tools/opt/opt.cpp:759:0
#23 0x00007f37c3fb4f45 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21f45)
#24 0x00000000015c7f89 _start (../bin/opt+0x15c7f89)
Stack dump:
0.      Program arguments: ../bin/opt test.ll -instcombine -S 
1.      Running pass 'Function Pass Manager' on module 'test.ll'.
2.      Running pass 'Combine redundant instructions' on function '@dotests_115'
Aborted

This revision is now accepted and ready to land.Aug 10 2017, 9:11 AM
craig.topper closed this revision.Aug 10 2017, 10:50 AM

Fixed the assertion failure in r310639. Looks like a latent bug that was always there. I added a reduced test case with the commit that doesn't rely on any sext folding.

Fixed the assertion failure in r310639. Looks like a latent bug that was always there. I added a reduced test case with the commit that doesn't rely on any sext folding.

Thank you, Craig, for fixing it quickly.