[WinEH] Update LCSSA to handle catchswitch with handlers inside and o…

…utside a loop

Differential Revision: http://reviews.llvm.org/D15630

llvm-svn: 256005

llvm/lib/Analysis/LoopInfo.cpp

@@ -179,7 +179,13 @@ PHINode *Loop::getCanonicalInductionVariable() const {
 bool Loop::isLCSSAForm(DominatorTree &DT) const {
   for (block_iterator BI = block_begin(), E = block_end(); BI != E; ++BI) {
     BasicBlock *BB = *BI;
-    for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;++I)
+    for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;++I) {
+      // Tokens can't be used in PHI nodes and live-out tokens prevent loop
+      // optimizations, so for the purposes of considered LCSSA form, we
+      // can ignore them.
+      if (I->getType()->isTokenTy())
+        continue;
+
       for (Use &U : I->uses()) {
         Instruction *UI = cast<Instruction>(U.getUser());
         BasicBlock *UserBB = UI->getParent();
@@ -195,6 +201,7 @@ bool Loop::isLCSSAForm(DominatorTree &DT) const {
             DT.isReachableFromEntry(UserBB))
           return false;
       }
+    }
   }
 
   return true;

llvm/lib/Transforms/Utils/LCSSA.cpp

@@ -66,6 +66,13 @@ static bool processInstruction(Loop &L, Instruction &Inst, DominatorTree &DT,
                                PredIteratorCache &PredCache, LoopInfo *LI) {
   SmallVector<Use *, 16> UsesToRewrite;
 
+  // Tokens cannot be used in PHI nodes, so we skip over them.
+  // We can run into tokens which are live out of a loop with catchswitch
+  // instructions in Windows EH if the catchswitch has one catchpad which
+  // is inside the loop and another which is not.
+  if (Inst.getType()->isTokenTy())
+    return false;
+
   BasicBlock *InstBB = Inst.getParent();
 
   for (Use &U : Inst.uses()) {

llvm/test/Transforms/LCSSA/mixed-catch.ll

@@ -0,0 +1,95 @@
+; RUN: opt -lcssa -S < %s | FileCheck %s
+
+; This test is based on the following C++ code:
+;
+; void f()
+; {
+;   for (int i=0; i<12; i++) {
+;     try {
+;       if (i==3)
+;         throw i;
+;     } catch (int) {
+;       continue;
+;     } catch (...) { }
+;     if (i==3) break;
+;   }
+; }
+;
+; The loop info analysis identifies the catch pad for the second catch as being
+; outside the loop (because it returns to %for.end) but the associated
+; catchswitch block is identified as being inside the loop.  Because of this
+; analysis, the LCSSA pass wants to create a PHI node in the catchpad block
+; for the catchswitch value, but this is a token, so it can't.
+
+define void @f() personality i8* bitcast (i32 (...)* @__CxxFrameHandler3 to i8*) {
+entry:
+  %tmp = alloca i32, align 4
+  %i7 = alloca i32, align 4
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
+  %cmp = icmp slt i32 %i.0, 12
+  br i1 %cmp, label %for.body, label %for.end
+
+for.body:                                         ; preds = %for.cond
+  %cond = icmp eq i32 %i.0, 3
+  br i1 %cond, label %if.then, label %for.inc
+
+if.then:                                          ; preds = %for.body
+  store i32 %i.0, i32* %tmp, align 4
+  %tmp1 = bitcast i32* %tmp to i8*
+  invoke void @_CxxThrowException(i8* %tmp1, %eh.ThrowInfo* nonnull @_TI1H) #1
+          to label %unreachable unwind label %catch.dispatch
+
+catch.dispatch:                                   ; preds = %if.then
+  %tmp2 = catchswitch within none [label %catch, label %catch2] unwind to caller
+
+catch:                                            ; preds = %catch.dispatch
+  %tmp3 = catchpad within %tmp2 [%rtti.TypeDescriptor2* @"\01??_R0H@8", i32 0, i32* %i7]
+  catchret from %tmp3 to label %for.inc
+
+catch2:                                           ; preds = %catch.dispatch
+  %tmp4 = catchpad within %tmp2 [i8* null, i32 64, i8* null]
+  catchret from %tmp4 to label %for.end
+
+for.inc:                                          ; preds = %catch, %for.body
+  %inc = add nsw i32 %i.0, 1
+  br label %for.cond
+
+for.end:                                          ; preds = %catch2, %for.cond
+  ret void
+
+unreachable:                                      ; preds = %if.then
+  unreachable
+}
+
+; CHECK-LABEL: define void @f()
+; CHECK: catch2:
+; CHECK-NOT: phi
+; CHECK:   %tmp4 = catchpad within %tmp2
+; CHECK:   catchret from %tmp4 to label %for.end
+
+%rtti.TypeDescriptor2 = type { i8**, i8*, [3 x i8] }
+%eh.CatchableType = type { i32, i32, i32, i32, i32, i32, i32 }
+%eh.CatchableTypeArray.1 = type { i32, [1 x i32] }
+%eh.ThrowInfo = type { i32, i32, i32, i32 }
+
+$"\01??_R0H@8" = comdat any
+
+$"_CT??_R0H@84" = comdat any
+
+$_CTA1H = comdat any
+
+$_TI1H = comdat any
+
+@"\01??_7type_info@@6B@" = external constant i8*
+@"\01??_R0H@8" = linkonce_odr global %rtti.TypeDescriptor2 { i8** @"\01??_7type_info@@6B@", i8* null, [3 x i8] c".H\00" }, comdat
+@__ImageBase = external constant i8
+@"_CT??_R0H@84" = linkonce_odr unnamed_addr constant %eh.CatchableType { i32 1, i32 trunc (i64 sub nuw nsw (i64 ptrtoint (%rtti.TypeDescriptor2* @"\01??_R0H@8" to i64), i64 ptrtoint (i8* @__ImageBase to i64)) to i32), i32 0, i32 -1, i32 0, i32 4, i32 0 }, section ".xdata", comdat
+@_CTA1H = linkonce_odr unnamed_addr constant %eh.CatchableTypeArray.1 { i32 1, [1 x i32] [i32 trunc (i64 sub nuw nsw (i64 ptrtoint (%eh.CatchableType* @"_CT??_R0H@84" to i64), i64 ptrtoint (i8* @__ImageBase to i64)) to i32)] }, section ".xdata", comdat
+@_TI1H = linkonce_odr unnamed_addr constant %eh.ThrowInfo { i32 0, i32 0, i32 0, i32 trunc (i64 sub nuw nsw (i64 ptrtoint (%eh.CatchableTypeArray.1* @_CTA1H to i64), i64 ptrtoint (i8* @__ImageBase to i64)) to i32) }, section ".xdata", comdat
+
+declare void @_CxxThrowException(i8*, %eh.ThrowInfo*)
+
+declare i32 @__CxxFrameHandler3(...)