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[wasm] Alignment information of wasm programs cannot be trusted

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This CL removes code which is based on the assumption that if
WebAssembly code says that memory accesses are aligned, that they are
really aligned. On arm, memory accesses crashed when this assumption
was violated.

Most likely this CL will cause a performance regression on arm. At the
moment we plan to fix this regression eventually by using arm NEON
instructions in V8.

R=titzer@chromium.org

Change-Id: Ibb60fa1ef0173c13af813a3cb7eb26bfa2a847c2
Reviewed-on: https://chromium-review.googlesource.com/451297
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44179}
This commit is contained in:
Andreas Haas 2017-03-23 11:29:25 +01:00 committed by Commit Bot
parent ddcdbf6fef
commit 53af0d1ad3
3 changed files with 66 additions and 10 deletions
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12
src/compiler/wasm-compiler.cc
View File

@ -3016,11 +3016,8 @@ Node* WasmGraphBuilder::LoadMem(wasm::ValueType type, MachineType memtype,
if (!FLAG_wasm_trap_handler || !V8_TRAP_HANDLER_SUPPORTED) {
BoundsCheckMem(memtype, index, offset, position);
}
bool aligned = static_cast<int>(alignment) >=
ElementSizeLog2Of(memtype.representation());
if (aligned ||
jsgraph()->machine()->UnalignedLoadSupported(memtype, alignment)) {
if (jsgraph()->machine()->UnalignedLoadSupported(memtype, alignment)) {
if (FLAG_wasm_trap_handler && V8_TRAP_HANDLER_SUPPORTED) {
DCHECK(FLAG_wasm_guard_pages);
Node* position_node = jsgraph()->Int32Constant(position);
@ -3070,17 +3067,12 @@ Node* WasmGraphBuilder::StoreMem(MachineType memtype, Node* index,
if (!FLAG_wasm_trap_handler || !V8_TRAP_HANDLER_SUPPORTED) {
BoundsCheckMem(memtype, index, offset, position);
}
StoreRepresentation rep(memtype.representation(), kNoWriteBarrier);
bool aligned = static_cast<int>(alignment) >=
ElementSizeLog2Of(memtype.representation());
#if defined(V8_TARGET_BIG_ENDIAN)
val = BuildChangeEndianness(val, memtype);
#endif
if (aligned ||
jsgraph()->machine()->UnalignedStoreSupported(memtype, alignment)) {
if (jsgraph()->machine()->UnalignedStoreSupported(memtype, alignment)) {
if (FLAG_wasm_trap_handler && V8_TRAP_HANDLER_SUPPORTED) {
Node* position_node = jsgraph()->Int32Constant(position);
store = graph()->NewNode(

16
test/cctest/wasm/test-run-wasm-64.cc
View File

@ -1528,6 +1528,22 @@ WASM_EXEC_TEST(StoreMem_offset_oob_i64) {
}
}
WASM_EXEC_TEST(UnalignedInt64Load) {
WasmRunner<uint64_t> r(execution_mode);
r.module().AddMemoryElems<int64_t>(8);
BUILD(r, WASM_LOAD_MEM_ALIGNMENT(MachineType::Int64(), WASM_ONE, 3));
r.Call();
}
WASM_EXEC_TEST(UnalignedInt64Store) {
WasmRunner<int32_t> r(execution_mode);
r.module().AddMemoryElems<uint64_t>(8);
BUILD(r, WASM_SEQ(WASM_STORE_MEM_ALIGNMENT(MachineType::Int64(), WASM_ONE, 3,
WASM_I64V_1(1)),
WASM_I32V_1(12)));
r.Call();
}
#define ADD_CODE(vec, ...) \
do { \
byte __buf[] = {__VA_ARGS__}; \

48
test/cctest/wasm/test-run-wasm.cc
View File

@ -1092,6 +1092,54 @@ WASM_EXEC_TEST(LoadStoreLoad) {
}
}
WASM_EXEC_TEST(UnalignedFloat32Load) {
WasmRunner<float> r(execution_mode);
r.module().AddMemoryElems<float>(8);
BUILD(r, WASM_LOAD_MEM_ALIGNMENT(MachineType::Float32(), WASM_ONE, 2));
r.Call();
}
WASM_EXEC_TEST(UnalignedFloat64Load) {
WasmRunner<double> r(execution_mode);
r.module().AddMemoryElems<double>(8);
BUILD(r, WASM_LOAD_MEM_ALIGNMENT(MachineType::Float64(), WASM_ONE, 3));
r.Call();
}
WASM_EXEC_TEST(UnalignedInt32Load) {
WasmRunner<uint32_t> r(execution_mode);
r.module().AddMemoryElems<uint32_t>(8);
BUILD(r, WASM_LOAD_MEM_ALIGNMENT(MachineType::Int32(), WASM_ONE, 2));
r.Call();
}
WASM_EXEC_TEST(UnalignedInt32Store) {
WasmRunner<int32_t> r(execution_mode);
r.module().AddMemoryElems<uint32_t>(8);
BUILD(r, WASM_SEQ(WASM_STORE_MEM_ALIGNMENT(MachineType::Int32(), WASM_ONE, 2,
WASM_I32V_1(1)),
WASM_I32V_1(12)));
r.Call();
}
WASM_EXEC_TEST(UnalignedFloat32Store) {
WasmRunner<int32_t> r(execution_mode);
r.module().AddMemoryElems<float>(8);
BUILD(r, WASM_SEQ(WASM_STORE_MEM_ALIGNMENT(MachineType::Float32(), WASM_ONE,
2, WASM_F32(1.0)),
WASM_I32V_1(12)));
r.Call();
}
WASM_EXEC_TEST(UnalignedFloat64Store) {
WasmRunner<int32_t> r(execution_mode);
r.module().AddMemoryElems<double>(8);
BUILD(r, WASM_SEQ(WASM_STORE_MEM_ALIGNMENT(MachineType::Float64(), WASM_ONE,
3, WASM_F64(1.0)),
WASM_I32V_1(12)));
r.Call();
}
WASM_EXEC_TEST(VoidReturn1) {
const int32_t kExpected = -414444;
WasmRunner<int32_t> r(execution_mode);