[ptr-compr][arm64] Update poison test regex

We now have branchful decompression so this needs to be updated. Also,
the sxtw doesn't happen so it is not included in the regex.

I don't know why this didn't block the other CL's submission.

Cq-Include-Trybots: luci.v8.try:v8_linux64_pointer_compression_rel_ng
Cq-Include-Trybots: luci.v8.try:v8_linux64_arm64_pointer_compression_rel_ng
Bug: v8:7703
Change-Id: I7044878c4811f1ba39e957bfcb9bc9c77ccba172
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1706482Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62872}

test/cctest/test-poison-disasm-arm64.cc

@@ -49,7 +49,7 @@ TEST(DisasmPoisonMonomorphicLoad) {
       "b.ne",                                              // deopt if different
       "csel " + kPReg + ", xzr, " + kPReg + ", ne",        // update the poison
       "csdb",                                              // spec. barrier
-      "ldur w<<Field:[0-9]+>>, \\[<<Obj>>, #[0-9]+\\]",    // load the field
+      "ldursw x<<Field:[0-9]+>>, \\[<<Obj>>, #[0-9]+\\]",  // load the field
       "and x<<Field>>, x<<Field>>, " + kPReg,              // apply the poison
   };
 #else
@@ -109,17 +109,15 @@ TEST(DisasmPoisonPolymorphicLoad) {
       "csdb",                                            // spec. barrier
       "ldur w<<Field:[0-9]+>>, \\[<<Obj>>, #[0-9]+\\]",  // load the field
       "and x<<Field>>, x<<Field>>, " + kPReg,            // apply the poison
-      "sxtw x<<Field>>, w<<Field>>",
-      "asr w[0-9]+, w<<Field>>, #1",  // untag
-      "b",                            // goto merge point
+      "asr w[0-9]+, w<<Field>>, #1",                     // untag
+      "b",                                               // goto merge point
       // Lcase1:
       "csel " + kPReg + ", xzr, " + kPReg + ", ne",      // update the poison
       "csdb",                                            // spec. barrier
-      "ldur w<<BSt:[0-9]+>>, \\[<<Obj>>, #[0-9]+\\]",    // load backing store
+      "ldursw x<<BSt:[0-9]+>>, \\[<<Obj>>, #[0-9]+\\]",  // load backing store
+      "tbz w<<BSt>>, #0, #\\+0x8",                       // branchful decompress
+      "add x<<BSt>>, x26, x<<BSt>>",                     // Add root to ref
       "and x<<BSt>>, x<<BSt>>, " + kPReg,                // apply the poison
-      "sbfx <<Temp:x[0-9]+>>, x<<BSt>>, #0, #1",         // Decompress ref
-      "and <<Temp>>, <<Temp>>, x26",                     // Decompress ref
-      "add x<<BSt>>, <<Temp>>, w<<BSt>>, sxtw",          // Decompress ref
       "ldur w<<Prop:[0-9]+>>, \\[x<<BSt>>, #[0-9]+\\]",  // load the property
       "and x<<Prop>>, x<<Prop>>, " + kPReg,              // apply the poison
                                                          // Ldone: