diff options
Diffstat (limited to 'src/passes/OptimizeInstructions.cpp')
| -rw-r--r-- | src/passes/OptimizeInstructions.cpp | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp index 3952c765f..51a188c15 100644 --- a/src/passes/OptimizeInstructions.cpp +++ b/src/passes/OptimizeInstructions.cpp @@ -431,8 +431,8 @@ struct OptimizeInstructions curr->cast<Binary>()->right = y; return curr; } - // i32(x) <<>> (y & 32) ==> x - // i64(x) <<>> (y & 64) ==> x + // i32(x) <<>> (y & C) ==> x, where (C & 31) == 0 + // i64(x) <<>> (y & C) ==> x, where (C & 63) == 0 if (((c->type == Type::i32 && (c->value.geti32() & 31) == 0) || (c->type == Type::i64 && (c->value.geti64() & 63LL) == 0LL)) && !effects(y).hasSideEffects()) { @@ -1052,6 +1052,21 @@ private: // return binary; // } } + } else if (binary->op == RemSInt32) { + // bool(i32(x) % C_pot) ==> bool(x & (C_pot - 1)) + // bool(i32(x) % min_s) ==> bool(x & max_s) + if (auto* c = binary->right->dynCast<Const>()) { + if (c->value.isSignedMin() || + Bits::isPowerOf2(c->value.abs().geti32())) { + binary->op = AndInt32; + if (c->value.isSignedMin()) { + c->value = Literal::makeSignedMax(Type::i32); + } else { + c->value = c->value.abs().sub(Literal::makeOne(Type::i32)); + } + return binary; + } + } } if (auto* ext = Properties::getSignExtValue(binary)) { // use a cheaper zero-extent, we just care about the boolean value |