S390: enable forced long branches as an option

As an example, kEagerWithResumeDeoptExitSize is always expected to
emit a 6 byte instruction "brcl", however, if the branch offset
is small enough, brc (a 4 byte instruction) might get emitted.

We need a way to force the emission of brcl at times like above.

Change-Id: Ic42c1ad80098067df6a0049bdde20e90f12ef1b0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2578061Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#71668}

src/codegen/s390/assembler-s390.cc

@@ -633,9 +633,10 @@ void Assembler::load_label_offset(Register r1, Label* L) {
 }
 
 // Pseudo op - branch on condition
-void Assembler::branchOnCond(Condition c, int branch_offset, bool is_bound) {
+void Assembler::branchOnCond(Condition c, int branch_offset, bool is_bound,
+                             bool force_long_branch) {
   int offset_in_halfwords = branch_offset / 2;
-  if (is_bound && is_int16(offset_in_halfwords)) {
+  if (is_bound && is_int16(offset_in_halfwords) && !force_long_branch) {
     brc(c, Operand(offset_in_halfwords));  // short jump
   } else {
     brcl(c, Operand(offset_in_halfwords));  // long jump

src/codegen/s390/assembler-s390.h

@@ -948,17 +948,20 @@ class V8_EXPORT_PRIVATE Assembler : public AssemblerBase {
   }
 
   // Conditional Branch Instruction - Generates either BRC / BRCL
-  void branchOnCond(Condition c, int branch_offset, bool is_bound = false);
+  void branchOnCond(Condition c, int branch_offset, bool is_bound = false,
+                    bool force_long_branch = false);
 
   // Helpers for conditional branch to Label
-  void b(Condition cond, Label* l, Label::Distance dist = Label::kFar) {
+  void b(Condition cond, Label* l, Label::Distance dist = Label::kFar,
+         bool force_long_branch = false) {
     branchOnCond(cond, branch_offset(l),
-                 l->is_bound() || (dist == Label::kNear));
+                 l->is_bound() || (dist == Label::kNear), force_long_branch);
   }
 
   void bc_short(Condition cond, Label* l, Label::Distance dist = Label::kFar) {
     b(cond, l, Label::kNear);
   }
+  void bc_long(Condition cond, Label* l) { b(cond, l, Label::kFar, true); }
   // Helpers for conditional branch to Label
   void beq(Label* l, Label::Distance dist = Label::kFar) { b(eq, l, dist); }
   void bne(Label* l, Label::Distance dist = Label::kFar) { b(ne, l, dist); }

src/codegen/s390/macro-assembler-s390.cc

@@ -4707,8 +4707,8 @@ void TurboAssembler::CallForDeoptimization(Builtins::Name target, int,
                 ? Deoptimizer::kLazyDeoptExitSize
                 : Deoptimizer::kNonLazyDeoptExitSize);
   if (kind == DeoptimizeKind::kEagerWithResume) {
-    b(ret);
-    DCHECK_LE(SizeOfCodeGeneratedSince(exit),
+    bc_long(Condition::al, ret);
+    DCHECK_EQ(SizeOfCodeGeneratedSince(exit),
               Deoptimizer::kEagerWithResumeDeoptExitSize);
   }
 }