[LoopStripMine] Fix loop stripmining to handle Tapir loops where the …

…tripcount and primary induction variable have different types.

llvm/lib/Transforms/Tapir/LoopStripMine.cpp

@@ -254,6 +254,17 @@ static Task *getTapirLoopForStripMining(const Loop *L, TaskInfo &TI,
     return nullptr;
   }
 
+  // Tapir loops where the loop body does not reattach cannot be stripmined.
+  if (!llvm::any_of(predecessors(LatchBlock), [](const BasicBlock *B) {
+        return isa<ReattachInst>(B->getTerminator());
+      })) {
+    LLVM_DEBUG(dbgs() << "  Can't stripmine: loop body does not reattach.\n");
+    if (ORE)
+      ORE->emit(TapirLoopInfo::createMissedAnalysis(LSM_NAME, "NoReattach", L)
+                << "spawned loop body does not reattach");
+    return nullptr;
+  }
+
   // The current loop-stripmine pass can only stripmine loops with a single
   // latch that's a conditional branch exiting the loop.
   // FIXME: The implementation can be extended to work with more complicated
@@ -1175,6 +1186,7 @@ Loop *llvm::StripMineLoop(
       ReattachDom = DT->findNearestCommonDominator(ReattachDom, I->getParent());
     ReplaceInstWithInst(I, BranchInst::Create(Latch));
   }
+  assert(ReattachDom && "No reattach-dominator block found");
   // Insert a reattach at the end of NewReattB.
   ReplaceInstWithInst(NewReattB->getTerminator(),
                       ReattachInst::Create(NewLatch, NewSyncReg));
@@ -1330,7 +1342,7 @@ Loop *llvm::StripMineLoop(
   // Update all of the old PHI nodes
   B2.SetInsertPoint(NewEntry->getTerminator());
   Instruction *CountVal = cast<Instruction>(
-      B2.CreateMul(ConstantInt::get(PrimaryInduction->getType(), Count),
+      B2.CreateMul(ConstantInt::get(NewIdx->getType(), Count),
                    NewIdx));
   CountVal->copyIRFlags(PrimaryInduction);
   for (auto &InductionEntry : *TL.getInductionVars()) {

llvm/lib/Transforms/Tapir/LoopStripMinePass.cpp

@@ -284,7 +284,7 @@ static bool tryToStripMineLoop(
     return false;
 
   // Copy metadata to remainder loop
-  if (RemainderLoop) {
+  if (RemainderLoop && OrigLoopID) {
     // Optional<MDNode *> RemainderLoopID = makeFollowupLoopID(
     //     OrigLoopID, {}, "tapir.loop");
     MDNode *NewRemainderLoopID =

llvm/lib/Transforms/Utils/TapirUtils.cpp

@@ -838,7 +838,7 @@ void llvm::SerializeDetach(DetachInst *DI, BasicBlock *ParentEntry,
 
   // Update dominator tree.
   if (DT) {
-    if (DT->dominates(Spawner, Continue))
+    if (ReattachDom && DT->dominates(Spawner, Continue))
       DT->changeImmediateDominator(Continue, ReattachDom);
     if (DI->hasUnwindDest())
       DT->deleteEdge(Spawner, Unwind);

llvm/test/Transforms/Tapir/loop-stripmine-iv-tripcount-type-mismatch.ll

@@ -0,0 +1,111 @@
+; Check that loop stripmining properly handles Tapir loops where the
+; primary IV and the tripcount have different types.
+;
+; RUN: opt < %s -loop-stripmine -S -o - | FileCheck %s
+; RUN: opt < %s -passes='loop-stripmine' -S -o - | 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: argmemonly nounwind willreturn
+declare token @llvm.syncregion.start() #0
+
+define dso_local fastcc void @_ZL9conj_gradPiS_PdS0_S0_S0_S0_S0_S0_S0_() unnamed_addr #1 {
+entry:
+  %syncreg143 = tail call token @llvm.syncregion.start()
+  detach within %syncreg143, label %pfor.body.i, label %pfor.inc.i
+
+pfor.body.i:                                      ; preds = %entry
+  unreachable
+
+pfor.inc.i:                                       ; preds = %entry
+  sync within %syncreg143, label %_Z10initializePdS_S_S_S_mm.exit
+
+_Z10initializePdS_S_S_S_mm.exit:                  ; preds = %pfor.inc.i
+  detach within %syncreg143, label %pfor.body, label %pfor.inc
+
+pfor.body:                                        ; preds = %_Z10initializePdS_S_S_S_mm.exit
+  unreachable
+
+pfor.inc:                                         ; preds = %_Z10initializePdS_S_S_S_mm.exit
+  sync within %syncreg143, label %sync.continue
+
+sync.continue:                                    ; preds = %pfor.inc
+  detach within %syncreg143, label %pfor.body.i122, label %pfor.inc.i124
+
+pfor.body.i122:                                   ; preds = %sync.continue
+  unreachable
+
+pfor.inc.i124:                                    ; preds = %sync.continue
+  sync within %syncreg143, label %pfor.cond.i136
+
+pfor.cond.i136:                                   ; preds = %pfor.inc.i124
+  detach within %syncreg143, label %pfor.body.i142, label %pfor.inc.i144
+
+pfor.body.i142:                                   ; preds = %pfor.cond.i136
+  unreachable
+
+pfor.inc.i144:                                    ; preds = %pfor.cond.i136
+  sync within %syncreg143, label %cleanup.tf.tfend
+
+cleanup.tf.tfend:                                 ; preds = %pfor.inc.i144
+  detach within %syncreg143, label %pfor.body.i105, label %pfor.inc.i107
+
+pfor.body.i105:                                   ; preds = %cleanup.tf.tfend
+  unreachable
+
+pfor.inc.i107:                                    ; preds = %cleanup.tf.tfend
+  sync within %syncreg143, label %_Z11map_add_mulPdS_S_dmm.exit.tfend.tfend
+
+_Z11map_add_mulPdS_S_dmm.exit.tfend.tfend:        ; preds = %pfor.inc.i107
+  detach within %syncreg143, label %pfor.body73, label %pfor.inc101
+
+pfor.body73:                                      ; preds = %_Z11map_add_mulPdS_S_dmm.exit.tfend.tfend
+  unreachable
+
+pfor.inc101:                                      ; preds = %_Z11map_add_mulPdS_S_dmm.exit.tfend.tfend
+  sync within %syncreg143, label %sync.continue106
+
+sync.continue106:                                 ; preds = %pfor.inc101
+  br label %pfor.cond157
+
+pfor.cond157:                                     ; preds = %pfor.inc177, %sync.continue106
+  %indvars.iv164 = phi i64 [ 0, %sync.continue106 ], [ %indvars.iv.next165, %pfor.inc177 ]
+  %indvars.iv.next165 = add nuw nsw i64 %indvars.iv164, 1
+  detach within %syncreg143, label %pfor.body163, label %pfor.inc177
+
+pfor.body163:                                     ; preds = %pfor.cond157
+  reattach within %syncreg143, label %pfor.inc177
+
+pfor.inc177:                                      ; preds = %pfor.body163, %pfor.cond157
+  %lftr.wideiv = trunc i64 %indvars.iv.next165 to i32
+  %exitcond = icmp eq i32 undef, %lftr.wideiv
+  br i1 %exitcond, label %pfor.cond.cleanup180, label %pfor.cond157
+
+; CHECK: pfor.cond157.strpm.outer:
+; CHECK: %[[NITER:.+]] = phi i32 [ 0, %sync.continue106.new ], [ %[[NITER_ADD:.+]], %pfor.inc177.strpm.outer ]
+; CHECK: detach within %syncreg143, label %pfor.body163.strpm.outer, label %pfor.inc177.strpm.outer
+
+; CHECK: pfor.body163.strpm.outer:
+; CHECK: mul i32 2048, %[[NITER]]
+
+; CHECK: pfor.inc177.strpm.outer:
+; CHECK: %[[NITER_ADD]] = add {{.*}}i32 %[[NITER]], 1
+
+; CHECK: pfor.cond157.epil:
+; CHECK: %[[INDVAR_EPIL:.+]] = phi i64
+; CHECK: %[[EPIL_ITER:.+]] = phi i32
+
+; CHECK: pfor.inc177.epil:
+; CHECK: %[[EPIL_ITER_SUB:.+]] = sub i32 %[[EPIL_ITER]], 1
+; CHECK: icmp ne i32 %[[EPIL_ITER_SUB]], 0
+
+pfor.cond.cleanup180:                             ; preds = %pfor.inc177
+  unreachable
+}
+
+attributes #0 = { argmemonly nounwind willreturn }
+attributes #1 = { "use-soft-float"="false" }
+
+!llvm.ident = !{!0}
+
+!0 = !{!"clang version 10.0.1 ([email protected]:neboat/opencilk-project.git 2c7e581b441a9ae5682f02090613d00aaa26460d)"}