[clang] [llvm] [win][x64] Unwind v2 3/n: Add support for requiring unwind v2 to be used (equivalent to MSVC's /d2epilogunwindrequirev2) (PR #143577)

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``````````bash
git-clang-format --diff HEAD~1 HEAD --extensions c,cpp,h -- clang/lib/CodeGen/CodeGenModule.cpp clang/lib/Driver/ToolChains/Clang.cpp clang/test/CodeGen/epilog-unwind.c clang/test/Driver/cl-options.c llvm/include/llvm/IR/Module.h llvm/include/llvm/Support/CodeGen.h llvm/lib/IR/Module.cpp llvm/lib/Target/X86/X86WinEHUnwindV2.cpp
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View the diff from clang-format here.
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``````````diff
diff --git a/llvm/lib/Target/X86/X86WinEHUnwindV2.cpp b/llvm/lib/Target/X86/X86WinEHUnwindV2.cpp
index 01256ec89..ae53a5060 100644
--- a/llvm/lib/Target/X86/X86WinEHUnwindV2.cpp
+++ b/llvm/lib/Target/X86/X86WinEHUnwindV2.cpp
@@ -37,9 +37,9 @@ static cl::opt<unsigned> MaximumUnwindCodes(
     cl::desc("Maximum number of unwind codes permitted in each unwind info."),
     cl::init(UINT8_MAX));
 
-static cl::opt<unsigned> ForceMode(
-    "x86-wineh-unwindv2-force-mode", cl::Hidden,
-    cl::desc("Overwrites the Unwind v2 mode for testing purposes."));
+static cl::opt<unsigned>
+    ForceMode("x86-wineh-unwindv2-force-mode", cl::Hidden,
+              cl::desc("Overwrites the Unwind v2 mode for testing purposes."));
 
 namespace {
 
@@ -57,8 +57,7 @@ public:
 
 private:
   bool rejectCurrentFunction(const MachineFunction &MF, const DebugLoc &Loc,
-                             WinX64EHUnwindV2Mode Mode,
-                             StringRef Reason) const;
+                             WinX64EHUnwindV2Mode Mode, StringRef Reason) const;
 
   bool rejectCurrentFunction(const MachineFunction &MF,
                              const MachineBasicBlock &EpilogBlock,
@@ -67,8 +66,7 @@ private:
     // If we're in the Epilog, then the generated instructions might not have a
     // location, so use the terminator's location.
     return rejectCurrentFunction(
-        MF, EpilogBlock.getFirstTerminator()->getDebugLoc(), Mode,
-        Reason);
+        MF, EpilogBlock.getFirstTerminator()->getDebugLoc(), Mode, Reason);
   }
 };
 
@@ -204,14 +202,14 @@ bool X86WinEHUnwindV2::runOnMachineFunction(MachineFunction &MF) {
           // If the prolog contains a stack allocation, then the first
           // instruction in the epilog must be to adjust the stack pointer.
           if (!HasStackAlloc)
-            return rejectCurrentFunction(
-                MF, MBB, Mode,
-                "The epilog is deallocating a stack allocation, but the prolog did "
-                "not allocate one");
+            return rejectCurrentFunction(MF, MBB, Mode,
+                                         "The epilog is deallocating a stack "
+                                         "allocation, but the prolog did "
+                                         "not allocate one");
           if (HasStackDealloc)
-            return rejectCurrentFunction(
-                MF, MBB, Mode,
-                "The epilog is deallocating the stack allocation more than once");
+            return rejectCurrentFunction(MF, MBB, Mode,
+                                         "The epilog is deallocating the stack "
+                                         "allocation more than once");
           if (PoppedRegCount > 0)
             llvm_unreachable(
                 "Should have raised an error: either popping before "
@@ -230,19 +228,20 @@ bool X86WinEHUnwindV2::runOnMachineFunction(MachineFunction &MF) {
           // POP each register in reverse order of the PUSHes in the prolog.
           PoppedRegCount++;
           if (HasStackAlloc != HasStackDealloc)
-            return rejectCurrentFunction(MF, MBB, Mode,
-                                         "Cannot pop registers before the stack "
-                                         "allocation has been deallocated");
+            return rejectCurrentFunction(
+                MF, MBB, Mode,
+                "Cannot pop registers before the stack "
+                "allocation has been deallocated");
           if (PoppedRegCount > PushedRegs.size())
             return rejectCurrentFunction(
                 MF, MBB, Mode,
                 "The epilog is popping more registers than the prolog pushed");
           if (PushedRegs[PushedRegs.size() - PoppedRegCount] !=
               MI.getOperand(0).getReg())
-            return rejectCurrentFunction(
-                MF, MBB, Mode,
-                "The epilog is popping a registers in a different order than the "
-                "prolog pushed them");
+            return rejectCurrentFunction(MF, MBB, Mode,
+                                         "The epilog is popping a registers in "
+                                         "a different order than the "
+                                         "prolog pushed them");
 
           // Unwind v2 records the size of the epilog not from where we place
           // SEH_BeginEpilogue (as that contains the instruction to adjust the
@@ -255,8 +254,7 @@ bool X86WinEHUnwindV2::runOnMachineFunction(MachineFunction &MF) {
         } else if (State == FunctionState::FinishedEpilog)
           // Unexpected instruction after the epilog.
           return rejectCurrentFunction(
-              MF, MBB, Mode,
-              "Registers are being popped after the epilog");
+              MF, MBB, Mode, "Registers are being popped after the epilog");
         break;
 
       default:
@@ -291,9 +289,8 @@ bool X86WinEHUnwindV2::runOnMachineFunction(MachineFunction &MF) {
   // optimization.
   if (ApproximatePrologCodeCount + UnwindV2StartLocations.size() + 1 >
       static_cast<unsigned>(MaximumUnwindCodes))
-    return rejectCurrentFunction(
-        MF, findDebugLoc(FirstMBB), Mode,
-        "The function has too many epilogs");
+    return rejectCurrentFunction(MF, findDebugLoc(FirstMBB), Mode,
+                                 "The function has too many epilogs");
 
   MeetsUnwindV2Criteria++;
 

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https://github.com/llvm/llvm-project/pull/143577