Fix epilogue codegen to avoid leaving the stack pointer in an invalid
state. Previously Thumb2 would restore sp from fp like this:
mov sp, r7
sub, sp, #4
If an interrupt is taken after the 'mov' but before the 'sub', callee-saved
registers might be clobbered by the interrupt handler. Instead, try
restoring directly from sp:
add sp, #4
Or, if necessary (with VLA, etc.) use a scratch register to compute sp and
then restore it:
sub.w r4, r7, #8
mov sp, r7
rdar://8465407
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119977 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/Thumb/large-stack.ll b/test/CodeGen/Thumb/large-stack.ll
index b289484..f4dd3e0 100644
--- a/test/CodeGen/Thumb/large-stack.ll
+++ b/test/CodeGen/Thumb/large-stack.ll
@@ -12,8 +12,8 @@
; CHECK: test2:
; CHECK: ldr r0, LCPI
; CHECK: add sp, r0
-; CHECK: mov sp, r7
-; CHECK: sub sp, #4
+; CHECK: subs r4, r7, #4
+; CHECK: mov sp, r4
%tmp = alloca [ 4168 x i8 ] , align 4
ret void
}
@@ -24,8 +24,8 @@
; CHECK: add sp, r2
; CHECK: ldr r1, LCPI
; CHECK: add r1, sp
-; CHECK: mov sp, r7
-; CHECK: sub sp, #4
+; CHECK: subs r4, r7, #4
+; CHECK: mov sp, r4
%retval = alloca i32, align 4
%tmp = alloca i32, align 4
%a = alloca [805306369 x i8], align 16