[CilkSanitizer][CSI] Avoid inserting hooks or PHI nodes in placeholder

destinations of task exits.

This commit addresses llvm#62.

llvm/lib/Transforms/Instrumentation/CilkSanitizer.cpp

@@ -4145,6 +4145,10 @@ bool CilkSanitizerImpl::instrumentDetach(DetachInst *DI, unsigned SyncRegNum,
 
     Value *DefaultID = getDefaultID(IDBuilder);
     for (Spindle *SharedEH : SharedEHExits) {
+      // Skip shared-eh spindle exits that are placeholder unreachable blocks.
+      if (isa<UnreachableInst>(
+              SharedEH->getEntry()->getFirstNonPHIOrDbgOrLifetime()))
+        continue;
       CsiTaskExitProperty ExitProp;
       ExitProp.setIsTapirLoopBody(TapirLoopBody);
       insertHookCallAtSharedEHSpindleExits(

llvm/lib/Transforms/Instrumentation/ComprehensiveStaticInstrumentation.cpp

@@ -1287,6 +1287,10 @@ void CSIImpl::instrumentDetach(DetachInst *DI, DominatorTree *DT, TaskInfo &TI,
 
     Value *DefaultID = getDefaultID(IDBuilder);
     for (Spindle *SharedEH : SharedEHExits) {
+      // Skip shared-eh spindle exits that are placeholder unreachable blocks.
+      if (isa<UnreachableInst>(
+              SharedEH->getEntry()->getFirstNonPHIOrDbgOrLifetime()))
+        continue;
       CsiTaskExitProperty ExitProp;
       ExitProp.setIsTapirLoopBody(TapirLoopBody);
       insertHookCallAtSharedEHSpindleExits(

llvm/test/Transforms/Tapir/CilkSanitizer/cilksan-unreachable-sharedeh.ll

@@ -0,0 +1,138 @@
+; Check that CilkSanitizer and CSI do not insert hooks for phi nodes
+; at placeholder destinations of task exits.
+;
+; RUN: opt < %s -csan -S | FileCheck %s
+; RUN: opt < %s -passes='cilksan' -S | FileCheck %s
+; RUN: opt < %s -csi -S | FileCheck %s
+; RUN: opt < %s -passes='csi' -S | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: sanitize_cilk
+define dso_local i32 @compute() #0 {
+entry:
+  %syncreg59 = call token @llvm.syncregion.start()
+  %syncreg123 = call token @llvm.syncregion.start()
+  br label %lor.lhs.false
+
+lor.lhs.false:                                    ; preds = %entry
+  br label %lor.lhs.false6
+
+lor.lhs.false6:                                   ; preds = %lor.lhs.false
+  br label %lor.lhs.false8
+
+lor.lhs.false8:                                   ; preds = %lor.lhs.false6
+  br label %if.end
+
+if.end:                                           ; preds = %lor.lhs.false8
+  br label %pfor.end
+
+pfor.end:                                         ; preds = %if.end
+  br label %lor.lhs.false48
+
+lor.lhs.false48:                                  ; preds = %pfor.end
+  br label %lor.lhs.false50
+
+lor.lhs.false50:                                  ; preds = %lor.lhs.false48
+  br label %lor.lhs.false52
+
+lor.lhs.false52:                                  ; preds = %lor.lhs.false50
+  br label %lor.lhs.false54
+
+lor.lhs.false54:                                  ; preds = %lor.lhs.false52
+  br label %if.end58
+
+if.end58:                                         ; preds = %lor.lhs.false54
+  br i1 undef, label %pfor.ph63, label %pfor.end112
+
+pfor.ph63:                                        ; preds = %if.end58
+  br label %pfor.cond70
+
+pfor.cond70:                                      ; preds = %pfor.inc107, %pfor.ph63
+  br label %pfor.detach71
+
+pfor.detach71:                                    ; preds = %pfor.cond70
+  detach within %syncreg59, label %pfor.body.entry74, label %pfor.inc107
+
+pfor.body.entry74:                                ; preds = %pfor.detach71
+  br label %pfor.body76
+
+pfor.body76:                                      ; preds = %pfor.body.entry74
+  %call77 = call i32 undef()
+  br label %pfor.preattach106
+
+pfor.preattach106:                                ; preds = %pfor.body76
+  reattach within %syncreg59, label %pfor.inc107
+
+pfor.inc107:                                      ; preds = %pfor.preattach106, %pfor.detach71
+  br label %pfor.cond70
+
+pfor.end112:                                      ; preds = %if.end58
+  br label %lor.lhs.false118
+
+lor.lhs.false118:                                 ; preds = %pfor.end112
+  br label %if.end122
+
+if.end122:                                        ; preds = %lor.lhs.false118
+  br label %pfor.ph127
+
+pfor.ph127:                                       ; preds = %if.end122
+  br label %pfor.cond134
+
+pfor.cond134:                                     ; preds = %pfor.inc173, %pfor.ph127
+  br label %pfor.detach135
+
+pfor.detach135:                                   ; preds = %pfor.cond134
+  detach within %syncreg123, label %pfor.body.entry138, label %pfor.inc173
+
+pfor.body.entry138:                               ; preds = %pfor.detach135
+  br label %pfor.body140
+
+pfor.body140:                                     ; preds = %pfor.body.entry138
+  %call142 = call i32 undef()
+  br label %if.end168
+
+if.end168:                                        ; preds = %pfor.body140
+  br label %pfor.preattach172
+
+pfor.preattach172:                                ; preds = %if.end168
+  reattach within %syncreg123, label %pfor.inc173
+
+pfor.inc173:                                      ; preds = %pfor.preattach172, %pfor.detach135
+  br label %pfor.cond134
+}
+
+; CHECK: detach within %syncreg59, label %pfor.body.entry74, label %pfor.inc107 unwind label %{{.+}}
+; CHECK: invoke i32
+; CHECK-NEXT: to label %{{.+}} unwind label %[[CSI_CLEANUP_TASK:.+]]
+
+; CHECK: detach within %syncreg123, label %pfor.body.entry138, label %pfor.inc173 unwind label %{{.+}}
+; CHECK: invoke i32
+; CHECK-NEXT: to label %{{.+}} unwind label %[[CSI_CLEANUP_TASK2:.+]]
+
+; CHECK: csi.cleanup.unreachable:
+; CHECK-NOT: phi
+; CHECK: unreachable
+
+; CHECK: [[CSI_CLEANUP_TASK2]]:
+; CHECK: invoke void @llvm.detached.rethrow.sl_p0i8i32s(
+; CHECK-NEXT: to label %csi.cleanup.unreachable unwind label %{{.+}}
+
+; CHECK: [[CSI_CLEANUP_TASK]]:
+; CHECK: invoke void @llvm.detached.rethrow.sl_p0i8i32s(
+; CHECK-NEXT: to label %csi.cleanup.unreachable unwind label %{{.+}}
+
+; Function Attrs: argmemonly nounwind willreturn
+declare token @llvm.syncregion.start() #1
+
+; Function Attrs: argmemonly willreturn
+declare void @llvm.sync.unwind(token) #2
+
+; Function Attrs: argmemonly nofree nosync nounwind willreturn
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* noalias nocapture writeonly, i8* noalias nocapture readonly, i64, i1 immarg) #3
+
+attributes #0 = { sanitize_cilk }
+attributes #1 = { argmemonly nounwind willreturn }
+attributes #2 = { argmemonly willreturn }
+attributes #3 = { argmemonly nofree nosync nounwind willreturn }