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Enable TrapUnreachable in LLVM.

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Enable LLVM's TrapUnreachable flag, which tells it to translate
`unreachable` instructions into hardware trap instructions, rather
than allowing control flow to "fall through" into whatever code
happens to follow it in memory.
This commit is contained in:
Dan Gohman 2017-11-10 11:00:52 -08:00
parent 75d25acd97
commit d9f0e88f19
1 changed files with 6 additions and 0 deletions
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6
src/rustllvm/PassWrapper.cpp
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@ -398,6 +398,12 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
Options.DataSections = DataSections;
Options.FunctionSections = FunctionSections;
// Tell LLVM to translate `unreachable` into an explicit trap instruction.
// This limits the extent of possible undefined behavior in some cases, as it
// prevents control flow from "falling through" into whatever code happens to
// be layed out next in memory.
Options.TrapUnreachable = true;
TargetMachine *TM = TheTarget->createTargetMachine(
Trip.getTriple(), RealCPU, Feature, Options, RM, CM, OptLevel);
return wrap(TM);