llvm-6502/test/CodeGen/Thumb2/2010-11-22-EpilogueBug.ll
Evan Cheng ab5c703fdb 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
2010-11-22 18:12:04 +00:00

35 lines
644 B
LLVM

; rdar://8465407
; RUN: llc < %s -mtriple=thumbv7-apple-darwin | FileCheck %s
%struct.buf = type opaque
declare void @bar() nounwind optsize
define void @foo() nounwind optsize {
; CHECK: foo:
; CHECK: push
; CHECK: add r7, sp, #4
; CHECK: sub sp, #4
entry:
%m.i = alloca %struct.buf*, align 4
br label %bb
bb:
br i1 undef, label %bb3, label %bb2
bb2:
call void @bar() nounwind optsize
br i1 undef, label %bb, label %bb3
bb3:
br i1 undef, label %return, label %bb
return:
; CHECK: %return
; 'mov sp, r7' would have left sp in an invalid state
; CHECK-NOT: mov sp, r7
; CHECK-NOT: sub, sp, #4
; CHECK: add sp, #4
ret void
}