Fix really stupid ARM EHABI info generation bug: we should not emit

eh table and handler data if there are no landing pads in the function.
Patch by Logan Chien with some cleanups from me.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167945 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/AsmPrinter/ARMException.cpp

@@ -69,22 +69,25 @@ void ARMException::EndFunction() {
     Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_end",
                                                   Asm->getFunctionNumber()));
 
-    // Emit references to personality.
-    if (const Function * Personality =
-        MMI->getPersonalities()[MMI->getPersonalityIndex()]) {
-      MCSymbol *PerSym = Asm->Mang->getSymbol(Personality);
-      Asm->OutStreamer.EmitSymbolAttribute(PerSym, MCSA_Global);
-      Asm->OutStreamer.EmitPersonality(PerSym);
-    }
-
     if (EnableARMEHABIDescriptors) {
       // Map all labels and get rid of any dead landing pads.
       MMI->TidyLandingPads();
 
-      Asm->OutStreamer.EmitHandlerData();
+      if (!MMI->getLandingPads().empty()) {
+        // Emit references to personality.
+        if (const Function * Personality =
+            MMI->getPersonalities()[MMI->getPersonalityIndex()]) {
+          MCSymbol *PerSym = Asm->Mang->getSymbol(Personality);
+          Asm->OutStreamer.EmitSymbolAttribute(PerSym, MCSA_Global);
+          Asm->OutStreamer.EmitPersonality(PerSym);
+        }
+
+        // Emit .handlerdata directive.
+        Asm->OutStreamer.EmitHandlerData();
 
-      // Emit actual exception table
-      EmitExceptionTable();
+        // Emit actual exception table
+        EmitExceptionTable();
+      }
     }
   }
 

test/CodeGen/ARM/ehabi-no-landingpad.ll

@@ -0,0 +1,18 @@
+; RUN: llc < %s -mtriple=armv7-unknown-linux-gnueabi \
+; RUN:   -arm-enable-ehabi -arm-enable-ehabi-descriptors | FileCheck %s
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:64:128-a0:0:64-n32-S64"
+target triple = "armv7-unknown-linux-gnueabi"
+
+define void @_Z4testv() {
+; CHECK: _Z4testv
+; CHECK: .fnstart
+; CHECK: .size
+; CHECK-NOT: .handlerdata
+; CHECK: .fnend
+entry:
+  call void @_Z15throw_exceptionv()
+  ret void
+}
+
+declare void @_Z15throw_exceptionv()