[llvm] 98eb917 - [LoopFlatten] Forget all block and loop dispositions after flatten

[via llvm-commits]

Author: luxufan
Date: 2022-11-14T10:19:11+08:00
New Revision: 98eb9179398d1e69e1f4416b1ef3bf308171684b

URL: https://github.com/llvm/llvm-project/commit/98eb9179398d1e69e1f4416b1ef3bf308171684b
DIFF: https://github.com/llvm/llvm-project/commit/98eb9179398d1e69e1f4416b1ef3bf308171684b.diff

LOG: [LoopFlatten] Forget all block and loop dispositions after flatten

Method forgetLoop only forgets expression of phi or its users. SCEV
expressions except the above mentioned may still has loop dispositions
that point to the destroyed loop, which might cause a crash.

Fixes: https://github.com/llvm/llvm-project/issues/58865

Reviewed By: nikic, fhahn

Differential Revision: https://reviews.llvm.org/D137651

Added: 
    llvm/test/Transforms/LoopFlatten/pr58865.ll

Modified: 
    llvm/lib/Transforms/Scalar/LoopFlatten.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/LoopFlatten.cpp b/llvm/lib/Transforms/Scalar/LoopFlatten.cpp
index c530e77c844f8..7388c3a90227d 100644
--- a/llvm/lib/Transforms/Scalar/LoopFlatten.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopFlatten.cpp
@@ -762,6 +762,7 @@ static bool DoFlattenLoopPair(FlattenInfo &FI, DominatorTree *DT, LoopInfo *LI,
   // deleted, and any information that have about the outer loop invalidated.
   SE->forgetLoop(FI.OuterLoop);
   SE->forgetLoop(FI.InnerLoop);
+  SE->forgetBlockAndLoopDispositions();
   if (U)
     U->markLoopAsDeleted(*FI.InnerLoop, FI.InnerLoop->getName());
   LI->erase(FI.InnerLoop);

diff  --git a/llvm/test/Transforms/LoopFlatten/pr58865.ll b/llvm/test/Transforms/LoopFlatten/pr58865.ll
new file mode 100644
index 0000000000000..984fd1fd1858a
--- /dev/null
+++ b/llvm/test/Transforms/LoopFlatten/pr58865.ll
@@ -0,0 +1,51 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -loop-flatten -verify-scev -S < %s | FileCheck %s
+;
+define void @sum_2d(ptr %p) {
+; CHECK-LABEL: @sum_2d(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[FLATTEN_TRIPCOUNT:%.*]] = mul i16 1, 1
+; CHECK-NEXT:    br label [[OUTER:%.*]]
+; CHECK:       outer:
+; CHECK-NEXT:    [[SUM_04:%.*]] = phi i16 [ 0, [[ENTRY:%.*]] ], [ [[DOTLCSSA:%.*]], [[OUTER_LATCH:%.*]] ]
+; CHECK-NEXT:    [[OUTER_IV:%.*]] = phi i16 [ 0, [[ENTRY]] ], [ [[OUTER_IV_NEXT:%.*]], [[OUTER_LATCH]] ]
+; CHECK-NEXT:    br label [[INNER:%.*]]
+; CHECK:       inner:
+; CHECK-NEXT:    [[SUM_12:%.*]] = phi i16 [ [[SUM_04]], [[OUTER]] ]
+; CHECK-NEXT:    [[INNER_IV:%.*]] = phi i16 [ 0, [[OUTER]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = load i16, ptr [[P:%.*]], align 1
+; CHECK-NEXT:    [[INNER_IV_NEXT:%.*]] = add nsw i16 [[INNER_IV]], 1
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i16 [[INNER_IV]], 0
+; CHECK-NEXT:    br label [[OUTER_LATCH]]
+; CHECK:       outer.latch:
+; CHECK-NEXT:    [[DOTLCSSA]] = phi i16 [ [[TMP0]], [[INNER]] ]
+; CHECK-NEXT:    [[OUTER_IV_NEXT]] = add nsw i16 [[OUTER_IV]], 1
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i16 [[OUTER_IV_NEXT]], [[FLATTEN_TRIPCOUNT]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[OUTER]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %outer
+
+outer:                                         ; preds = %outer.latch, %entry
+  %sum.04 = phi i16 [ 0, %entry ], [ %0, %outer.latch ]
+  %outer.iv = phi i16 [ 0, %entry ], [ %outer.iv.next, %outer.latch ]
+  br label %inner
+
+inner:                                        ; preds = %inner, %outer
+  %sum.12 = phi i16 [ %sum.04, %outer ], [ %0, %inner ]
+  %inner.iv = phi i16 [ 0, %outer ], [ %inner.iv.next, %inner ]
+  %0 = load i16, ptr %p, align 1
+  %inner.iv.next = add nsw i16 %inner.iv, 1
+  %cmp2 = icmp slt i16 %inner.iv, 0
+  br i1 %cmp2, label %inner, label %outer.latch
+
+outer.latch:                                         ; preds = %inner
+  %outer.iv.next = add nsw i16 %outer.iv, 1
+  %cmp = icmp slt i16 %outer.iv.next, 0
+  br i1 %cmp, label %outer, label %exit
+
+exit:                                         ; preds = %outer.latch
+  ret void
+}