!fixup add dbg message

Author: fhahn

llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp

@@ -1375,10 +1375,17 @@ bool LoopVectorizationLegality::isFixedOrderRecurrence(
 }
 
 bool LoopVectorizationLegality::blockNeedsPredication(BasicBlock *BB) const {
-  // When vectorizing early exits, create predicates for all blocks, except the
-  // header.
-  if (hasUncountableEarlyExit() && BB != TheLoop->getHeader())
-    return true;
+  // When vectorizing early exits, create predicates for the latch block. The
+  // early exiting block must be a direct predecessor of the latch at the
+  // moment.
+  BasicBlock *Latch = TheLoop->getLoopLatch();
+  if (hasUncountableEarlyExit()) {
+    assert(
+        getUncountableExitingBlocks().size() == 1 &&
+        is_contained(predecessors(Latch), getUncountableExitingBlocks()[0]) &&
+        "Uncountable exiting block must be a direct predecessor of latch");
+    return BB == Latch;
+  }
   return LoopAccessInfo::blockNeedsPredication(BB, TheLoop, DT);
 }
 

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -9239,8 +9239,13 @@ LoopVectorizationPlanner::tryToBuildVPlanWithVPRecipes(VFRange &Range) {
   SetVector<VPIRInstruction *> ExitUsersToFix = collectUsersInExitBlocks(
       OrigLoop, RecipeBuilder, *Plan, Legal->getInductionVars());
   addExitUsersForFirstOrderRecurrences(*Plan, ExitUsersToFix);
-  if (!addUsersInExitBlocks(*Plan, ExitUsersToFix))
+  if (!addUsersInExitBlocks(*Plan, ExitUsersToFix)) {
+    reportVectorizationFailure(
+        "Some exit values in loop with uncountable exit not supported yet",
+        "Some exit values in loop with uncountable exit not supported yet",
+        "UncountableEarlyExitLoopsUnsupportedExitValue", ORE, OrigLoop);
     return nullptr;
+  }
 
   // ---------------------------------------------------------------------------
   // Transform initial VPlan: Apply previously taken decisions, in order, to

llvm/test/Transforms/LoopVectorize/early_exit_legality.ll

@@ -11,7 +11,7 @@ define i32 @diff_exit_block_needs_scev_check(i32 %end) {
 ; CHECK-LABEL: LV: Checking a loop in 'diff_exit_block_needs_scev_check'
 ; CHECK:       Found an early exit loop with symbolic max backedge taken count: (-1 + (1 umax (zext i10 (trunc i32 %end to i10) to i32)))<nsw>
 ; CHECK-NEXT:  LV: We can vectorize this loop!
-; CHECK-NEXT:  LV: Not vectorizing: Auto-vectorization of loops with uncountable early exit is not yet supported.
+; CHECK-NOT:   LV: Not vectorizing:
 entry:
   %p1 = alloca [1024 x i32]
   %p2 = alloca [1024 x i32]
@@ -49,7 +49,7 @@ define i64 @same_exit_block_pre_inc_use1() {
 ; CHECK-LABEL: LV: Checking a loop in 'same_exit_block_pre_inc_use1'
 ; CHECK:       LV: Found an early exit loop with symbolic max backedge taken count: 63
 ; CHECK-NEXT:  LV: We can vectorize this loop!
-; CHECK-NEXT:  LV: Not vectorizing: Auto-vectorization of loops with uncountable early exit is not yet supported.
+; CHECK-NOT:   LV: Not vectorizing
 entry:
   %p1 = alloca [1024 x i8]
   %p2 = alloca [1024 x i8]
@@ -141,7 +141,7 @@ define i64 @loop_contains_load_after_early_exit(ptr dereferenceable(1024) align(
 ; CHECK-LABEL: LV: Checking a loop in 'loop_contains_load_after_early_exit'
 ; CHECK:       LV: Found an early exit loop with symbolic max backedge taken count: 63
 ; CHECK-NEXT:  LV: We can vectorize this loop!
-; CHECK-NEXT:  LV: Not vectorizing: Auto-vectorization of loops with uncountable early exit is not yet supported.
+; CHECK:       LV: Not vectorizing: Some exit values in loop with uncountable exit not supported yet.
 entry:
   %p1 = alloca [1024 x i8]
   call void @init_mem(ptr %p1, i64 1024)