deps: V8: cherry-pick 3cc6919

Original commit message:

    PPC: fix Regex addi overflow

    using add insetad of addi when Operand is more than 16 bits long

    Change-Id: I7f9452381ed8b321ec71e68d0d90485508b69885
    Reviewed-on: https://chromium-review.googlesource.com/c/1430619
    Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
    Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
    Cr-Commit-Position: refs/heads/master@{#59049}

Refs: v8/v8@3cc6919

PR-URL: #25872
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: George Adams <george.adams@uk.ibm.com>
Reviewed-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>

Author: milad

common.gypi

@@ -33,7 +33,7 @@
 
     # Reset this number to 0 on major V8 upgrades.
     # Increment by one for each non-official patch applied to deps/v8.
-    'v8_embedder_string': '-node.50',
+    'v8_embedder_string': '-node.51',
 
     # Enable disassembler for `--print-code` v8 options
     'v8_enable_disassembler': 1,

deps/v8/src/regexp/ppc/regexp-macro-assembler-ppc.cc

@@ -142,8 +142,13 @@ int RegExpMacroAssemblerPPC::stack_limit_slack() {
 
 void RegExpMacroAssemblerPPC::AdvanceCurrentPosition(int by) {
   if (by != 0) {
-    __ addi(current_input_offset(), current_input_offset(),
-            Operand(by * char_size()));
+    if (is_int16(by * char_size())) {
+      __ addi(current_input_offset(), current_input_offset(),
+              Operand(by * char_size()));
+    } else {
+      __ mov(r0, Operand(by * char_size()));
+      __ add(current_input_offset(), r0, current_input_offset());
+    }
   }
 }
 
@@ -1272,7 +1277,12 @@ void RegExpMacroAssemblerPPC::LoadCurrentCharacterUnchecked(int cp_offset,
   Register offset = current_input_offset();
   if (cp_offset != 0) {
     // r25 is not being used to store the capture start index at this point.
-    __ addi(r25, current_input_offset(), Operand(cp_offset * char_size()));
+    if (is_int16(cp_offset * char_size())) {
+      __ addi(r25, current_input_offset(), Operand(cp_offset * char_size()));
+    } else {
+      __ mov(r25, Operand(cp_offset * char_size()));
+      __ add(r25, r25, current_input_offset());
+    }
     offset = r25;
   }
   // The lwz, stw, lhz, sth instructions can do unaligned accesses, if the CPU