fixup! fixup! [BOLT][AArch64] Add support for compact code model

Author: maksfb

bolt/test/AArch64/compact-code-model.s

@@ -2,40 +2,84 @@
 ## model.
 
 # RUN: llvm-mc -filetype=obj -triple aarch64-unknown-unknown %s -o %t.o
+# RUN: link_fdata %s %t.o %t.fdata
+# RUN: llvm-strip --strip-unneeded %t.o
 # RUN: %clang %cflags %t.o -o %t.exe -Wl,-q -static
-# RUN: llvm-bolt %t.exe -o %t.bolt --split-functions --split-strategy=randomN \
+# RUN: llvm-bolt %t.exe -o %t.bolt --data %t.fdata --split-functions \
 # RUN:   --keep-nops --compact-code-model
-# RUN: llvm-objdump -d --disassemble-symbols=_start %t.bolt | FileCheck %s
-# RUN: llvm-nm -n %t.bolt | FileCheck %s --check-prefix=CHECK-NM
+# RUN: llvm-objdump -d \
+# RUN:   --disassemble-symbols=_start,_start.cold.0,foo,foo.cold.0 %t.bolt \
+# RUN:   | FileCheck %s
+# RUN: llvm-nm -nS %t.bolt | FileCheck %s --check-prefix=CHECK-NM
 
-## _start will be split and its main fragment will be separated from other
-## fragments by large_function() which is over 1MB.
+## Fragments of _start and foo will be separated by large_function which is over
+## 1MB in size - larger than all conditional branches can cover requiring branch
+## relaxation.
 
 # CHECK-NM: _start
-# CHECK-NM-NEXT: large_function
-# CHECK-NM-NEXT: _start.cold
+# CHECK-NM: foo
+# CHECK-NM: 0000000000124f84 T large_function
+# CHECK-NM: _start.cold.0
+# CHECK-NM: foo.cold.0
 
   .text
   .globl _start
   .type _start, %function
 _start:
+# CHECK: <_start>:
+# FDATA: 0 [unknown] 0 1 _start 0 0 100
   .cfi_startproc
-  cmp  x1, 1
-  b.hi  .L1
-# CHECK: b.hi
+  cmp  x0, 1
+  b.eq  .L0
+# CHECK: b.eq
 # CHECK-NEXT: b
 # CHECK-NEXT: b
 
   bl large_function
-.L1:
+.L0:
   ret  x30
   .cfi_endproc
 .size _start, .-_start
 
+## Check that long branch in foo() is reused during relaxation. I.e. we should
+## see just one branch to the cold fragment.
+
+  .globl foo
+  .type foo, %function
+foo:
+# CHECK: <foo>:
+# FDATA: 0 [unknown] 0 1 foo 0 0 100
+  .cfi_startproc
+  cmp x0, 0
+.T0:
+  b.eq .ERROR
+# CHECK: b {{.*}} <foo.cold.0>
+# CHECK-NOT: b {{.*}} <foo.cold.0>
+# FDATA: 1 foo #.T0# 1 foo #.T1# 0 100
+.T1:
+  bl large_function
+  cmp x0, 1
+.T2:
+  b.eq .ERROR
+# FDATA: 1 foo #.T2# 1 foo #.T3# 0 100
+.T3:
+  mov x1, x0
+  mov x0, 0
+  ret x30
+
+# CHECK: <foo.cold.0>:
+# CHECK-NEXT: mov x0, #0x1
+# CHECK-NEXT: ret
+.ERROR:
+  mov x0, 1
+  ret x30
+  .cfi_endproc
+.size foo, .-foo
 
   .globl large_function
   .type large_function, %function
 large_function:
+# FDATA: 0 [unknown] 0 1 large_function 0 0 100
   .cfi_startproc
   .rept 300000
     nop