Clarify ARM calling conventions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151113 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index 88eb67f54fb8126553d95f003c1b7df422c74db7..ea4baab95c50a9d3cc2477ba18a150486e7e82fe 100644 (file)
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -1401,6 +1401,8 @@ bool ARMBaseInstrInfo::isSchedulingBoundary(const MachineInstr *MI,
   // stack slot reference to depend on the instruction that does the
   // modification.
   // Calls don't actually change the stack pointer, even if they have imp-defs.
+  // No ARM calling conventions change the stack pointer. (X86 calling
+  // conventions sometimes do).
   if (!MI->isCall() && MI->definesRegister(ARM::SP))
     return true;