diff options
3 files changed, 51 insertions, 12 deletions
diff --git a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp index 48c0916c74c..d7399e7f4f4 100644 --- a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp +++ b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp @@ -1032,20 +1032,36 @@ int AArch64FrameLowering::resolveFrameIndexReference(const MachineFunction &MF, // Argument access should always use the FP. if (isFixed) { UseFP = hasFP(MF); - } else if (hasFP(MF) && !RegInfo->hasBasePointer(MF) && - !RegInfo->needsStackRealignment(MF)) { - // Use SP or FP, whichever gives us the best chance of the offset - // being in range for direct access. If the FPOffset is positive, - // that'll always be best, as the SP will be even further away. + } else if (hasFP(MF) && !RegInfo->needsStackRealignment(MF)) { // If the FPOffset is negative, we have to keep in mind that the // available offset range for negative offsets is smaller than for - // positive ones. If we have variable sized objects, we're stuck with - // using the FP regardless, though, as the SP offset is unknown - // and we don't have a base pointer available. If an offset is + // positive ones. If an offset is // available via the FP and the SP, use whichever is closest. - if (PreferFP || MFI.hasVarSizedObjects() || FPOffset >= 0 || - (FPOffset >= -256 && Offset > -FPOffset)) + bool FPOffsetFits = FPOffset >= -256; + PreferFP |= Offset > -FPOffset; + + if (MFI.hasVarSizedObjects()) { + // If we have variable sized objects, we can use either FP or BP, as the + // SP offset is unknown. We can use the base pointer if we have one and + // FP is not preferred. If not, we're stuck with using FP. + bool CanUseBP = RegInfo->hasBasePointer(MF); + if (FPOffsetFits && CanUseBP) // Both are ok. Pick the best. + UseFP = PreferFP; + else if (!CanUseBP) // Can't use BP. Forced to use FP. + UseFP = true; + // else we can use BP and FP, but the offset from FP won't fit. + // That will make us scavenge registers which we can probably avoid by + // using BP. If it won't fit for BP either, we'll scavenge anyway. + } else if (PreferFP || FPOffset >= 0) { + // Use SP or FP, whichever gives us the best chance of the offset + // being in range for direct access. If the FPOffset is positive, + // that'll always be best, as the SP will be even further away. UseFP = true; + } else { + // We have the choice between FP and (SP or BP). + if (FPOffsetFits && PreferFP) // If FP is the best fit, use it. + UseFP = true; + } } } @@ -1062,6 +1078,8 @@ int AArch64FrameLowering::resolveFrameIndexReference(const MachineFunction &MF, if (RegInfo->hasBasePointer(MF)) FrameReg = RegInfo->getBaseRegister(); else { + assert(!MFI.hasVarSizedObjects() && + "Can't use SP when we have var sized objects."); FrameReg = AArch64::SP; // If we're using the red zone for this function, the SP won't actually // be adjusted, so the offsets will be negative. They're also all diff --git a/llvm/test/CodeGen/AArch64/arm64-alloca-frame-pointer-offset.ll b/llvm/test/CodeGen/AArch64/arm64-alloca-frame-pointer-offset.ll index fdb37987104..45e32c8aa63 100644 --- a/llvm/test/CodeGen/AArch64/arm64-alloca-frame-pointer-offset.ll +++ b/llvm/test/CodeGen/AArch64/arm64-alloca-frame-pointer-offset.ll @@ -1,8 +1,8 @@ ; RUN: llc -mtriple=arm64-eabi -mcpu=cyclone < %s | FileCheck %s ; CHECK: foo -; CHECK-DAG: str w[[REG0:[0-9]+]], [x19, #132] -; CHECK-DAG: str w[[REG0]], [x19, #264] +; CHECK-DAG: stur w[[REG0:[0-9]+]], [x29, #-24] +; CHECK-DAG: stur w[[REG0]], [x29, #-20] define i32 @foo(i32 %a) nounwind { %retval = alloca i32, align 4 %a.addr = alloca i32, align 4 diff --git a/llvm/test/CodeGen/AArch64/unreachable-emergency-spill-slot.mir b/llvm/test/CodeGen/AArch64/unreachable-emergency-spill-slot.mir new file mode 100644 index 00000000000..686fbe88911 --- /dev/null +++ b/llvm/test/CodeGen/AArch64/unreachable-emergency-spill-slot.mir @@ -0,0 +1,21 @@ +#RUN: llc -mtriple=aarch64-- -run-pass prologepilog %s -o - | FileCheck %s +# Check that we use the frame pointer to address the emergency spill slot. +# Using the base pointer will result in an assert with "Emergency spill slot is +# out of reach". +--- +name: hugeStack +# CHECK-LABEL: name: hugeStack +tracksRegLiveness: true +frameInfo: + localFrameSize: 256 +stack: + - { id: 0, type: variable-sized, alignment: 1 } + - { id: 1, name: '', size: 32761, alignment: 8 } +body: | + bb.0: + STRXui undef $x8, %stack.0, 0 + ; CHECK: STURXi undef $x8, $fp, -24 + B %bb.1 + bb.1: + liveins: $x0, $x1, $x2, $x3, $x4, $x5, $x6, $x7, $x8, $x9, $x10, $x11, $x12, $x13, $x14, $x15, $x16, $x17, $x18, $x19, $x20, $x21, $x22, $x23, $x24, $x25, $x26, $x27, $x28, $fp, $lr + RET_ReallyLR implicit $x21, implicit $x22, implicit $x23, implicit $x24, implicit $x25, implicit $x26, implicit $x27, implicit $x28 |
