deps: V8: cherry-pick 482e5c7750b3

Original commit message:

    Merged: [wasm-simd] Fix loading fp pair registers

    We were incorrectly clearing the high reg from the list of regs to load.
    The intention was to prevent double (and incorrect) loading - loading
    128 bits from the low fp and the loading 128 bits from the high fp.
    But this violates the assumption that the two regs in a pair would be
    set or unset at the same time.

    The fix here is to introduce a new enum for register loads, a nop, which
    does nothing. The high fp of the fp pair will be tied to this nop, so as
    we iterate down the reglist, we load 128 bits using the low fp, then
    don't load anything for the high fp.

    Bug: chromium:1161654
    (cherry picked from commit 8c698702ced0de085aa91370d8cb44deab3fcf54)

    (cherry picked from commit ffd6ff5a61b9343ccc62e6c03b71a33682c6084d)

    Change-Id: Ib8134574b24f74f24ca9efd34b3444173296d8f1
    No-Try: true
    No-Presubmit: true
    No-Tree-Checks: true
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2619416
    Commit-Queue: Zhi An Ng <zhin@chromium.org>
    Reviewed-by: Clemens Backes <clemensb@chromium.org>
    Cr-Original-Commit-Position: refs/branch-heads/8.8@{#28}
    Cr-Original-Branched-From: 2dbcdc105b963ee2501c82139eef7e0603977ff0-refs/heads/8.8.278@{#1}
    Cr-Original-Branched-From: 366d30c99049b3f1c673f8a93deb9f879d0fa9f0-refs/heads/master@{#71094}
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2649176
    Reviewed-by: Victor-Gabriel Savu <vsavu@google.com>
    Commit-Queue: Achuith Bhandarkar <achuith@chromium.org>
    Cr-Commit-Position: refs/branch-heads/8.6@{#55}
    Cr-Branched-From: a64aed2333abf49e494d2a5ce24bbd14fff19f60-refs/heads/8.6.395@{#1}
    Cr-Branched-From: a626bc036236c9bf92ac7b87dc40c9e538b087e3-refs/heads/master@{#69472}

Refs: https://github.com/v8/v8/commit/482e5c7750b3ae2f923b507518f6bfe40486ee59

PR-URL: https://github.com/nodejs/node/pull/38275
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Shelley Vohr <codebytere@gmail.com>

2 files changed, 67 insertions, 4 deletions

diff --git a/deps/v8/src/wasm/baseline/liftoff-assembler.cc b/deps/v8/src/wasm/baseline/liftoff-assembler.cc
index 923d375064c..c505cf7e6d1 100644
--- a/deps/v8/src/wasm/baseline/liftoff-assembler.cc
+++ b/deps/v8/src/wasm/baseline/liftoff-assembler.cc
@@ -37,6 +37,7 @@ class StackTransferRecipe {
 
   struct RegisterLoad {
     enum LoadKind : uint8_t {
+      kNop,           // no-op, used for high fp of a fp pair.
       kConstant,      // load a constant value into a register.
       kStack,         // fill a register from a stack slot.
       kLowHalfStack,  // fill a register from the low half of a stack slot.
@@ -63,6 +64,10 @@ class StackTransferRecipe {
       return {half == kLowWord ? kLowHalfStack : kHighHalfStack, kWasmI32,
               offset};
     }
+    static RegisterLoad Nop() {
+      // ValueType does not matter.
+      return {kNop, kWasmI32, 0};
+    }
 
    private:
     RegisterLoad(LoadKind kind, ValueType type, int32_t value)
@@ -217,11 +222,11 @@ class StackTransferRecipe {
           RegisterLoad::HalfStack(stack_offset, kHighWord);
     } else if (dst.is_fp_pair()) {
       DCHECK_EQ(kWasmS128, type);
-      // load_dst_regs_.set above will set both low and high fp regs.
-      // But unlike gp_pair, we load a kWasm128 in one go in ExecuteLoads.
-      // So unset the top fp register to skip loading it.
-      load_dst_regs_.clear(dst.high());
+      // Only need register_load for low_gp since we load 128 bits at one go.
+      // Both low and high need to be set in load_dst_regs_ but when iterating
+      // over it, both low and high will be cleared, so we won't load twice.
       *register_load(dst.low()) = RegisterLoad::Stack(stack_offset, type);
+      *register_load(dst.high()) = RegisterLoad::Nop();
     } else {
       *register_load(dst) = RegisterLoad::Stack(stack_offset, type);
     }
@@ -318,6 +323,8 @@ class StackTransferRecipe {
     for (LiftoffRegister dst : load_dst_regs_) {
       RegisterLoad* load = register_load(dst);
       switch (load->kind) {
+        case RegisterLoad::kNop:
+          break;
         case RegisterLoad::kConstant:
           asm_->LoadConstant(dst, load->type == kWasmI64
                                       ? WasmValue(int64_t{load->value})
diff --git a/deps/v8/test/mjsunit/regress/wasm/regress-1161654.js b/deps/v8/test/mjsunit/regress/wasm/regress-1161654.js
new file mode 100644
index 00000000000..93f2c3b556f
--- /dev/null
+++ b/deps/v8/test/mjsunit/regress/wasm/regress-1161654.js
@@ -0,0 +1,56 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --wasm-staging
+
+// This is a fuzzer-generated test case that exposed a bug in Liftoff that only
+// affects ARM, where the fp register aliasing is different from other archs.
+// We were inncorrectly clearing the the high fp register in a LiftoffRegList
+// indicating registers to load, hitting a DCHECK.
+load('test/mjsunit/wasm/wasm-module-builder.js');
+
+const builder = new WasmModuleBuilder();
+builder.addMemory(19, 32, false);
+builder.addGlobal(kWasmI32, 0);
+builder.addType(makeSig([], []));
+builder.addType(makeSig([kWasmI64, kWasmS128, kWasmF32], [kWasmI32]));
+// Generate function 1 (out of 5).
+builder.addFunction(undefined, 0 /* sig */)
+  .addBodyWithEnd([
+// signature: v_v
+// body:
+kExprI32Const, 0x05,  // i32.const
+kExprReturn,  // return
+kExprUnreachable,  // unreachable
+kExprEnd,  // end @5
+]);
+// Generate function 4 (out of 5).
+builder.addFunction(undefined, 1 /* sig */)
+  .addBodyWithEnd([
+// signature: i_lsf
+// body:
+kExprLocalGet, 0x01,  // local.get
+kExprLocalGet, 0x01,  // local.get
+kExprGlobalGet, 0x00,  // global.get
+kExprDrop,  // drop
+kExprLoop, kWasmStmt,  // loop @8
+  kExprLoop, 0x00,  // loop @10
+    kExprI32Const, 0x01,  // i32.const
+    kExprMemoryGrow, 0x00,  // memory.grow
+    kExprI64LoadMem8U, 0x00, 0x70,  // i64.load8_u
+    kExprLoop, 0x00,  // loop @19
+      kExprCallFunction, 0x00,  // call function #0: v_v
+      kExprEnd,  // end @23
+    kExprI64Const, 0xf1, 0x24,  // i64.const
+    kExprGlobalGet, 0x00,  // global.get
+    kExprDrop,  // drop
+    kExprBr, 0x00,  // br depth=0
+    kExprEnd,  // end @32
+  kExprEnd,  // end @33
+kExprI32Const, 0x5b,  // i32.const
+kExprReturn,  // return
+kExprEnd,  // end @37
+]);
+// Instantiation is enough to cause a crash.
+const instance = builder.instantiate();