[XCOFF] Handle the case when personality routine is an alias

[jasonliu]

Summary

Personality routine could be an alias to another personality routine.
Fix the situation when we compile the file that contains the personality routine and the file also have functions that need to refer to the personality routine.

[hubert.reinterpretcast]

llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp

2147–2149

Why remove the const?

[hubert.reinterpretcast]

llvm/test/CodeGen/PowerPC/aix-personality-alias.ll

49–56

Nit: Can we try to keep the alignment? Same below.

[jasonliu]

Address comments.

[hubert.reinterpretcast]

LGTM; thanks!

llvm/lib/Analysis/EHPersonalities.cpp

 #include "llvm/IR/Instructions.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 /// See if the given exception handling personality function is one that we
 /// understand.  If so, return a description of it; otherwise return Unknown.
 EHPersonality llvm::classifyEHPersonality(const Value *Pers) {
-  const Function *F =
-      Pers ? dyn_cast<Function>(Pers->stripPointerCasts()) : nullptr;
-  if (!F)
+  const GlobalValue *F =
+      Pers ? dyn_cast<GlobalValue>(Pers->stripPointerCasts()) : nullptr;
+  if (!F || !F->getValueType() || !F->getValueType()->isFunctionTy())
     return EHPersonality::Unknown;
   return StringSwitch<EHPersonality>(F->getName())
       .Case("__gnat_eh_personality", EHPersonality::GNU_Ada)
       .Case("__gxx_personality_v0", EHPersonality::GNU_CXX)
       .Case("__gxx_personality_seh0", EHPersonality::GNU_CXX)
       .Case("__gxx_personality_sj0", EHPersonality::GNU_CXX_SjLj)
       .Case("__gcc_personality_v0", EHPersonality::GNU_C)
       .Case("__gcc_personality_seh0", EHPersonality::GNU_C)

llvm/lib/CodeGen/AsmPrinter/AIXException.cpp

void AIXException::endFunction(const MachineFunction *MF) {
   if (!TargetLoweringObjectFileXCOFF::ShouldEmitEHBlock(MF))
     return;
 
   const MCSymbol *LSDALabel = emitExceptionTable();
 
   const Function &F = MF->getFunction();
   assert(F.hasPersonalityFn() &&
          "Landingpads are presented, but no personality routine is found.");
-  const Function *Per =
-      dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
+  const GlobalValue *Per =
+      dyn_cast<GlobalValue>(F.getPersonalityFn()->stripPointerCasts());
   const MCSymbol *PerSym = Asm->TM.getSymbol(Per);
 
   emitExceptionInfoTable(LSDALabel, PerSym);
 }
 
 } // End of namespace llvm

llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp

bool TargetLoweringObjectFileXCOFF::ShouldEmitEHBlock(
     const MachineFunction *MF) {
   if (!MF->getLandingPads().empty())
     return true;
 
   const Function &F = MF->getFunction();
   if (!F.hasPersonalityFn() || !F.needsUnwindTableEntry())
     return false;
 
-  const Function *Per =
-      dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
+  const GlobalValue *Per =
+      dyn_cast<GlobalValue>(F.getPersonalityFn()->stripPointerCasts());
+  assert(Per && "Personality routine is not a GlobalValue type.");
   if (isNoOpWithoutInvoke(classifyEHPersonality(Per)))
     return false;
 
   return true;
 }
 
 MCSymbol *
 TargetLoweringObjectFileXCOFF::getEHInfoTableSymbol(const MachineFunction *MF) {

llvm/test/CodeGen/PowerPC/aix-personality-alias.ll

+;; Test if we are still able to compile even when the personality routine is just an alias.
+
+; RUN: llc  -verify-machineinstrs -mcpu=pwr7 -mattr=-altivec \
+; RUN:      -mtriple powerpc-ibm-aix-xcoff < %s | FileCheck %s --check-prefixes=SYM,SYM32
+; RUN: llc  -verify-machineinstrs -mcpu=pwr7 -mattr=-altivec \
+; RUN:      -mtriple powerpc64-ibm-aix-xcoff < %s | FileCheck %s --check-prefixes=SYM,SYM64
+
+@__xlcxx_personality_v1 = alias i32 (), i32 ()* @__gxx_personality_v0
+define i32 @__gxx_personality_v0() {
+entry:
+  ret i32 1
+}
+
+define dso_local signext i32 @_Z3foov() #0 personality i8* bitcast (i32 ()* @__xlcxx_personality_v1 to i8*) {
+entry:
+  %retval = alloca i32, align 4
+  %exn.slot = alloca i8*, align 8
+  %ehselector.slot = alloca i32, align 4
+  invoke void @_Z3barv()
+          to label %invoke.cont unwind label %lpad
+
+invoke.cont:                                      ; preds = %entry
+  br label %try.cont
+
+lpad:                                             ; preds = %entry
+  %0 = landingpad { i8*, i32 }
+          catch i8* null
+  %1 = extractvalue { i8*, i32 } %0, 0
+  store i8* %1, i8** %exn.slot, align 8
+  %2 = extractvalue { i8*, i32 } %0, 1
+  store i32 %2, i32* %ehselector.slot, align 4
+  br label %catch
+
+catch:                                            ; preds = %lpad
+  %exn = load i8*, i8** %exn.slot, align 8
+  br label %return
+
+try.cont:                                         ; preds = %invoke.cont
+  store i32 2, i32* %retval, align 4
+  br label %return
+
+return:                                           ; preds = %try.cont, %catch
+  ret i32 1
+}
+
+declare void @_Z3barv()
+
+;   SYM:    .globl  __gxx_personality_v0[DS]        # -- Begin function __gxx_personality_v0
+;   SYM:    .globl  .__gxx_personality_v0
+;   SYM:    .align  4
+;   SYM:    .csect __gxx_personality_v0[DS]
+;   SYM:  __xlcxx_personality_v1:                 # @__gxx_personality_v0
+; SYM32:    .vbyte  4, .__gxx_personality_v0
+; SYM32:    .vbyte  4, TOC[TC0]
+; SYM32:    .vbyte  4, 0
+; SYM64:    .vbyte  8, .__gxx_personality_v0
+; SYM64:    .vbyte  8, TOC[TC0]
+; SYM64:    .vbyte  8, 0
+;   SYM:    .csect .text[PR],2
+;   SYM:  .__gxx_personality_v0:
+;   SYM:  .__xlcxx_personality_v1:
+;   SYM:  # %bb.0:                                # %entry
+;   SYM:    li 3, 1
+;   SYM:    blr
+
+;   SYM:    .csect .eh_info_table[RW],2
+;   SYM:  __ehinfo.1:
+;   SYM:    .vbyte  4, 0
+; SYM32:    .align  2
+; SYM32:    .vbyte  4, GCC_except_table1
+; SYM32:    .vbyte  4, __xlcxx_personality_v1
+; SYM64:    .align  3
+; SYM64:    .vbyte  8, GCC_except_table1
+; SYM64:    .vbyte  8, __xlcxx_personality_v1