[llvm] r306145 - Revert "[Hexagon] Handle decreasing of stack alignment in frame lowering"
Krzysztof Parzyszek via llvm-commits
llvm-commits at lists.llvm.org
Fri Jun 23 12:47:04 PDT 2017
Author: kparzysz
Date: Fri Jun 23 14:47:04 2017
New Revision: 306145
URL: http://llvm.org/viewvc/llvm-project?rev=306145&view=rev
Log:
Revert "[Hexagon] Handle decreasing of stack alignment in frame lowering"
This breaks passing of aligned function arguments.
Removed:
llvm/trunk/test/CodeGen/Hexagon/stack-align-reset.ll
Modified:
llvm/trunk/lib/Target/Hexagon/HexagonFrameLowering.cpp
llvm/trunk/lib/Target/Hexagon/HexagonFrameLowering.h
llvm/trunk/lib/Target/Hexagon/HexagonRegisterInfo.cpp
llvm/trunk/lib/Target/Hexagon/HexagonRegisterInfo.h
Modified: llvm/trunk/lib/Target/Hexagon/HexagonFrameLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Hexagon/HexagonFrameLowering.cpp?rev=306145&r1=306144&r2=306145&view=diff
==============================================================================
--- llvm/trunk/lib/Target/Hexagon/HexagonFrameLowering.cpp (original)
+++ llvm/trunk/lib/Target/Hexagon/HexagonFrameLowering.cpp Fri Jun 23 14:47:04 2017
@@ -552,7 +552,7 @@ void HexagonFrameLowering::insertPrologu
auto &HRI = *HST.getRegisterInfo();
DebugLoc dl;
- unsigned MaxAlign = std::max(getMaxStackAlignment(MF), getStackAlignment());
+ unsigned MaxAlign = std::max(MFI.getMaxAlignment(), getStackAlignment());
// Calculate the total stack frame size.
// Get the number of bytes to allocate from the FrameInfo.
@@ -2354,26 +2354,11 @@ void HexagonFrameLowering::expandAlloca(
}
}
-unsigned
-HexagonFrameLowering::getMaxStackAlignment(const MachineFunction &MF) const {
- const MachineFrameInfo &MFI = MF.getFrameInfo();
- // MFI's MaxAlignment can only grow, but we can actually reduce it
- // for vector spills.
- unsigned MaxAlign = 0;
- for (int i = 0, e = MFI.getObjectIndexEnd(); i != e; ++i) {
- if (MFI.isDeadObjectIndex(i))
- continue;
- unsigned Align = MFI.getObjectAlignment(i);
- MaxAlign = std::max(MaxAlign, Align);
- }
- return MaxAlign;
-}
-
bool HexagonFrameLowering::needsAligna(const MachineFunction &MF) const {
const MachineFrameInfo &MFI = MF.getFrameInfo();
if (!MFI.hasVarSizedObjects())
return false;
- unsigned MaxA = getMaxStackAlignment(MF);
+ unsigned MaxA = MFI.getMaxAlignment();
if (MaxA <= getStackAlignment())
return false;
return true;
Modified: llvm/trunk/lib/Target/Hexagon/HexagonFrameLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Hexagon/HexagonFrameLowering.h?rev=306145&r1=306144&r2=306145&view=diff
==============================================================================
--- llvm/trunk/lib/Target/Hexagon/HexagonFrameLowering.h (original)
+++ llvm/trunk/lib/Target/Hexagon/HexagonFrameLowering.h Fri Jun 23 14:47:04 2017
@@ -82,8 +82,6 @@ public:
const TargetRegisterInfo *TRI, std::vector<CalleeSavedInfo> &CSI)
const override;
- unsigned getMaxStackAlignment(const MachineFunction &MF) const;
-
bool needsAligna(const MachineFunction &MF) const;
const MachineInstr *getAlignaInstr(const MachineFunction &MF) const;
Modified: llvm/trunk/lib/Target/Hexagon/HexagonRegisterInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Hexagon/HexagonRegisterInfo.cpp?rev=306145&r1=306144&r2=306145&view=diff
==============================================================================
--- llvm/trunk/lib/Target/Hexagon/HexagonRegisterInfo.cpp (original)
+++ llvm/trunk/lib/Target/Hexagon/HexagonRegisterInfo.cpp Fri Jun 23 14:47:04 2017
@@ -283,36 +283,6 @@ bool HexagonRegisterInfo::useFPForScaven
return MF.getSubtarget<HexagonSubtarget>().getFrameLowering()->hasFP(MF);
}
-// The stack alignment on Hexagon can actually decrease in some cases,
-// specifically in some subset of cases when a variable-sized stack object
-// is present.
-// The issue is two-fold:
-// First of all, if there is a variable-sized object and the stack needs
-// extra alignment (due to pre-existing local objects), then a special
-// register will be reserved up front, acting as the aligned stack pointer
-// (call it AP). This register is only guaranteed to be live for accessing
-// these pre-existing local objects (the ones with the higher alignment).
-// Now, if the register allocator introduces vector register spills, their
-// spill slots will initially have an alignment equal to the register size,
-// which is higher than the normal stack alignment. Ideally, they should be
-// loaded/stored using AP, but AP may not be available at all required
-// places. To avoid this issue, the vector spill slots will have their
-// alignment lowered to 8, and they will be loaded/stored using unaligned
-// instructions.
-//
-// The lowering of the stack alignment may happen if the stack had a
-// variable-sized object, but otherwise retained its default alignment
-// up until register allocation. If the register allocator introduces
-// a vector spill, it will cause the max stack alignment to grow
-// (inside MachineFrameInfo). When the alignment of the spills is reset
-// back to the default stack alignment, MFI's max stack alignment will
-// not reflect that (since it cannot be lowered). Relying on that during
-// frame lowering will cause an unnecessary stack realignment.
-bool HexagonRegisterInfo::needsStackRealignment(const MachineFunction &MF)
- const {
- auto &HFI = *MF.getSubtarget<HexagonSubtarget>().getFrameLowering();
- return HFI.getMaxStackAlignment(MF) > HFI.getStackAlignment();
-}
unsigned HexagonRegisterInfo::getFirstCallerSavedNonParamReg() const {
return Hexagon::R6;
Modified: llvm/trunk/lib/Target/Hexagon/HexagonRegisterInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Hexagon/HexagonRegisterInfo.h?rev=306145&r1=306144&r2=306145&view=diff
==============================================================================
--- llvm/trunk/lib/Target/Hexagon/HexagonRegisterInfo.h (original)
+++ llvm/trunk/lib/Target/Hexagon/HexagonRegisterInfo.h Fri Jun 23 14:47:04 2017
@@ -55,8 +55,6 @@ public:
return true;
}
- bool needsStackRealignment(const MachineFunction &MF) const;
-
/// Returns true if the frame pointer is valid.
bool useFPForScavengingIndex(const MachineFunction &MF) const override;
Removed: llvm/trunk/test/CodeGen/Hexagon/stack-align-reset.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Hexagon/stack-align-reset.ll?rev=306144&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/Hexagon/stack-align-reset.ll (original)
+++ llvm/trunk/test/CodeGen/Hexagon/stack-align-reset.ll (removed)
@@ -1,51 +0,0 @@
-; RUN: llc -march=hexagon < %s | FileCheck %s
-;
-; This used to crash.
-; CHECK: call f1
-
-target triple = "hexagon-unknown--elf"
-
-%struct.0 = type { [5 x i32] }
-%struct.2 = type { i32, i32, i32, %struct.1* }
-%struct.1 = type { i16*, i32, i32, i32 }
-
- at g0 = external hidden unnamed_addr constant [52 x i8], align 1
- at g1 = external hidden unnamed_addr constant [3 x i8], align 1
-
-declare extern_weak void @f0(i32, i8*, i32, i8*, ...) #0
-declare void @f1(%struct.0*, i32) #0
-
-define void @fred(i8* %a0) #0 {
-b1:
- %v2 = alloca %struct.0, align 4
- %v3 = alloca %struct.2, i32 undef, align 8
- br i1 undef, label %b5, label %b4
-
-b4: ; preds = %b1
- br label %b7
-
-b5: ; preds = %b5, %b1
- %v6 = getelementptr inbounds %struct.2, %struct.2* %v3, i32 undef, i32 3
- store %struct.1* undef, %struct.1** %v6, align 4
- br label %b5
-
-b7: ; preds = %b10, %b4
- %v8 = call i32 @llvm.hexagon.V6.extractw(<16 x i32> zeroinitializer, i32 0)
- br i1 icmp eq (void (i32, i8*, i32, i8*, ...)* @f0, void (i32, i8*, i32, i8*, ...)* null), label %b11, label %b9
-
-b9: ; preds = %b7
- call void (i32, i8*, i32, i8*, ...) @f0(i32 2, i8* getelementptr inbounds ([52 x i8], [52 x i8]* @g0, i32 0, i32 0), i32 2346, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @g1, i32 0, i32 0), i32 %v8)
- unreachable
-
-b10: ; preds = %b11
- call void @f1(%struct.0* nonnull %v2, i32 28)
- br label %b7
-
-b11: ; preds = %b11, %b7
- br i1 undef, label %b10, label %b11
-}
-
-declare i32 @llvm.hexagon.V6.extractw(<16 x i32>, i32) #1
-
-attributes #0 = { nounwind "target-cpu"="hexagonv60" "target-features"="+hvx,-hvx-double" }
-attributes #1 = { nounwind readnone }
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