diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/passes/OptimizeInstructions.cpp | 36 |
1 files changed, 30 insertions, 6 deletions
diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp index 6dbb1b7e8..c81119f75 100644 --- a/src/passes/OptimizeInstructions.cpp +++ b/src/passes/OptimizeInstructions.cpp @@ -305,6 +305,24 @@ static int32_t lowBitMask(int32_t bits) { return ret >> (32 - bits); } +// performs a dynCast on the fallthrough value, i.e., looks through +// too and block fallthroughs, etc. +template<typename T> +T* getFallthroughDynCast(Expression* curr) { + if (T* ret = curr->dynCast<T>()) { + return ret; + } + if (auto* set = curr->dynCast<SetLocal>()) { + if (set->isTee()) return getFallthroughDynCast<T>(set->value); + } else if (auto* block = curr->dynCast<Block>()) { + // if no name, we can't be broken to, and then can look at the fallthrough + if (!block->name.is() && block->list.size() > 0) { + return getFallthroughDynCast<T>(block->list.back()); + } + } + return nullptr; +} + // Main pass class struct OptimizeInstructions : public WalkerPass<PostWalker<OptimizeInstructions, UnifiedExpressionVisitor<OptimizeInstructions>>> { bool isFunctionParallel() override { return true; } @@ -359,11 +377,14 @@ struct OptimizeInstructions : public WalkerPass<PostWalker<OptimizeInstructions, if (auto* ext = getAlmostSignExt(binary)) { Index extraShifts; auto bits = getAlmostSignExtBits(binary, extraShifts); - auto* load = ext->dynCast<Load>(); + auto* load = getFallthroughDynCast<Load>(ext); // pattern match a load of 8 bits and a sign extend using a shl of 24 then shr_s of 24 as well, etc. if (load && ((load->bytes == 1 && bits == 8) || (load->bytes == 2 && bits == 16))) { - load->signed_ = true; - return removeAlmostSignExt(binary); + // if the value falls through, we can't alter the load, as it might be captured in a tee + if (load->signed_ == true || load == ext) { + load->signed_ = true; + return removeAlmostSignExt(binary); + } } // if the sign-extend input cannot have a sign bit, we don't need it if (getMaxBits(ext) + extraShifts < bits) { @@ -405,11 +426,14 @@ struct OptimizeInstructions : public WalkerPass<PostWalker<OptimizeInstructions, return binary->left; } // small loads do not need to be masted, the load itself masks - if (auto* load = binary->left->dynCast<Load>()) { + if (auto* load = getFallthroughDynCast<Load>(binary->left)) { if ((load->bytes == 1 && mask == 0xff) || (load->bytes == 2 && mask == 0xffff)) { - load->signed_ = false; - return load; + // if the value falls through, we can't alter the load, as it might be captured in a tee + if (load->signed_ == false || load == binary->left) { + load->signed_ = false; + return binary->left; + } } } else if (mask == 1 && Properties::emitsBoolean(binary->left)) { // (bool) & 1 does not need the outer mask |