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/Thumb2/2009-08-06-SpDecBug.ll b/test/CodeGen/Thumb2/2009-08-06-SpDecBug.ll
index f26c6d1..550b3ef 100644
--- a/test/CodeGen/Thumb2/2009-08-06-SpDecBug.ll
+++ b/test/CodeGen/Thumb2/2009-08-06-SpDecBug.ll
@@ -5,8 +5,13 @@
define hidden i32 @__gcov_execlp(i8* %path, i8* %arg, ...) nounwind {
entry:
; CHECK: __gcov_execlp:
-; CHECK: mov sp, r7
-; CHECK: sub sp, #4
+; CHECK: sub sp, #8
+; CHECK: push
+; CHECK: add r7, sp, #4
+; CHECK: subs r4, r7, #4
+; CHECK: mov sp, r4
+; CHECK-NOT: mov sp, r7
+; CHECK: add sp, #8
call void @__gcov_flush() nounwind
br i1 undef, label %bb5, label %bb
diff --git a/test/CodeGen/Thumb2/2010-08-10-VarSizedAllocaBug.ll b/test/CodeGen/Thumb2/2010-08-10-VarSizedAllocaBug.ll
index abcf13a..41f7f29 100644
--- a/test/CodeGen/Thumb2/2010-08-10-VarSizedAllocaBug.ll
+++ b/test/CodeGen/Thumb2/2010-08-10-VarSizedAllocaBug.ll
@@ -5,6 +5,10 @@
define internal fastcc i32 @Callee(i32 %i) nounwind {
entry:
; CHECK: Callee:
+; CHECK: push
+; CHECK: mov r4, sp
+; CHECK: sub.w r12, r4, #1000
+; CHECK: mov sp, r12
%0 = icmp eq i32 %i, 0 ; <i1> [#uses=1]
br i1 %0, label %bb2, label %bb
@@ -17,9 +21,11 @@
ret i32 %4
bb2: ; preds = %entry
-; Must restore sp from fp here
-; CHECK: mov sp, r7
-; CHECK: sub sp, #8
+; Must restore sp from fp here. Make sure not to leave sp in a temporarily invalid
+; state though. rdar://8465407
+; CHECK-NOT: mov sp, r7
+; CHECK: sub.w r4, r7, #8
+; CHECK: mov sp, r4
; CHECK: pop
ret i32 0
}
diff --git a/test/CodeGen/Thumb2/2010-11-22-EpilogueBug.ll b/test/CodeGen/Thumb2/2010-11-22-EpilogueBug.ll
new file mode 100644
index 0000000..313728c
--- /dev/null
+++ b/test/CodeGen/Thumb2/2010-11-22-EpilogueBug.ll
@@ -0,0 +1,34 @@
+; 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
+}