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-rw-r--r--src/passes/AlignmentLowering.cpp214
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diff --git a/src/passes/AlignmentLowering.cpp b/src/passes/AlignmentLowering.cpp
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+++ b/src/passes/AlignmentLowering.cpp
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+/*
+ * Copyright 2017 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//
+// Lowers unaligned loads and stores into aligned loads and stores
+// that are smaller. This leaves only aligned operations.
+//
+
+#include "ir/bits.h"
+#include "pass.h"
+#include "wasm-builder.h"
+#include "wasm.h"
+
+namespace wasm {
+
+struct AlignmentLowering : public WalkerPass<PostWalker<AlignmentLowering>> {
+ void visitLoad(Load* curr) {
+ if (curr->align == 0 || curr->align == curr->bytes) {
+ return;
+ }
+ Builder builder(*getModule());
+ if (curr->type == unreachable) {
+ replaceCurrent(curr->ptr);
+ return;
+ }
+ assert(curr->type == i32); // TODO: i64, f32, f64
+ auto temp = builder.addVar(getFunction(), i32);
+ Expression* ret;
+ if (curr->bytes == 2) {
+ ret = builder.makeBinary(
+ OrInt32,
+ builder.makeLoad(
+ 1, false, curr->offset, 1, builder.makeGetLocal(temp, i32), i32),
+ builder.makeBinary(ShlInt32,
+ builder.makeLoad(1,
+ false,
+ curr->offset + 1,
+ 1,
+ builder.makeGetLocal(temp, i32),
+ i32),
+ builder.makeConst(Literal(int32_t(8)))));
+ if (curr->signed_) {
+ ret = Bits::makeSignExt(ret, 2, *getModule());
+ }
+ } else if (curr->bytes == 4) {
+ if (curr->align == 1) {
+ ret = builder.makeBinary(
+ OrInt32,
+ builder.makeBinary(
+ OrInt32,
+ builder.makeLoad(
+ 1, false, curr->offset, 1, builder.makeGetLocal(temp, i32), i32),
+ builder.makeBinary(ShlInt32,
+ builder.makeLoad(1,
+ false,
+ curr->offset + 1,
+ 1,
+ builder.makeGetLocal(temp, i32),
+ i32),
+ builder.makeConst(Literal(int32_t(8))))),
+ builder.makeBinary(
+ OrInt32,
+ builder.makeBinary(ShlInt32,
+ builder.makeLoad(1,
+ false,
+ curr->offset + 2,
+ 1,
+ builder.makeGetLocal(temp, i32),
+ i32),
+ builder.makeConst(Literal(int32_t(16)))),
+ builder.makeBinary(ShlInt32,
+ builder.makeLoad(1,
+ false,
+ curr->offset + 3,
+ 1,
+ builder.makeGetLocal(temp, i32),
+ i32),
+ builder.makeConst(Literal(int32_t(24))))));
+ } else if (curr->align == 2) {
+ ret = builder.makeBinary(
+ OrInt32,
+ builder.makeLoad(
+ 2, false, curr->offset, 2, builder.makeGetLocal(temp, i32), i32),
+ builder.makeBinary(ShlInt32,
+ builder.makeLoad(2,
+ false,
+ curr->offset + 2,
+ 2,
+ builder.makeGetLocal(temp, i32),
+ i32),
+ builder.makeConst(Literal(int32_t(16)))));
+ } else {
+ WASM_UNREACHABLE();
+ }
+ } else {
+ WASM_UNREACHABLE();
+ }
+ replaceCurrent(
+ builder.makeBlock({builder.makeSetLocal(temp, curr->ptr), ret}));
+ }
+
+ void visitStore(Store* curr) {
+ if (curr->align == 0 || curr->align == curr->bytes) {
+ return;
+ }
+ Builder builder(*getModule());
+ if (curr->type == unreachable) {
+ replaceCurrent(builder.makeBlock(
+ {builder.makeDrop(curr->ptr), builder.makeDrop(curr->value)}));
+ return;
+ }
+ assert(curr->value->type == i32); // TODO: i64, f32, f64
+ auto tempPtr = builder.addVar(getFunction(), i32);
+ auto tempValue = builder.addVar(getFunction(), i32);
+ auto* block =
+ builder.makeBlock({builder.makeSetLocal(tempPtr, curr->ptr),
+ builder.makeSetLocal(tempValue, curr->value)});
+ if (curr->bytes == 2) {
+ block->list.push_back(
+ builder.makeStore(1,
+ curr->offset,
+ 1,
+ builder.makeGetLocal(tempPtr, i32),
+ builder.makeGetLocal(tempValue, i32),
+ i32));
+ block->list.push_back(builder.makeStore(
+ 1,
+ curr->offset + 1,
+ 1,
+ builder.makeGetLocal(tempPtr, i32),
+ builder.makeBinary(ShrUInt32,
+ builder.makeGetLocal(tempValue, i32),
+ builder.makeConst(Literal(int32_t(8)))),
+ i32));
+ } else if (curr->bytes == 4) {
+ if (curr->align == 1) {
+ block->list.push_back(
+ builder.makeStore(1,
+ curr->offset,
+ 1,
+ builder.makeGetLocal(tempPtr, i32),
+ builder.makeGetLocal(tempValue, i32),
+ i32));
+ block->list.push_back(builder.makeStore(
+ 1,
+ curr->offset + 1,
+ 1,
+ builder.makeGetLocal(tempPtr, i32),
+ builder.makeBinary(ShrUInt32,
+ builder.makeGetLocal(tempValue, i32),
+ builder.makeConst(Literal(int32_t(8)))),
+ i32));
+ block->list.push_back(builder.makeStore(
+ 1,
+ curr->offset + 2,
+ 1,
+ builder.makeGetLocal(tempPtr, i32),
+ builder.makeBinary(ShrUInt32,
+ builder.makeGetLocal(tempValue, i32),
+ builder.makeConst(Literal(int32_t(16)))),
+ i32));
+ block->list.push_back(builder.makeStore(
+ 1,
+ curr->offset + 3,
+ 1,
+ builder.makeGetLocal(tempPtr, i32),
+ builder.makeBinary(ShrUInt32,
+ builder.makeGetLocal(tempValue, i32),
+ builder.makeConst(Literal(int32_t(24)))),
+ i32));
+ } else if (curr->align == 2) {
+ block->list.push_back(
+ builder.makeStore(2,
+ curr->offset,
+ 2,
+ builder.makeGetLocal(tempPtr, i32),
+ builder.makeGetLocal(tempValue, i32),
+ i32));
+ block->list.push_back(builder.makeStore(
+ 2,
+ curr->offset + 2,
+ 2,
+ builder.makeGetLocal(tempPtr, i32),
+ builder.makeBinary(ShrUInt32,
+ builder.makeGetLocal(tempValue, i32),
+ builder.makeConst(Literal(int32_t(16)))),
+ i32));
+ } else {
+ WASM_UNREACHABLE();
+ }
+ } else {
+ WASM_UNREACHABLE();
+ }
+ block->finalize();
+ replaceCurrent(block);
+ }
+};
+
+Pass* createAlignmentLoweringPass() { return new AlignmentLowering(); }
+
+} // namespace wasm
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