[BOLT] Check for !isTailCall in isUnconditionalBranch

Add !isTailCall in isUnconditionalBranch check in order to sync the x86
and aarch64 and fix the fixDoubleJumps pass on aarch64.

Vladislav Khmelevsky,
Advanced Software Technology Lab, Huawei

Differential Revision: https://reviews.llvm.org/D122929

Author: yota9

bolt/include/bolt/Core/MCPlusBuilder.h

@@ -353,7 +353,7 @@ class MCPlusBuilder {
   }
 
   virtual bool isUnconditionalBranch(const MCInst &Inst) const {
-    return Analysis->isUnconditionalBranch(Inst);
+    return Analysis->isUnconditionalBranch(Inst) && !isTailCall(Inst);
   }
 
   virtual bool isIndirectBranch(const MCInst &Inst) const {

bolt/lib/Target/X86/X86MCPlusBuilder.cpp

@@ -78,10 +78,6 @@ class X86MCPlusBuilder : public MCPlusBuilder {
     return Analysis->isBranch(Inst) && !isTailCall(Inst);
   }
 
-  bool isUnconditionalBranch(const MCInst &Inst) const override {
-    return Analysis->isUnconditionalBranch(Inst) && !isTailCall(Inst);
-  }
-
   bool isNoop(const MCInst &Inst) const override {
     return X86::isNOP(Inst.getOpcode());
   }

bolt/test/AArch64/ext-double-jump.s

@@ -0,0 +1,31 @@
+# This test checks that remove double jumps pass works properly with
+# non-local branches.
+
+# RUN: llvm-mc -filetype=obj -triple aarch64-unknown-unknown %s -o %t.o
+# RUN: %clang %cflags -nostartfiles -nodefaultlibs %t.o -o %t.exe -Wl,-q
+# RUN: llvm-bolt %t.exe -o %t.bolt -peepholes=double-jumps
+
+  .text
+  .align 4
+  .global dummy1
+  .type dummy1, %function
+dummy1:
+  mov x2, x0
+  ret
+  .size dummy1, .-dummy1
+
+  .global dummy2
+  .type dummy2, %function
+dummy2:
+  mov x1, x0
+  ret
+  .size dummy2, .-dummy2
+
+  .global _start
+  .type _start, %function
+_start:
+  cbz  x10, 1f
+  b dummy1
+1:
+  b dummy2
+  .size _start, .-_start