[BOLT] Fix shrinkwrapping bug when changing frame alignment

Summary:
This fixes a bug with shrink wrapping when trying to move
push-pops in a function where we are not allowed to modify the
stack layout for alignment reasons. In this bug, we failed to
propagate alignment requirement upwards in the call graph from
function A to B when: (1) there is a cycle in the call graph and
(2) the distance from A to B is greater than 1 in the call graph
and (3) there is a node in the path from A to B, not including
A or B, that does not access parameters in the stack.

(cherry picked from FBD25315977)

bolt/src/Passes/FrameAnalysis.cpp

@@ -363,7 +363,7 @@ bool FrameAnalysis::updateArgsTouchedFor(const BinaryFunction &BF, MCInst &Inst,
     FunctionsRequireAlignment.insert(&BF);
   }
   if (Iter == ArgsTouchedMap.end())
-    return false;
+    return Changed;
 
   if (CurOffset == StackPointerTracking::EMPTY ||
       CurOffset == StackPointerTracking::SUPERPOSITION) {

bolt/test/X86/shrinkwrapping-alignment.s

@@ -0,0 +1,88 @@
+# This reproduces a bug with shrink wrapping when trying to move
+# push-pops in a function where we are not allowed to modify the
+# stack layout for alignment reasons. In this bug, we failed to
+# propagate alignment requirement upwards in the call graph for
+# some functions when there is a cycle in the call graph.
+
+# REQUIRES: system-linux
+
+# RUN: llvm-mc -filetype=obj -triple x86_64-unknown-unknown \
+# RUN:   %s -o %t.o
+# RUN: link_fdata %s %t.o %t.fdata
+# Delete our BB symbols so BOLT doesn't mark them as entry points
+# RUN: strip --strip-unneeded %t.o
+# RUN: %host_cc %t.o -o %t.exe -Wl,-q
+
+# RUN: llvm-bolt %t.exe -relocs=1 -frame-opt=all -print-finalized \
+# RUN:   -lite=0 -print-only=main -data %t.fdata -o %t.out | FileCheck %s
+
+# RUN: %t.out
+
+# CHECK: BOLT-INFO: Shrink wrapping moved 1 spills inserting load/stores and 0 spills inserting push/pops
+
+  .text
+  .globl bar
+  .type bar, %function
+  .p2align 4
+bar:
+# FDATA: 0 [unknown] 0 1 bar 0 0 510
+  pushq %rbp
+  movq  %rsp, %rbp
+  pushq %rbx                  # We save rbx here, but there is an
+                              # opportunity to move it to .BB2
+  subq  $0x18, %rsp
+  cmpl  $0x2, %edi
+.J1:
+  jb    .BBend
+# FDATA: 1 bar #.J1# 1 bar #.BB2# 0 10
+# FDATA: 1 bar #.J1# 1 bar #.BBend# 0 500
+.BB2:
+  movq $2, %rbx               # Use rbx in a cold block
+  xorq %rax, %rax
+  movb mystring, %al
+  addq %rbx, %rax
+  movb %al, mystring
+  leaq mystring, %rdi
+  #callq puts
+
+.BBend:
+  addq $0x18, %rsp
+  pop %rbx                    # Restore
+  xorq %rax, %rax
+  cmpq  $0x0, %rax
+  jne  .BBnever
+  jmp  .BBbarend
+.BBnever:
+  # This is a path that is never executed, but we add a call to main here
+  # to force a cycle in the call graph and to require us to have an aligned
+  # stack
+  callq main
+.BBbarend:
+  leaveq
+  retq
+  .size bar, .-bar
+
+# Frame alignedness information needs to be transmitted from foo to main to bar
+  .globl  main
+  .type main, %function
+  .p2align  4
+main:
+  # Call a function that requires an aligned stack
+  callq foo
+  # Call a function that can be shrink-wrapped
+  callq bar
+  retq
+  .size main, .-main
+
+# Frame alignedness information needs to be transmitted from foo to main to bar
+  .globl  foo
+  .type foo, %function
+  .p2align  4
+foo:
+  # Use an instruction that requires an aligned stack
+  movdqa -0x10(%rsp), %xmm0
+  retq
+  .size foo, .-foo
+
+  .data
+mystring: .asciz "0 is rbx mod 10 contents in decimal\n"