[clang] [llvm] [BPF] introduce `__attribute__((bpf_fastcall))` (PR #101228)

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``````````bash
git-clang-format --diff 247251aee0d4314385a3fea86e31484d3d792ffb 02af8355ccdfb41199168a2b71c1b25a491a6310 --extensions c,h,cpp -- clang/test/CodeGen/bpf-attr-bpf-fastcall-1.c clang/test/Sema/bpf-attr-bpf-fastcall.c clang/lib/CodeGen/CGCall.cpp llvm/lib/Target/BPF/BPFISelLowering.cpp llvm/lib/Target/BPF/BPFMIPeephole.cpp llvm/lib/Target/BPF/BPFRegisterInfo.cpp llvm/lib/Target/BPF/BPFRegisterInfo.h
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View the diff from clang-format here.
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``````````diff
diff --git a/llvm/lib/Target/BPF/BPFISelLowering.cpp b/llvm/lib/Target/BPF/BPFISelLowering.cpp
index 3a72279976..ff23d3b055 100644
--- a/llvm/lib/Target/BPF/BPFISelLowering.cpp
+++ b/llvm/lib/Target/BPF/BPFISelLowering.cpp
@@ -403,7 +403,7 @@ SDValue BPFTargetLowering::LowerFormalArguments(
 const size_t BPFTargetLowering::MaxArgs = 5;
 
 static void resetRegMaskBit(const TargetRegisterInfo *TRI, uint32_t *RegMask,
-                          MCRegister Reg) {
+                            MCRegister Reg) {
   for (MCPhysReg SubReg : TRI->subregs_inclusive(Reg))
     RegMask[SubReg / 32] &= ~(1u << (SubReg % 32));
 }
@@ -528,8 +528,8 @@ SDValue BPFTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
   for (auto &Reg : RegsToPass)
     Ops.push_back(DAG.getRegister(Reg.first, Reg.second.getValueType()));
 
-  bool HasFastCall = (CLI.CB && isa<CallInst>(CLI.CB) &&
-                      CLI.CB->hasFnAttr("bpf_fastcall"));
+  bool HasFastCall =
+      (CLI.CB && isa<CallInst>(CLI.CB) && CLI.CB->hasFnAttr("bpf_fastcall"));
   const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
   if (HasFastCall) {
     uint32_t *RegMask = regMaskFromTemplate(
diff --git a/llvm/lib/Target/BPF/BPFMIPeephole.cpp b/llvm/lib/Target/BPF/BPFMIPeephole.cpp
index 5ee0893946..5ada86a8bf 100644
--- a/llvm/lib/Target/BPF/BPFMIPeephole.cpp
+++ b/llvm/lib/Target/BPF/BPFMIPeephole.cpp
@@ -25,10 +25,10 @@
 #include "BPFTargetMachine.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/CodeGen/LivePhysRegs.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/Support/Debug.h"
 #include <set>
 
@@ -600,8 +600,8 @@ bool BPFMIPreEmitPeephole::adjustBranch() {
   return Changed;
 }
 
-static const unsigned CallerSavedRegs[] =
-  {BPF::R0, BPF::R1, BPF::R2, BPF::R3, BPF::R4, BPF::R5};
+static const unsigned CallerSavedRegs[] = {BPF::R0, BPF::R1, BPF::R2,
+                                           BPF::R3, BPF::R4, BPF::R5};
 
 struct BPFFastCall {
   MachineInstr *MI;
@@ -609,31 +609,31 @@ struct BPFFastCall {
 };
 
 static void collectBPFFastCalls(const TargetRegisterInfo *TRI,
-                                LivePhysRegs &LiveRegs,
-                                MachineBasicBlock &BB,
+                                LivePhysRegs &LiveRegs, MachineBasicBlock &BB,
                                 SmallVectorImpl<BPFFastCall> &Calls) {
-    LiveRegs.init(*TRI);
-    LiveRegs.addLiveOuts(BB);
-    Calls.clear();
-    for (MachineInstr &MI: llvm::reverse(BB)) {
-      unsigned LiveCallerSavedRegs;
-      if (!MI.isCall())
-        goto NextInsn;
-      LiveCallerSavedRegs = 0;
-      for (MCRegister R: CallerSavedRegs) {
-        bool DoSpillFill = !MI.definesRegister(R, TRI) && LiveRegs.contains(R);
-        if (!DoSpillFill)
-          continue;
-        LiveCallerSavedRegs |= 1 << R;
-      }
-      if (LiveCallerSavedRegs)
-        Calls.push_back({&MI, LiveCallerSavedRegs});
-    NextInsn:
-      LiveRegs.stepBackward(MI);
+  LiveRegs.init(*TRI);
+  LiveRegs.addLiveOuts(BB);
+  Calls.clear();
+  for (MachineInstr &MI : llvm::reverse(BB)) {
+    unsigned LiveCallerSavedRegs;
+    if (!MI.isCall())
+      goto NextInsn;
+    LiveCallerSavedRegs = 0;
+    for (MCRegister R : CallerSavedRegs) {
+      bool DoSpillFill = !MI.definesRegister(R, TRI) && LiveRegs.contains(R);
+      if (!DoSpillFill)
+        continue;
+      LiveCallerSavedRegs |= 1 << R;
     }
+    if (LiveCallerSavedRegs)
+      Calls.push_back({&MI, LiveCallerSavedRegs});
+  NextInsn:
+    LiveRegs.stepBackward(MI);
+  }
 }
 
-static int64_t computeMinFixedObjOffset(MachineFrameInfo &MFI, unsigned SlotSize) {
+static int64_t computeMinFixedObjOffset(MachineFrameInfo &MFI,
+                                        unsigned SlotSize) {
   int64_t MinFixedObjOffset = 0;
   // Same logic as in X86FrameLowering::adjustFrameForMsvcCxxEh()
   for (int I = MFI.getObjectIndexBegin(); I < MFI.getObjectIndexEnd(); ++I) {
@@ -641,7 +641,8 @@ static int64_t computeMinFixedObjOffset(MachineFrameInfo &MFI, unsigned SlotSize
       continue;
     MinFixedObjOffset = std::min(MinFixedObjOffset, MFI.getObjectOffset(I));
   }
-  MinFixedObjOffset -= (SlotSize + MinFixedObjOffset % SlotSize) & (SlotSize - 1);
+  MinFixedObjOffset -=
+      (SlotSize + MinFixedObjOffset % SlotSize) & (SlotSize - 1);
   return MinFixedObjOffset;
 }
 
@@ -652,29 +653,31 @@ bool BPFMIPreEmitPeephole::insertMissingCallerSavedSpills() {
   const unsigned SlotSize = 8;
   int64_t MinFixedObjOffset = computeMinFixedObjOffset(MFI, SlotSize);
   bool Changed = false;
-  for (MachineBasicBlock &BB: *MF) {
+  for (MachineBasicBlock &BB : *MF) {
     collectBPFFastCalls(TRI, LiveRegs, BB, Calls);
     Changed |= !Calls.empty();
-    for (BPFFastCall &Call: Calls) {
+    for (BPFFastCall &Call : Calls) {
       int64_t CurOffset = MinFixedObjOffset;
-      for (MCRegister Reg: CallerSavedRegs) {
+      for (MCRegister Reg : CallerSavedRegs) {
         if (((1 << Reg) & Call.LiveCallerSavedRegs) == 0)
           continue;
         // Allocate stack object
         CurOffset -= SlotSize;
         MFI.CreateFixedSpillStackObject(SlotSize, CurOffset);
         // Generate spill
-        BuildMI(BB, Call.MI->getIterator(), Call.MI->getDebugLoc(), TII->get(BPF::STD))
-          .addReg(Reg)
-          .addReg(BPF::R10)
-          .addImm(CurOffset)
-          .addImm(0);
+        BuildMI(BB, Call.MI->getIterator(), Call.MI->getDebugLoc(),
+                TII->get(BPF::STD))
+            .addReg(Reg)
+            .addReg(BPF::R10)
+            .addImm(CurOffset)
+            .addImm(0);
         // Generate fill
-        BuildMI(BB, ++Call.MI->getIterator(), Call.MI->getDebugLoc(), TII->get(BPF::LDD))
-          .addReg(Reg)
-          .addReg(BPF::R10)
-          .addImm(CurOffset)
-          .addImm(0);
+        BuildMI(BB, ++Call.MI->getIterator(), Call.MI->getDebugLoc(),
+                TII->get(BPF::LDD))
+            .addReg(Reg)
+            .addReg(BPF::R10)
+            .addImm(CurOffset)
+            .addImm(0);
       }
     }
   }

``````````

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https://github.com/llvm/llvm-project/pull/101228