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
llvm-svn: 119977
2010-11-22 19:12:04 +01:00
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; rdar://8465407
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2012-01-04 02:55:04 +01:00
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; RUN: llc < %s -mtriple=thumbv7-apple-ios | FileCheck %s
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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
llvm-svn: 119977
2010-11-22 19:12:04 +01:00
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%struct.buf = type opaque
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declare void @bar() nounwind optsize
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define void @foo() nounwind optsize {
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; CHECK: foo:
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; CHECK: push
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2011-03-11 22:52:04 +01:00
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; CHECK: mov r7, sp
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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
llvm-svn: 119977
2010-11-22 19:12:04 +01:00
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; CHECK: sub sp, #4
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entry:
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%m.i = alloca %struct.buf*, align 4
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br label %bb
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bb:
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br i1 undef, label %bb3, label %bb2
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bb2:
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call void @bar() nounwind optsize
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br i1 undef, label %bb, label %bb3
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bb3:
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br i1 undef, label %return, label %bb
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return:
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; CHECK: %return
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; 'mov sp, r7' would have left sp in an invalid state
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; CHECK-NOT: mov sp, r7
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; CHECK-NOT: sub, sp, #4
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; CHECK: add sp, #4
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ret void
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}
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