Revert "Reland "[ARM] __cxa_end_cleanup should be called instead of _UnwindResume.""

This reverts commit b6420e5.

Author: DanielKristofKiss

libcxxabi/src/cxa_exception.cpp

@@ -341,10 +341,8 @@ unwinding with _Unwind_Resume.
 According to ARM EHABI 8.4.1, __cxa_end_cleanup() should not clobber any
 register, thus we have to write this function in assembly so that we can save
 {r1, r2, r3}.  We don't have to save r0 because it is the return value and the
-first argument to _Unwind_Resume().  In addition, we are saving lr in order to
-align the stack to 16 bytes and lr will be used to identify the caller and its
-frame information. _Unwind_Resume never return and we need to keep the original
-lr so just branch to it.
+first argument to _Unwind_Resume().  In addition, we are saving r4 in order to
+align the stack to 16 bytes, even though it is a callee-save register.
 */
 __attribute__((used)) static _Unwind_Exception *
 __cxa_end_cleanup_impl()
@@ -374,16 +372,18 @@ __cxa_end_cleanup_impl()
     return &exception_header->unwindHeader;
 }
 
-asm("	.pushsection	.text.__cxa_end_cleanup,\"ax\",%progbits\n"
+asm (
+    "	.pushsection	.text.__cxa_end_cleanup,\"ax\",%progbits\n"
     "	.globl	__cxa_end_cleanup\n"
     "	.type	__cxa_end_cleanup,%function\n"
     "__cxa_end_cleanup:\n"
-    "	push	{r1, r2, r3, lr}\n"
+    "	push	{r1, r2, r3, r4}\n"
     "	bl	__cxa_end_cleanup_impl\n"
     "	pop	{r1, r2, r3, r4}\n"
-    "	mov	lr, r4\n"
-    "	b	_Unwind_Resume\n"
-    "	.popsection");
+    "	bl	_Unwind_Resume\n"
+    "	bl	abort\n"
+    "	.popsection"
+);
 #endif // defined(_LIBCXXABI_ARM_EHABI)
 
 /*

llvm/include/llvm/ADT/Triple.h

@@ -721,19 +721,6 @@ class Triple {
     return getArch() == Triple::arm || getArch() == Triple::armeb;
   }
 
-  /// Tests whether the target supports the EHABI exception
-  /// handling standard.
-  bool isTargetEHABICompatible() const {
-    return isARM() &&
-           (getEnvironment() == Triple::EABI ||
-            getEnvironment() == Triple::GNUEABI ||
-            getEnvironment() == Triple::MuslEABI ||
-            getEnvironment() == Triple::EABIHF ||
-            getEnvironment() == Triple::GNUEABIHF ||
-            getEnvironment() == Triple::MuslEABIHF || isAndroid()) &&
-           isOSBinFormatELF();
-  }
-
   /// Tests whether the target is AArch64 (little and big endian).
   bool isAArch64() const {
     return getArch() == Triple::aarch64 || getArch() == Triple::aarch64_be ||

llvm/include/llvm/IR/RuntimeLibcalls.def

@@ -432,7 +432,6 @@ HANDLE_LIBCALL(MEMSET_ELEMENT_UNORDERED_ATOMIC_16, "__llvm_memset_element_unorde
 
 // Exception handling
 HANDLE_LIBCALL(UNWIND_RESUME, "_Unwind_Resume")
-HANDLE_LIBCALL(CXA_END_CLEANUP, "__cxa_end_cleanup")
 
 // Note: there are two sets of atomics libcalls; see
 // <https://llvm.org/docs/Atomics.html> for more info on the

llvm/lib/CodeGen/DwarfEHPrepare.cpp

@@ -14,7 +14,6 @@
 #include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/Triple.h"
 #include "llvm/Analysis/CFG.h"
 #include "llvm/Analysis/DomTreeUpdater.h"
 #include "llvm/Analysis/EHPersonalities.h"
@@ -55,11 +54,13 @@ namespace {
 class DwarfEHPrepare {
   CodeGenOpt::Level OptLevel;
 
+  // RewindFunction - _Unwind_Resume or the target equivalent.
+  FunctionCallee &RewindFunction;
+
   Function &F;
   const TargetLowering &TLI;
   DomTreeUpdater *DTU;
   const TargetTransformInfo *TTI;
-  const Triple &TargetTriple;
 
   /// Return the exception object from the value passed into
   /// the 'resume' instruction (typically an aggregate). Clean up any dead
@@ -77,11 +78,11 @@ class DwarfEHPrepare {
   bool InsertUnwindResumeCalls();
 
 public:
-  DwarfEHPrepare(CodeGenOpt::Level OptLevel_, Function &F_,
-                 const TargetLowering &TLI_, DomTreeUpdater *DTU_,
-                 const TargetTransformInfo *TTI_, const Triple &TargetTriple_)
-      : OptLevel(OptLevel_), F(F_), TLI(TLI_), DTU(DTU_), TTI(TTI_),
-        TargetTriple(TargetTriple_) {}
+  DwarfEHPrepare(CodeGenOpt::Level OptLevel_, FunctionCallee &RewindFunction_,
+                 Function &F_, const TargetLowering &TLI_, DomTreeUpdater *DTU_,
+                 const TargetTransformInfo *TTI_)
+      : OptLevel(OptLevel_), RewindFunction(RewindFunction_), F(F_), TLI(TLI_),
+        DTU(DTU_), TTI(TTI_) {}
 
   bool run();
 };
@@ -210,28 +211,13 @@ bool DwarfEHPrepare::InsertUnwindResumeCalls() {
   if (ResumesLeft == 0)
     return true; // We pruned them all.
 
-  // RewindFunction - _Unwind_Resume or the target equivalent.
-  FunctionCallee RewindFunction;
-  CallingConv::ID RewindFunctionCallingConv;
-  FunctionType *FTy;
-  const char *RewindName;
-  bool DoesRewindFunctionNeedExceptionObject;
-
-  if ((Pers == EHPersonality::GNU_CXX || Pers == EHPersonality::GNU_CXX_SjLj) &&
-      TargetTriple.isTargetEHABICompatible()) {
-    RewindName = TLI.getLibcallName(RTLIB::CXA_END_CLEANUP);
-    FTy = FunctionType::get(Type::getVoidTy(Ctx), false);
-    RewindFunctionCallingConv =
-        TLI.getLibcallCallingConv(RTLIB::CXA_END_CLEANUP);
-    DoesRewindFunctionNeedExceptionObject = false;
-  } else {
-    RewindName = TLI.getLibcallName(RTLIB::UNWIND_RESUME);
-    FTy =
+  // Find the rewind function if we didn't already.
+  if (!RewindFunction) {
+    FunctionType *FTy =
         FunctionType::get(Type::getVoidTy(Ctx), Type::getInt8PtrTy(Ctx), false);
-    RewindFunctionCallingConv = TLI.getLibcallCallingConv(RTLIB::UNWIND_RESUME);
-    DoesRewindFunctionNeedExceptionObject = true;
+    const char *RewindName = TLI.getLibcallName(RTLIB::UNWIND_RESUME);
+    RewindFunction = F.getParent()->getOrInsertFunction(RewindName, FTy);
   }
-  RewindFunction = F.getParent()->getOrInsertFunction(RewindName, FTy);
 
   // Create the basic block where the _Unwind_Resume call will live.
   if (ResumesLeft == 1) {
@@ -240,14 +226,10 @@ bool DwarfEHPrepare::InsertUnwindResumeCalls() {
     ResumeInst *RI = Resumes.front();
     BasicBlock *UnwindBB = RI->getParent();
     Value *ExnObj = GetExceptionObject(RI);
-    llvm::SmallVector<Value *, 1> RewindFunctionArgs;
-    if (DoesRewindFunctionNeedExceptionObject)
-      RewindFunctionArgs.push_back(ExnObj);
 
-    // Call the rewind function.
-    CallInst *CI =
-        CallInst::Create(RewindFunction, RewindFunctionArgs, "", UnwindBB);
-    CI->setCallingConv(RewindFunctionCallingConv);
+    // Call the _Unwind_Resume function.
+    CallInst *CI = CallInst::Create(RewindFunction, ExnObj, "", UnwindBB);
+    CI->setCallingConv(TLI.getLibcallCallingConv(RTLIB::UNWIND_RESUME));
 
     // We never expect _Unwind_Resume to return.
     CI->setDoesNotReturn();
@@ -258,8 +240,6 @@ bool DwarfEHPrepare::InsertUnwindResumeCalls() {
   std::vector<DominatorTree::UpdateType> Updates;
   Updates.reserve(Resumes.size());
 
-  llvm::SmallVector<Value *, 1> RewindFunctionArgs;
-
   BasicBlock *UnwindBB = BasicBlock::Create(Ctx, "unwind_resume", &F);
   PHINode *PN = PHINode::Create(Type::getInt8PtrTy(Ctx), ResumesLeft, "exn.obj",
                                 UnwindBB);
@@ -277,13 +257,9 @@ bool DwarfEHPrepare::InsertUnwindResumeCalls() {
     ++NumResumesLowered;
   }
 
-  if (DoesRewindFunctionNeedExceptionObject)
-    RewindFunctionArgs.push_back(PN);
-
   // Call the function.
-  CallInst *CI =
-      CallInst::Create(RewindFunction, RewindFunctionArgs, "", UnwindBB);
-  CI->setCallingConv(RewindFunctionCallingConv);
+  CallInst *CI = CallInst::Create(RewindFunction, PN, "", UnwindBB);
+  CI->setCallingConv(TLI.getLibcallCallingConv(RTLIB::UNWIND_RESUME));
 
   // We never expect _Unwind_Resume to return.
   CI->setDoesNotReturn();
@@ -301,20 +277,22 @@ bool DwarfEHPrepare::run() {
   return Changed;
 }
 
-static bool prepareDwarfEH(CodeGenOpt::Level OptLevel, Function &F,
+static bool prepareDwarfEH(CodeGenOpt::Level OptLevel,
+                           FunctionCallee &RewindFunction, Function &F,
                            const TargetLowering &TLI, DominatorTree *DT,
-                           const TargetTransformInfo *TTI,
-                           const Triple &TargetTriple) {
+                           const TargetTransformInfo *TTI) {
   DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy);
 
-  return DwarfEHPrepare(OptLevel, F, TLI, DT ? &DTU : nullptr, TTI,
-                        TargetTriple)
+  return DwarfEHPrepare(OptLevel, RewindFunction, F, TLI, DT ? &DTU : nullptr,
+                        TTI)
       .run();
 }
 
 namespace {
 
 class DwarfEHPrepareLegacyPass : public FunctionPass {
+  // RewindFunction - _Unwind_Resume or the target equivalent.
+  FunctionCallee RewindFunction = nullptr;
 
   CodeGenOpt::Level OptLevel;
 
@@ -337,7 +315,12 @@ class DwarfEHPrepareLegacyPass : public FunctionPass {
         DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
       TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
     }
-    return prepareDwarfEH(OptLevel, F, TLI, DT, TTI, TM.getTargetTriple());
+    return prepareDwarfEH(OptLevel, RewindFunction, F, TLI, DT, TTI);
+  }
+
+  bool doFinalization(Module &M) override {
+    RewindFunction = nullptr;
+    return false;
   }
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {

llvm/lib/Target/ARM/ARMSubtarget.h

@@ -792,7 +792,14 @@ class ARMSubtarget : public ARMGenSubtargetInfo {
   // ARM Targets that support EHABI exception handling standard
   // Darwin uses SjLj. Other targets might need more checks.
   bool isTargetEHABICompatible() const {
-    return TargetTriple.isTargetEHABICompatible();
+    return (TargetTriple.getEnvironment() == Triple::EABI ||
+            TargetTriple.getEnvironment() == Triple::GNUEABI ||
+            TargetTriple.getEnvironment() == Triple::MuslEABI ||
+            TargetTriple.getEnvironment() == Triple::EABIHF ||
+            TargetTriple.getEnvironment() == Triple::GNUEABIHF ||
+            TargetTriple.getEnvironment() == Triple::MuslEABIHF ||
+            isTargetAndroid()) &&
+           !isTargetDarwin() && !isTargetWindows();
   }
 
   bool isTargetHardFloat() const;

llvm/test/CodeGen/ARM/debug-frame.ll

@@ -197,27 +197,29 @@ declare void @_ZSt9terminatev()
 
 ; CHECK-V7-FP-LABEL: _Z4testiiiiiddddd:
 ; CHECK-V7-FP:   .cfi_startproc
-; CHECK-V7-FP:   push   {r11, lr}
-; CHECK-V7-FP:   .cfi_def_cfa_offset 8
+; CHECK-V7-FP:   push   {r4, r10, r11, lr}
+; CHECK-V7-FP:   .cfi_def_cfa_offset 16
 ; CHECK-V7-FP:   .cfi_offset lr, -4
 ; CHECK-V7-FP:   .cfi_offset r11, -8
-; CHECK-V7-FP:   mov     r11, sp
-; CHECK-V7-FP:   .cfi_def_cfa_register r11
+; CHECK-V7-FP:   .cfi_offset r10, -12
+; CHECK-V7-FP:   .cfi_offset r4, -16
+; CHECK-V7-FP:   add    r11, sp, #8
+; CHECK-V7-FP:   .cfi_def_cfa r11, 8
 ; CHECK-V7-FP:   vpush  {d8, d9, d10, d11, d12}
-; CHECK-V7-FP:   .cfi_offset d12, -16
-; CHECK-V7-FP:   .cfi_offset d11, -24
-; CHECK-V7-FP:   .cfi_offset d10, -32
-; CHECK-V7-FP:   .cfi_offset d9, -40
-; CHECK-V7-FP:   .cfi_offset d8, -48
+; CHECK-V7-FP:   .cfi_offset d12, -24
+; CHECK-V7-FP:   .cfi_offset d11, -32
+; CHECK-V7-FP:   .cfi_offset d10, -40
+; CHECK-V7-FP:   .cfi_offset d9, -48
+; CHECK-V7-FP:   .cfi_offset d8, -56
 ; CHECK-V7-FP:   sub    sp, sp, #24
 ; CHECK-V7-FP:   .cfi_endproc
 
 ; CHECK-V7-FP-ELIM-LABEL: _Z4testiiiiiddddd:
 ; CHECK-V7-FP-ELIM:   .cfi_startproc
-; CHECK-V7-FP-ELIM:   push   {r11, lr}
+; CHECK-V7-FP-ELIM:   push   {r4, lr}
 ; CHECK-V7-FP-ELIM:   .cfi_def_cfa_offset 8
 ; CHECK-V7-FP-ELIM:   .cfi_offset lr, -4
-; CHECK-V7-FP-ELIM:   .cfi_offset r11, -8
+; CHECK-V7-FP-ELIM:   .cfi_offset r4, -8
 ; CHECK-V7-FP-ELIM:   vpush  {d8, d9, d10, d11, d12}
 ; CHECK-V7-FP-ELIM:   .cfi_def_cfa_offset 48
 ; CHECK-V7-FP-ELIM:   .cfi_offset d12, -16
@@ -258,27 +260,29 @@ declare void @_ZSt9terminatev()
 
 ; CHECK-THUMB-V7-FP-LABEL: _Z4testiiiiiddddd:
 ; CHECK-THUMB-V7-FP:   .cfi_startproc
-; CHECK-THUMB-V7-FP:   push   {r7, lr}
-; CHECK-THUMB-V7-FP:   .cfi_def_cfa_offset 8
+; CHECK-THUMB-V7-FP:   push   {r4, r6, r7, lr}
+; CHECK-THUMB-V7-FP:   .cfi_def_cfa_offset 16
 ; CHECK-THUMB-V7-FP:   .cfi_offset lr, -4
 ; CHECK-THUMB-V7-FP:   .cfi_offset r7, -8
-; CHECK-THUMB-V7-FP:   mov    r7, sp
-; CHECK-THUMB-V7-FP:   .cfi_def_cfa_register r7
+; CHECK-THUMB-V7-FP:   .cfi_offset r6, -12
+; CHECK-THUMB-V7-FP:   .cfi_offset r4, -16
+; CHECK-THUMB-V7-FP:   add    r7, sp, #8
+; CHECK-THUMB-V7-FP:   .cfi_def_cfa r7, 8
 ; CHECK-THUMB-V7-FP:   vpush  {d8, d9, d10, d11, d12}
-; CHECK-THUMB-V7-FP:   .cfi_offset d12, -16
-; CHECK-THUMB-V7-FP:   .cfi_offset d11, -24
-; CHECK-THUMB-V7-FP:   .cfi_offset d10, -32
-; CHECK-THUMB-V7-FP:   .cfi_offset d9, -40
-; CHECK-THUMB-V7-FP:   .cfi_offset d8, -48
+; CHECK-THUMB-V7-FP:   .cfi_offset d12, -24
+; CHECK-THUMB-V7-FP:   .cfi_offset d11, -32
+; CHECK-THUMB-V7-FP:   .cfi_offset d10, -40
+; CHECK-THUMB-V7-FP:   .cfi_offset d9, -48
+; CHECK-THUMB-V7-FP:   .cfi_offset d8, -56
 ; CHECK-THUMB-V7-FP:   sub    sp, #24
 ; CHECK-THUMB-V7-FP:   .cfi_endproc
 
 ; CHECK-THUMB-V7-FP-ELIM-LABEL: _Z4testiiiiiddddd:
 ; CHECK-THUMB-V7-FP-ELIM:   .cfi_startproc
-; CHECK-THUMB-V7-FP-ELIM:   push   {r7, lr}
+; CHECK-THUMB-V7-FP-ELIM:   push   {r4, lr}
 ; CHECK-THUMB-V7-FP-ELIM:   .cfi_def_cfa_offset 8
 ; CHECK-THUMB-V7-FP-ELIM:   .cfi_offset lr, -4
-; CHECK-THUMB-V7-FP-ELIM:   .cfi_offset r7, -8
+; CHECK-THUMB-V7-FP-ELIM:   .cfi_offset r4, -8
 ; CHECK-THUMB-V7-FP-ELIM:   vpush  {d8, d9, d10, d11, d12}
 ; CHECK-THUMB-V7-FP-ELIM:   .cfi_def_cfa_offset 48
 ; CHECK-THUMB-V7-FP-ELIM:   .cfi_offset d12, -16
@@ -292,18 +296,20 @@ declare void @_ZSt9terminatev()
 
 ; CHECK-THUMB-V7-FP-NOIAS-LABEL: _Z4testiiiiiddddd:
 ; CHECK-THUMB-V7-FP-NOIAS:   .cfi_startproc
-; CHECK-THUMB-V7-FP-NOIAS:   push   {r7, lr}
-; CHECK-THUMB-V7-FP-NOIAS:   .cfi_def_cfa_offset 8
+; CHECK-THUMB-V7-FP-NOIAS:   push   {r4, r6, r7, lr}
+; CHECK-THUMB-V7-FP-NOIAS:   .cfi_def_cfa_offset 16
 ; CHECK-THUMB-V7-FP-NOIAS:   .cfi_offset 14, -4
 ; CHECK-THUMB-V7-FP-NOIAS:   .cfi_offset 7, -8
-; CHECK-THUMB-V7-FP-NOIAS:   mov    r7, sp
-; CHECK-THUMB-V7-FP-NOIAS:   .cfi_def_cfa_register 7
+; CHECK-THUMB-V7-FP-NOIAS:   .cfi_offset 6, -12
+; CHECK-THUMB-V7-FP-NOIAS:   .cfi_offset 4, -16
+; CHECK-THUMB-V7-FP-NOIAS:   add    r7, sp, #8
+; CHECK-THUMB-V7-FP-NOIAS:   .cfi_def_cfa 7, 8
 ; CHECK-THUMB-V7-FP-NOIAS:   vpush  {d8, d9, d10, d11, d12}
-; CHECK-THUMB-V7-FP-NOIAS:   .cfi_offset 268, -16
-; CHECK-THUMB-V7-FP-NOIAS:   .cfi_offset 267, -24
-; CHECK-THUMB-V7-FP-NOIAS:   .cfi_offset 266, -32
-; CHECK-THUMB-V7-FP-NOIAS:   .cfi_offset 265, -40
-; CHECK-THUMB-V7-FP-NOIAS:   .cfi_offset 264, -48
+; CHECK-THUMB-V7-FP-NOIAS:   .cfi_offset 268, -24
+; CHECK-THUMB-V7-FP-NOIAS:   .cfi_offset 267, -32
+; CHECK-THUMB-V7-FP-NOIAS:   .cfi_offset 266, -40
+; CHECK-THUMB-V7-FP-NOIAS:   .cfi_offset 265, -48
+; CHECK-THUMB-V7-FP-NOIAS:   .cfi_offset 264, -56
 ; CHECK-THUMB-V7-FP-NOIAS:   sub    sp, #24
 ; CHECK-THUMB-V7-FP-NOIAS:   .cfi_endproc
 

llvm/test/CodeGen/ARM/eh-resume.ll llvm/test/CodeGen/ARM/eh-resume-darwin.ll

@@ -2,8 +2,6 @@
 ; RUN: llc < %s -mtriple=armv7-apple-watchos -arm-atomic-cfg-tidy=0 | FileCheck %s -check-prefix=IOS
 ; RUN: llc < %s -mtriple=armv7k-apple-ios -arm-atomic-cfg-tidy=0 | FileCheck %s -check-prefix=WATCHABI
 ; RUN: llc < %s -mtriple=armv7k-apple-watchos -arm-atomic-cfg-tidy=0 | FileCheck %s -check-prefix=WATCHABI
-; RUN: llc < %s -mtriple=armv7-none-gnueabihf -arm-atomic-cfg-tidy=0 | FileCheck %s -check-prefix=EABI
-; RUN: llc < %s -mtriple=armv7-none-none -arm-atomic-cfg-tidy=0 | FileCheck %s -check-prefix=ABI
 
 declare void @func()
 
@@ -25,5 +23,3 @@ lpad:
 
 ; IOS: __Unwind_SjLj_Resume
 ; WATCHABI: __Unwind_Resume
-; EABI: __cxa_end_cleanup
-; ABI: _Unwind_Resume