diff options
Diffstat (limited to 'llvm/lib/Transforms/Utils/Local.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Utils/Local.cpp | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp index bd8b7c45d1a..75eda97d0a3 100644 --- a/llvm/lib/Transforms/Utils/Local.cpp +++ b/llvm/lib/Transforms/Utils/Local.cpp @@ -1310,7 +1310,7 @@ static bool markAliveBlocks(Function &F, // Assumptions that are known to be false are equivalent to unreachable. // Also, if the condition is undefined, then we make the choice most // beneficial to the optimizer, and choose that to also be unreachable. - if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BBI)) + if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BBI)) { if (II->getIntrinsicID() == Intrinsic::assume) { bool MakeUnreachable = false; if (isa<UndefValue>(II->getArgOperand(0))) @@ -1327,6 +1327,24 @@ static bool markAliveBlocks(Function &F, } } + if (II->getIntrinsicID() == Intrinsic::experimental_guard) { + // A call to the guard intrinsic bails out of the current compilation + // unit if the predicate passed to it is false. If the predicate is a + // constant false, then we know the guard will bail out of the current + // compile unconditionally, so all code following it is dead. + // + // Note: unlike in llvm.assume, it is not "obviously profitable" for + // guards to treat `undef` as `false` since a guard on `undef` can + // still be useful for widening. + if (auto *CI = dyn_cast<ConstantInt>(II->getArgOperand(0))) + if (CI->isZero() && !isa<UnreachableInst>(II->getNextNode())) { + changeToUnreachable(II->getNextNode(), /*UseLLVMTrap=*/ false); + Changed = true; + break; + } + } + } + if (CallInst *CI = dyn_cast<CallInst>(BBI)) { if (CI->doesNotReturn()) { // If we found a call to a no-return function, insert an unreachable |
