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deps: V8: cherry-pick 53784bdb8f01
Original commit message: [liftoff] Handle constant memory indexes specially This adds detection for constant memory indexes which can statically be proven to be in-bounds (because the effective offset is within the minimum memory size). In these cases, we can skip the bounds check and the out-of-line code for the trap-handler. This often saves 1-2% of code size. [email protected] Bug: v8:11802 Change-Id: I0ee094e6f1f5d132af1d6a8a7c539a4af6c3cb5e Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2919827 Commit-Queue: Clemens Backes <[email protected]> Reviewed-by: Andreas Haas <[email protected]> Cr-Commit-Position: refs/heads/master@{#74825} Refs: v8/v8@53784bd PR-URL: #39337 Reviewed-By: Matteo Collina <[email protected]> Reviewed-By: James M Snell <[email protected]>
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‎common.gypi

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -36,7 +36,7 @@
3636

3737
# Reset this number to 0 on major V8 upgrades.
3838
# Increment by one for each non-official patch applied to deps/v8.
39-
'v8_embedder_string': '-node.12',
39+
'v8_embedder_string': '-node.13',
4040

4141
##### V8 defaults for Node.js #####
4242

‎deps/v8/src/wasm/baseline/liftoff-compiler.cc

Lines changed: 98 additions & 42 deletions
Original file line numberDiff line numberDiff line change
@@ -2761,33 +2761,73 @@ class LiftoffCompiler {
27612761
return index;
27622762
}
27632763

2764+
bool IndexStaticallyInBounds(const LiftoffAssembler::VarState& index_slot,
2765+
int access_size, uintptr_t* offset) {
2766+
if (!index_slot.is_const()) return false;
2767+
2768+
// Potentially zero extend index (which is a 32-bit constant).
2769+
const uintptr_t index = static_cast<uint32_t>(index_slot.i32_const());
2770+
const uintptr_t effective_offset = index + *offset;
2771+
2772+
if (effective_offset < index // overflow
2773+
|| !base::IsInBounds<uintptr_t>(effective_offset, access_size,
2774+
env_->min_memory_size)) {
2775+
return false;
2776+
}
2777+
2778+
*offset = effective_offset;
2779+
return true;
2780+
}
2781+
27642782
void LoadMem(FullDecoder* decoder, LoadType type,
27652783
const MemoryAccessImmediate<validate>& imm,
27662784
const Value& index_val, Value* result) {
27672785
ValueKind kind = type.value_type().kind();
2786+
RegClass rc = reg_class_for(kind);
27682787
if (!CheckSupportedType(decoder, kind, "load")) return;
2769-
LiftoffRegister full_index = __ PopToRegister();
2770-
Register index = BoundsCheckMem(decoder, type.size(), imm.offset,
2771-
full_index, {}, kDontForceCheck);
2772-
if (index == no_reg) return;
27732788

27742789
uintptr_t offset = imm.offset;
2775-
LiftoffRegList pinned = LiftoffRegList::ForRegs(index);
2776-
index = AddMemoryMasking(index, &offset, &pinned);
2777-
DEBUG_CODE_COMMENT("load from memory");
2778-
Register addr = pinned.set(__ GetUnusedRegister(kGpReg, pinned)).gp();
2779-
LOAD_INSTANCE_FIELD(addr, MemoryStart, kSystemPointerSize, pinned);
2780-
RegClass rc = reg_class_for(kind);
2781-
LiftoffRegister value = pinned.set(__ GetUnusedRegister(rc, pinned));
2782-
uint32_t protected_load_pc = 0;
2783-
__ Load(value, addr, index, offset, type, pinned, &protected_load_pc, true);
2784-
if (env_->use_trap_handler) {
2785-
AddOutOfLineTrap(decoder, WasmCode::kThrowWasmTrapMemOutOfBounds,
2786-
protected_load_pc);
2790+
Register index = no_reg;
2791+
2792+
// Only look at the slot, do not pop it yet (will happen in PopToRegister
2793+
// below, if this is not a statically-in-bounds index).
2794+
auto& index_slot = __ cache_state()->stack_state.back();
2795+
if (IndexStaticallyInBounds(index_slot, type.size(), &offset)) {
2796+
__ cache_state()->stack_state.pop_back();
2797+
DEBUG_CODE_COMMENT("load from memory (constant offset)");
2798+
LiftoffRegList pinned;
2799+
Register mem = pinned.set(__ GetUnusedRegister(kGpReg, pinned)).gp();
2800+
LOAD_INSTANCE_FIELD(mem, MemoryStart, kSystemPointerSize, pinned);
2801+
LiftoffRegister value = pinned.set(__ GetUnusedRegister(rc, pinned));
2802+
__ Load(value, mem, no_reg, offset, type, pinned, nullptr, true);
2803+
__ PushRegister(kind, value);
2804+
} else {
2805+
LiftoffRegister full_index = __ PopToRegister();
2806+
index = BoundsCheckMem(decoder, type.size(), offset, full_index, {},
2807+
kDontForceCheck);
2808+
if (index == no_reg) return;
2809+
2810+
DEBUG_CODE_COMMENT("load from memory");
2811+
LiftoffRegList pinned = LiftoffRegList::ForRegs(index);
2812+
index = AddMemoryMasking(index, &offset, &pinned);
2813+
2814+
// Load the memory start address only now to reduce register pressure
2815+
// (important on ia32).
2816+
Register mem = pinned.set(__ GetUnusedRegister(kGpReg, pinned)).gp();
2817+
LOAD_INSTANCE_FIELD(mem, MemoryStart, kSystemPointerSize, pinned);
2818+
LiftoffRegister value = pinned.set(__ GetUnusedRegister(rc, pinned));
2819+
2820+
uint32_t protected_load_pc = 0;
2821+
__ Load(value, mem, index, offset, type, pinned, &protected_load_pc,
2822+
true);
2823+
if (env_->use_trap_handler) {
2824+
AddOutOfLineTrap(decoder, WasmCode::kThrowWasmTrapMemOutOfBounds,
2825+
protected_load_pc);
2826+
}
2827+
__ PushRegister(kind, value);
27872828
}
2788-
__ PushRegister(kind, value);
27892829

2790-
if (FLAG_trace_wasm_memory) {
2830+
if (V8_UNLIKELY(FLAG_trace_wasm_memory)) {
27912831
TraceMemoryOperation(false, type.mem_type().representation(), index,
27922832
offset, decoder->position());
27932833
}
@@ -2830,7 +2870,7 @@ class LiftoffCompiler {
28302870
}
28312871
__ PushRegister(kS128, value);
28322872

2833-
if (FLAG_trace_wasm_memory) {
2873+
if (V8_UNLIKELY(FLAG_trace_wasm_memory)) {
28342874
// Again load extend is different.
28352875
MachineRepresentation mem_rep =
28362876
transform == LoadTransformationKind::kExtend
@@ -2872,7 +2912,7 @@ class LiftoffCompiler {
28722912

28732913
__ PushRegister(kS128, result);
28742914

2875-
if (FLAG_trace_wasm_memory) {
2915+
if (V8_UNLIKELY(FLAG_trace_wasm_memory)) {
28762916
TraceMemoryOperation(false, type.mem_type().representation(), index,
28772917
offset, decoder->position());
28782918
}
@@ -2883,29 +2923,45 @@ class LiftoffCompiler {
28832923
const Value& index_val, const Value& value_val) {
28842924
ValueKind kind = type.value_type().kind();
28852925
if (!CheckSupportedType(decoder, kind, "store")) return;
2926+
28862927
LiftoffRegList pinned;
28872928
LiftoffRegister value = pinned.set(__ PopToRegister());
2888-
LiftoffRegister full_index = __ PopToRegister(pinned);
2889-
Register index = BoundsCheckMem(decoder, type.size(), imm.offset,
2890-
full_index, pinned, kDontForceCheck);
2891-
if (index == no_reg) return;
28922929

28932930
uintptr_t offset = imm.offset;
2894-
pinned.set(index);
2895-
index = AddMemoryMasking(index, &offset, &pinned);
2896-
DEBUG_CODE_COMMENT("store to memory");
2897-
Register addr = pinned.set(__ GetUnusedRegister(kGpReg, pinned)).gp();
2898-
LOAD_INSTANCE_FIELD(addr, MemoryStart, kSystemPointerSize, pinned);
2899-
uint32_t protected_store_pc = 0;
2900-
LiftoffRegList outer_pinned;
2901-
if (FLAG_trace_wasm_memory) outer_pinned.set(index);
2902-
__ Store(addr, index, offset, value, type, outer_pinned,
2903-
&protected_store_pc, true);
2904-
if (env_->use_trap_handler) {
2905-
AddOutOfLineTrap(decoder, WasmCode::kThrowWasmTrapMemOutOfBounds,
2906-
protected_store_pc);
2931+
Register index = no_reg;
2932+
2933+
auto& index_slot = __ cache_state()->stack_state.back();
2934+
if (IndexStaticallyInBounds(index_slot, type.size(), &offset)) {
2935+
__ cache_state()->stack_state.pop_back();
2936+
DEBUG_CODE_COMMENT("store to memory (constant offset)");
2937+
Register mem = pinned.set(__ GetUnusedRegister(kGpReg, pinned)).gp();
2938+
LOAD_INSTANCE_FIELD(mem, MemoryStart, kSystemPointerSize, pinned);
2939+
__ Store(mem, no_reg, offset, value, type, pinned, nullptr, true);
2940+
} else {
2941+
LiftoffRegister full_index = __ PopToRegister(pinned);
2942+
index = BoundsCheckMem(decoder, type.size(), imm.offset, full_index,
2943+
pinned, kDontForceCheck);
2944+
if (index == no_reg) return;
2945+
2946+
pinned.set(index);
2947+
index = AddMemoryMasking(index, &offset, &pinned);
2948+
DEBUG_CODE_COMMENT("store to memory");
2949+
uint32_t protected_store_pc = 0;
2950+
// Load the memory start address only now to reduce register pressure
2951+
// (important on ia32).
2952+
Register mem = pinned.set(__ GetUnusedRegister(kGpReg, pinned)).gp();
2953+
LOAD_INSTANCE_FIELD(mem, MemoryStart, kSystemPointerSize, pinned);
2954+
LiftoffRegList outer_pinned;
2955+
if (V8_UNLIKELY(FLAG_trace_wasm_memory)) outer_pinned.set(index);
2956+
__ Store(mem, index, offset, value, type, outer_pinned,
2957+
&protected_store_pc, true);
2958+
if (env_->use_trap_handler) {
2959+
AddOutOfLineTrap(decoder, WasmCode::kThrowWasmTrapMemOutOfBounds,
2960+
protected_store_pc);
2961+
}
29072962
}
2908-
if (FLAG_trace_wasm_memory) {
2963+
2964+
if (V8_UNLIKELY(FLAG_trace_wasm_memory)) {
29092965
TraceMemoryOperation(true, type.mem_rep(), index, offset,
29102966
decoder->position());
29112967
}
@@ -2934,7 +2990,7 @@ class LiftoffCompiler {
29342990
AddOutOfLineTrap(decoder, WasmCode::kThrowWasmTrapMemOutOfBounds,
29352991
protected_store_pc);
29362992
}
2937-
if (FLAG_trace_wasm_memory) {
2993+
if (V8_UNLIKELY(FLAG_trace_wasm_memory)) {
29382994
TraceMemoryOperation(true, type.mem_rep(), index, offset,
29392995
decoder->position());
29402996
}
@@ -4179,9 +4235,9 @@ class LiftoffCompiler {
41794235
Register addr = pinned.set(__ GetUnusedRegister(kGpReg, pinned)).gp();
41804236
LOAD_INSTANCE_FIELD(addr, MemoryStart, kSystemPointerSize, pinned);
41814237
LiftoffRegList outer_pinned;
4182-
if (FLAG_trace_wasm_memory) outer_pinned.set(index);
4238+
if (V8_UNLIKELY(FLAG_trace_wasm_memory)) outer_pinned.set(index);
41834239
__ AtomicStore(addr, index, offset, value, type, outer_pinned);
4184-
if (FLAG_trace_wasm_memory) {
4240+
if (V8_UNLIKELY(FLAG_trace_wasm_memory)) {
41854241
TraceMemoryOperation(true, type.mem_rep(), index, offset,
41864242
decoder->position());
41874243
}
@@ -4207,7 +4263,7 @@ class LiftoffCompiler {
42074263
__ AtomicLoad(value, addr, index, offset, type, pinned);
42084264
__ PushRegister(kind, value);
42094265

4210-
if (FLAG_trace_wasm_memory) {
4266+
if (V8_UNLIKELY(FLAG_trace_wasm_memory)) {
42114267
TraceMemoryOperation(false, type.mem_type().representation(), index,
42124268
offset, decoder->position());
42134269
}

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