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DeadArgElim: don't eliminate arguments from naked functions

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Differential Revision: http://reviews.llvm.org/D12534

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@246564 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hans Wennborg 2015-09-01 18:06:46 +00:00
parent 20264d6c67
commit e1478f87af
2 changed files with 52 additions and 0 deletions
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21
lib/Transforms/IPO/DeadArgumentElimination.cpp
View File

@ -198,6 +198,13 @@ bool DAE::DeleteDeadVarargs(Function &Fn) {
if (Fn.hasAddressTaken())
return false;
// Don't touch naked functions. The assembly might be using an argument, or
// otherwise rely on the frame layout in a way that this analysis will not
// see.
if (Fn.hasFnAttribute(Attribute::Naked)) {
return false;
}
// Okay, we know we can transform this function if safe. Scan its body
// looking for calls marked musttail or calls to llvm.vastart.
for (Function::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) {
@ -345,6 +352,12 @@ bool DAE::RemoveDeadArgumentsFromCallers(Function &Fn)
if (Fn.hasLocalLinkage() && !Fn.getFunctionType()->isVarArg())
return false;
// Don't touch naked functions. The assembly might be using an argument, or
// otherwise rely on the frame layout in a way that this analysis will not
// see.
if (Fn.hasFnAttribute(Attribute::Naked))
return false;
if (Fn.use_empty())
return false;
@ -543,6 +556,14 @@ void DAE::SurveyFunction(const Function &F) {
return;
}
// Don't touch naked functions. The assembly might be using an argument, or
// otherwise rely on the frame layout in a way that this analysis will not
// see.
if (F.hasFnAttribute(Attribute::Naked)) {
MarkLive(F);
return;
}
unsigned RetCount = NumRetVals(&F);
// Assume all return values are dead
typedef SmallVector<Liveness, 5> RetVals;

31
test/Transforms/DeadArgElim/naked_functions.ll Normal file
View File

@ -0,0 +1,31 @@
; RUN: opt -S -deadargelim %s | FileCheck %s
; Don't eliminate dead arugments from naked functions.
; CHECK: define internal i32 @naked(i32 %x)
define internal i32 @naked(i32 %x) #0 {
tail call void asm sideeffect inteldialect "mov eax, [esp + $$4]\0A\09ret", "~{eax},~{dirflag},~{fpsr},~{flags}"()
unreachable
}
; Don't eliminate dead varargs from naked functions.
; CHECK: define internal i32 @naked_va(i32 %x, ...)
define internal i32 @naked_va(i32 %x, ...) #0 {
tail call void asm sideeffect inteldialect "mov eax, [esp + $$8]\0A\09ret", "~{eax},~{dirflag},~{fpsr},~{flags}"()
unreachable
}
define i32 @f(i32 %x, i32 %y) {
%r = call i32 @naked(i32 %x)
%s = call i32 (i32, ...) @naked_va(i32 %x, i32 %r)
; Make sure the arguments are still there: not removed or replaced with undef.
; CHECK: %r = call i32 @naked(i32 %x)
; CHECK: %s = call i32 (i32, ...) @naked_va(i32 %x, i32 %r)
ret i32 %s
}
attributes #0 = { naked }