diff options
| -rw-r--r-- | lib/Target/X86/X86RegisterInfo.cpp | 35 | ||||
| -rw-r--r-- | test/CodeGen/X86/force-align-stack.ll | 21 |
2 files changed, 55 insertions, 1 deletions
diff --git a/lib/Target/X86/X86RegisterInfo.cpp b/lib/Target/X86/X86RegisterInfo.cpp index 9acdc16815..746e3fa7b5 100644 --- a/lib/Target/X86/X86RegisterInfo.cpp +++ b/lib/Target/X86/X86RegisterInfo.cpp @@ -38,8 +38,15 @@ #include "llvm/ADT/BitVector.h" #include "llvm/ADT/STLExtras.h" #include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/CommandLine.h" using namespace llvm; +static cl::opt<bool> +ForceStackAlign("force-align-stack", + cl::desc("Force align the stack to the minimum alignment" + " needed for the function."), + cl::init(false), cl::Hidden); + X86RegisterInfo::X86RegisterInfo(X86TargetMachine &tm, const TargetInstrInfo &tii) : X86GenRegisterInfo(tm.getSubtarget<X86Subtarget>().is64Bit() ? @@ -471,7 +478,11 @@ bool X86RegisterInfo::needsStackRealignment(const MachineFunction &MF) const { if (0 && requiresRealignment && MFI->hasVarSizedObjects()) report_fatal_error( "Stack realignment in presense of dynamic allocas is not supported"); - + + // If we've requested that we force align the stack do so now. + if (ForceStackAlign) + return canRealignStack(MF); + return requiresRealignment && canRealignStack(MF); } @@ -906,6 +917,17 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const { bool HasFP = hasFP(MF); DebugLoc DL; + // If we're forcing a stack realignment we can't rely on just the frame + // info, we need to know the ABI stack alignment as well in case we + // have a call out. Otherwise just make sure we have some alignment - we'll + // go with the minimum SlotSize. + if (ForceStackAlign) { + if (MFI->hasCalls()) + MaxAlign = (StackAlign > MaxAlign) ? StackAlign : MaxAlign; + else if (MaxAlign < SlotSize) + MaxAlign = SlotSize; + } + // Add RETADDR move area to callee saved frame size. int TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta(); if (TailCallReturnAddrDelta < 0) @@ -1177,6 +1199,17 @@ void X86RegisterInfo::emitEpilogue(MachineFunction &MF, unsigned CSSize = X86FI->getCalleeSavedFrameSize(); uint64_t NumBytes = 0; + // If we're forcing a stack realignment we can't rely on just the frame + // info, we need to know the ABI stack alignment as well in case we + // have a call out. Otherwise just make sure we have some alignment - we'll + // go with the minimum. + if (ForceStackAlign) { + if (MFI->hasCalls()) + MaxAlign = (StackAlign > MaxAlign) ? StackAlign : MaxAlign; + else + MaxAlign = MaxAlign ? MaxAlign : 4; + } + if (hasFP(MF)) { // Calculate required stack adjustment. uint64_t FrameSize = StackSize - SlotSize; diff --git a/test/CodeGen/X86/force-align-stack.ll b/test/CodeGen/X86/force-align-stack.ll new file mode 100644 index 0000000000..ffcbf8a908 --- /dev/null +++ b/test/CodeGen/X86/force-align-stack.ll @@ -0,0 +1,21 @@ +; RUN: llc < %s -relocation-model=static -force-align-stack | FileCheck %s +; Tests to make sure that we always align the stack out to the minimum needed - +; in this case 16-bytes. +target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32" +target triple = "i386-apple-darwin10.3" + +define void @a() nounwind ssp { +entry: +; CHECK: _a: +; CHECK: andl $-16, %esp + %z = alloca <16 x i8> ; <<16 x i8>*> [#uses=2] + %"alloca point" = bitcast i32 0 to i32 ; <i32> [#uses=0] + store <16 x i8> zeroinitializer, <16 x i8>* %z, align 16 + call void @b(<16 x i8>* %z) nounwind + br label %return + +return: ; preds = %entry + ret void +} + +declare void @b(<16 x i8>*) |