Index: llvm/trunk/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
===================================================================
--- llvm/trunk/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
+++ llvm/trunk/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
@@ -635,16 +635,6 @@
       CompactUnwindEncoding |= (StackAdjust & 0xFF) << 16;
       CompactUnwindEncoding |= RegEnc & CU::UNWIND_BP_FRAME_REGISTERS;
     } else {
-      // If the amount of the stack allocation is the size of a register, then
-      // we "push" the RAX/EAX register onto the stack instead of adjusting the
-      // stack pointer with a SUB instruction. We don't support the push of the
-      // RAX/EAX register with compact unwind. So we check for that situation
-      // here.
-      if ((NumDefCFAOffsets == SavedRegIdx + 1 &&
-           StackSize - PrevStackSize == 1) ||
-          (Instrs.size() == 1 && NumDefCFAOffsets == 1 && StackSize == 2))
-        return CU::UNWIND_MODE_DWARF;
-
       SubtractInstrIdx += InstrOffset;
       ++StackAdjust;
 
Index: llvm/trunk/test/MC/X86/compact-unwind.s
===================================================================
--- llvm/trunk/test/MC/X86/compact-unwind.s
+++ llvm/trunk/test/MC/X86/compact-unwind.s
@@ -64,6 +64,24 @@
 	retq
 	.cfi_endproc
 
+# Check that a adjustment through a push %rax is the same as a sub.
+
+# CHECK:   Entry at offset 0x40:
+# CHECK-NEXT:     start:                0x2a _testrax
+# CHECK-NEXT:     length:               0x5
+# CHECK-NEXT:     compact encoding:     0x02020000
+	.globl	_testrax
+_testrax:                               ## @testrax
+	.cfi_startproc
+## %bb.0:                               ## %entry
+	pushq	%rax
+Ltmp15:
+	.cfi_def_cfa_offset 16
+	xorl	%eax, %eax
+	popq	%rax
+	retq
+	.cfi_endproc
+
 	.section	__TEXT,__cstring,cstring_literals
 L_.str:                                 ## @.str
 	.asciz	"%d\n"