MIPS: Use PC realitive instructions on r6.

src/mips/code-stubs-mips.cc

Index: src/mips/code-stubs-mips.cc
diff --git a/src/mips/code-stubs-mips.cc b/src/mips/code-stubs-mips.cc
index aab8d08e3141df0f1ef90bf6183138c58832398d..51162171a2ba992f1746a411cd65b60f650026f1 100644
--- a/src/mips/code-stubs-mips.cc
+++ b/src/mips/code-stubs-mips.cc
@@ -1125,20 +1125,21 @@ void CEntryStub::Generate(MacroAssembler* masm) {
   // we can store the address on the stack to be able to find it again and
   // we never have to restore it, because it will not change.
   { Assembler::BlockTrampolinePoolScope block_trampoline_pool(masm);
-    // This branch-and-link sequence is needed to find the current PC on mips,
-    // saved to the ra register.
-    // Use masm-> here instead of the double-underscore macro since extra
-    // coverage code can interfere with the proper calculation of ra.
+    int kNumInstructionsToJump = 4;
     Label find_ra;
-    __ bal(&find_ra);  // bal exposes branch delay slot.
-    __ nop();
-    __ bind(&find_ra);
-
     // Adjust the value in ra to point to the correct return location, 2nd
     // instruction past the real call into C code (the jalr(t9)), and push it.
     // This is the return address of the exit frame.
-    const int kNumInstructionsToJump = 5;
-    __ Addu(ra, ra, kNumInstructionsToJump * kPointerSize);
+    if (kArchVariant >= kMips32r6) {
+      __ addiupc(ra, kNumInstructionsToJump + 1);
+    } else {
+      // This branch-and-link sequence is needed to find the current PC on mips
+      // before r6, saved to the ra register.
+      __ bal(&find_ra);  // bal exposes branch delay slot.
+      __ Addu(ra, ra, kNumInstructionsToJump * Instruction::kInstrSize);
+    }
+    __ bind(&find_ra);
+
     // This spot was reserved in EnterExitFrame.
     __ sw(ra, MemOperand(sp, result_stack_size));
     // Stack space reservation moved to the branch delay slot below.