[wasm] Fix endianness issue when initializing memory

memory[1] needs to be set in LE order even on BE platforms.

Change-Id: I44620c30a25719d0d61e0f14490342ee930dbbb4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3302852Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Zhi An Ng <zhin@chromium.org>
Commit-Queue: Milad Farazmand <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/main@{#78136}

test/cctest/wasm/test-run-wasm-atomics64.cc

@@ -702,7 +702,8 @@ WASM_EXEC_TEST(I64AtomicLoadUseOnlyLowWord) {
   WasmRunner<uint32_t> r(execution_tier);
   uint64_t* memory =
       r.builder().AddMemoryElems<uint64_t>(kWasmPageSize / sizeof(uint64_t));
-  memory[1] = 0x1234567890abcdeful;
+  uint64_t initial = 0x1234567890abcdef;
+  r.builder().WriteMemory(&memory[1], initial);
   r.builder().SetHasSharedMemory();
   // Test that we can use just the low word of an I64AtomicLoad.
   BUILD(r,
@@ -716,7 +717,8 @@ WASM_EXEC_TEST(I64AtomicLoadUseOnlyHighWord) {
   WasmRunner<uint32_t> r(execution_tier);
   uint64_t* memory =
       r.builder().AddMemoryElems<uint64_t>(kWasmPageSize / sizeof(uint64_t));
-  memory[1] = 0x1234567890abcdeful;
+  uint64_t initial = 0x1234567890abcdef;
+  r.builder().WriteMemory(&memory[1], initial);
   r.builder().SetHasSharedMemory();
   // Test that we can use just the high word of an I64AtomicLoad.
   BUILD(r, WASM_I32_CONVERT_I64(WASM_I64_ROR(
@@ -731,7 +733,8 @@ WASM_EXEC_TEST(I64AtomicAddUseOnlyLowWord) {
   WasmRunner<uint32_t> r(execution_tier);
   uint64_t* memory =
       r.builder().AddMemoryElems<uint64_t>(kWasmPageSize / sizeof(uint64_t));
-  memory[1] = 0x1234567890abcdeful;
+  uint64_t initial = 0x1234567890abcdef;
+  r.builder().WriteMemory(&memory[1], initial);
   r.builder().SetHasSharedMemory();
   // Test that we can use just the low word of an I64AtomicLoad.
   BUILD(r, WASM_I32_CONVERT_I64(
@@ -745,7 +748,8 @@ WASM_EXEC_TEST(I64AtomicAddUseOnlyHighWord) {
   WasmRunner<uint32_t> r(execution_tier);
   uint64_t* memory =
       r.builder().AddMemoryElems<uint64_t>(kWasmPageSize / sizeof(uint64_t));
-  memory[1] = 0x1234567890abcdeful;
+  uint64_t initial = 0x1234567890abcdef;
+  r.builder().WriteMemory(&memory[1], initial);
   r.builder().SetHasSharedMemory();
   // Test that we can use just the high word of an I64AtomicLoad.
   BUILD(r, WASM_I32_CONVERT_I64(WASM_I64_ROR(
@@ -760,7 +764,8 @@ WASM_EXEC_TEST(I64AtomicCompareExchangeUseOnlyLowWord) {
   WasmRunner<uint32_t> r(execution_tier);
   uint64_t* memory =
       r.builder().AddMemoryElems<uint64_t>(kWasmPageSize / sizeof(uint64_t));
-  memory[1] = 0x1234567890abcdeful;
+  uint64_t initial = 0x1234567890abcdef;
+  r.builder().WriteMemory(&memory[1], initial);
   r.builder().SetHasSharedMemory();
   // Test that we can use just the low word of an I64AtomicLoad.
   BUILD(r, WASM_I32_CONVERT_I64(WASM_ATOMICS_TERNARY_OP(
@@ -774,7 +779,8 @@ WASM_EXEC_TEST(I64AtomicCompareExchangeUseOnlyHighWord) {
   WasmRunner<uint32_t> r(execution_tier);
   uint64_t* memory =
       r.builder().AddMemoryElems<uint64_t>(kWasmPageSize / sizeof(uint64_t));
-  memory[1] = 0x1234567890abcdeful;
+  uint64_t initial = 0x1234567890abcdef;
+  r.builder().WriteMemory(&memory[1], initial);
   r.builder().SetHasSharedMemory();
   // Test that we can use just the high word of an I64AtomicLoad.
   BUILD(r, WASM_I32_CONVERT_I64(WASM_I64_ROR(
@@ -790,7 +796,8 @@ WASM_EXEC_TEST(I64AtomicExchangeUseOnlyLowWord) {
   WasmRunner<uint32_t> r(execution_tier);
   uint64_t* memory =
       r.builder().AddMemoryElems<uint64_t>(kWasmPageSize / sizeof(uint64_t));
-  memory[1] = 0x1234567890abcdeful;
+  uint64_t initial = 0x1234567890abcdef;
+  r.builder().WriteMemory(&memory[1], initial);
   r.builder().SetHasSharedMemory();
   // Test that we can use just the low word of an I64AtomicLoad.
   BUILD(r, WASM_I32_CONVERT_I64(WASM_ATOMICS_BINOP(
@@ -804,7 +811,8 @@ WASM_EXEC_TEST(I64AtomicExchangeUseOnlyHighWord) {
   WasmRunner<uint32_t> r(execution_tier);
   uint64_t* memory =
       r.builder().AddMemoryElems<uint64_t>(kWasmPageSize / sizeof(uint64_t));
-  memory[1] = 0x1234567890abcdeful;
+  uint64_t initial = 0x1234567890abcdef;
+  r.builder().WriteMemory(&memory[1], initial);
   r.builder().SetHasSharedMemory();
   // Test that we can use just the high word of an I64AtomicLoad.
   BUILD(r, WASM_I32_CONVERT_I64(WASM_I64_ROR(