[llvm] d3f89d4 - Revert "[LoopInterchange] Fix legality for triangular loops"

via llvm-commits llvm-commits at lists.llvm.org
Tue May 11 15:13:44 PDT 2021


Author: Congzhe Cao
Date: 2021-05-11T18:10:58-04:00
New Revision: d3f89d4d16883b2bcf5f032152f10e384b53d92a

URL: https://github.com/llvm/llvm-project/commit/d3f89d4d16883b2bcf5f032152f10e384b53d92a
DIFF: https://github.com/llvm/llvm-project/commit/d3f89d4d16883b2bcf5f032152f10e384b53d92a.diff

LOG: Revert "[LoopInterchange] Fix legality for triangular loops"

This reverts commit 29342291d25b83da97e74d75004b177ba41114fc.

The test case requires an assert build. Will add REQUIRES and re-commit.

Added: 
    

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

Removed: 
    llvm/test/Transforms/LoopInterchange/inner-indvar-depend-on-outer-indvar.ll


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/LoopInterchange.cpp b/llvm/lib/Transforms/Scalar/LoopInterchange.cpp
index 58b456d5615fd..5aed49dccf820 100644
--- a/llvm/lib/Transforms/Scalar/LoopInterchange.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopInterchange.cpp
@@ -656,65 +656,6 @@ bool LoopInterchangeLegality::isLoopStructureUnderstood(
       return false;
     }
   }
-
-  // TODO: Handle triangular loops of another form.
-  // e.g. for(int i=0;i<N;i++)
-  //        for(int j=0;j<i;j++)
-  // or,
-  //      for(int i=0;i<N;i++)
-  //        for(int j=0;j*i<N;j++)
-  BasicBlock *InnerLoopLatch = InnerLoop->getLoopLatch();
-  BranchInst *InnerLoopLatchBI =
-      dyn_cast<BranchInst>(InnerLoopLatch->getTerminator());
-  if (!InnerLoopLatchBI->isConditional())
-    return false;
-  if (CmpInst *InnerLoopCmp =
-          dyn_cast<CmpInst>(InnerLoopLatchBI->getCondition())) {
-    Value *Op0 = InnerLoopCmp->getOperand(0);
-    Value *Op1 = InnerLoopCmp->getOperand(1);
-
-    // LHS and RHS of the inner loop exit condition, e.g.,
-    // in "for(int j=0;j<i;j++)", LHS is j and RHS is i.
-    Value *Left = nullptr;
-    Value *Right = nullptr;
-
-    // Check if V only involves inner loop induction variable.
-    // Return true if V is InnerInduction, or a cast from
-    // InnerInduction, or a binary operator that involves
-    // InnerInduction and a constant.
-    std::function<bool(Value *)> IsPathToIndVar;
-    IsPathToIndVar = [&InnerInduction, &IsPathToIndVar](Value *V) -> bool {
-      if (V == InnerInduction)
-        return true;
-      if (isa<Constant>(V))
-        return true;
-      Instruction *I = dyn_cast<Instruction>(V);
-      if (!I)
-        return false;
-      if (isa<CastInst>(I))
-        return IsPathToIndVar(I->getOperand(0));
-      if (isa<BinaryOperator>(I))
-        return IsPathToIndVar(I->getOperand(0)) &&
-               IsPathToIndVar(I->getOperand(1));
-      return false;
-    };
-
-    if (IsPathToIndVar(Op0) && !isa<Constant>(Op0)) {
-      Left = Op0;
-      Right = Op1;
-    } else if (IsPathToIndVar(Op1) && !isa<Constant>(Op1)) {
-      Left = Op1;
-      Right = Op0;
-    }
-
-    if (Left == nullptr)
-      return false;
-
-    const SCEV *S = SE->getSCEV(Right);
-    if (!SE->isLoopInvariant(S, OuterLoop))
-      return false;
-  }
-
   return true;
 }
 

diff  --git a/llvm/test/Transforms/LoopInterchange/inner-indvar-depend-on-outer-indvar.ll b/llvm/test/Transforms/LoopInterchange/inner-indvar-depend-on-outer-indvar.ll
deleted file mode 100644
index 9a571acc47ec9..0000000000000
--- a/llvm/test/Transforms/LoopInterchange/inner-indvar-depend-on-outer-indvar.ll
+++ /dev/null
@@ -1,152 +0,0 @@
-; RUN: opt < %s -basic-aa -loop-interchange -verify-dom-info -verify-loop-info \
-; RUN:     -S -debug 2>&1 | FileCheck %s
-
- at A = common global [100 x [100 x i64]] zeroinitializer
- at N = dso_local local_unnamed_addr global i64 100, align 8
-
-
-;;  for(int i=0;i<100;i++)
-;;    for(int j=0;j<i;j++)
-;;      A[j][i] = A[j][i]+k;
-
-;; Inner loop induction variable exit condition depends on the
-;; outer loop induction variable, i.e., triangular loops.
-; CHECK: Loop structure not understood by pass
-; CHECK: Not interchanging loops. Cannot prove legality.
-
-define void @interchange_01(i64 %k) {
-entry:
-  br label %for1.header
-
-for1.header:
-  %i = phi i64 [ 0, %entry ], [ %i.next, %for1.inc10 ]
-  br label %for2
-
-for2:
-  %j = phi i64 [ %j.next, %for2 ], [ 0, %for1.header ]
-  %arrayidx5 = getelementptr inbounds [100 x [100 x i64]], [100 x [100 x i64]]* @A, i64 0, i64 %j, i64 %i
-  %lv = load i64, i64* %arrayidx5
-  %add = add nsw i64 %lv, %k
-  store i64 %add, i64* %arrayidx5
-  %j.next = add nuw nsw i64 %j, 1
-  %exitcond = icmp eq i64 %j, %i
-  br i1 %exitcond, label %for1.inc10, label %for2
-
-for1.inc10:
-  %i.next = add nuw nsw i64 %i, 1
-  %exitcond26 = icmp eq i64 %i, 99
-  br i1 %exitcond26, label %for.end12, label %for1.header
-
-for.end12:
-  ret void
-}
-
-
-;;  for(int i=0;i<100;i++)
-;;    for(int j=0;j+i<100;j++)
-;;      A[j][i] = A[j][i]+k;
-
-;; Inner loop induction variable exit condition depends on the
-;; outer loop induction variable, i.e., triangular loops.
-; CHECK: Loop structure not understood by pass
-; CHECK: Not interchanging loops. Cannot prove legality.
-
-define void @interchange_02(i64 %k) {
-entry:
-  br label %for1.header
-
-for1.header:
-  %i = phi i64 [ 0, %entry ], [ %i.next, %for1.inc10 ]
-  br label %for2
-
-for2:
-  %j = phi i64 [ %j.next, %for2 ], [ 0, %for1.header ]
-  %arrayidx5 = getelementptr inbounds [100 x [100 x i64]], [100 x [100 x i64]]* @A, i64 0, i64 %j, i64 %i
-  %lv = load i64, i64* %arrayidx5
-  %add = add nsw i64 %lv, %k
-  store i64 %add, i64* %arrayidx5
-  %0 = add nuw nsw i64 %j, %i
-  %j.next = add nuw nsw i64 %j, 1
-  %exitcond = icmp eq i64 %0, 100
-  br i1 %exitcond, label %for1.inc10, label %for2
-
-for1.inc10:
-  %i.next = add nuw nsw i64 %i, 1
-  %exitcond26 = icmp eq i64 %i, 99
-  br i1 %exitcond26, label %for.end12, label %for1.header
-
-for.end12:
-  ret void
-}
-
-;;  for(int i=0;i<100;i++)
-;;    for(int j=0;i>j;j++)
-;;      A[j][i] = A[j][i]+k;
-
-;; Inner loop induction variable exit condition depends on the
-;; outer loop induction variable, i.e., triangular loops.
-; CHECK: Loop structure not understood by pass
-; CHECK: Not interchanging loops. Cannot prove legality.
-
-define void @interchange_03(i64 %k) {
-entry:
-  br label %for1.header
-
-for1.header:
-  %i = phi i64 [ 0, %entry ], [ %i.next, %for1.inc10 ]
-  br label %for2
-
-for2:
-  %j = phi i64 [ %j.next, %for2 ], [ 0, %for1.header ]
-  %arrayidx5 = getelementptr inbounds [100 x [100 x i64]], [100 x [100 x i64]]* @A, i64 0, i64 %j, i64 %i
-  %lv = load i64, i64* %arrayidx5
-  %add = add nsw i64 %lv, %k
-  store i64 %add, i64* %arrayidx5
-  %j.next = add nuw nsw i64 %j, 1
-  %exitcond = icmp ne i64 %i, %j
-  br i1 %exitcond, label %for2, label %for1.inc10
-
-for1.inc10:
-  %i.next = add nuw nsw i64 %i, 1
-  %exitcond26 = icmp eq i64 %i, 99
-  br i1 %exitcond26, label %for.end12, label %for1.header
-
-for.end12:
-  ret void
-}
-
-;;  for(int i=0;i<100;i++)
-;;    for(int j=0;N>j;j++)
-;;      A[j][i] = A[j][i]+k;
-
-;; Inner loop induction variable exit condition depends on
-;; an outer loop invariant, can do interchange.
-; CHECK: Loops interchanged
-
-define void @interchange_04(i64 %k) {
-entry:
-  %0 = load i64, i64* @N, align 4
-  br label %for1.header
-
-for1.header:
-  %i = phi i64 [ 0, %entry ], [ %i.next, %for1.inc10 ]
-  br label %for2
-
-for2:
-  %j = phi i64 [ %j.next, %for2 ], [ 0, %for1.header ]
-  %arrayidx5 = getelementptr inbounds [100 x [100 x i64]], [100 x [100 x i64]]* @A, i64 0, i64 %j, i64 %i
-  %lv = load i64, i64* %arrayidx5
-  %add = add nsw i64 %lv, %k
-  store i64 %add, i64* %arrayidx5
-  %j.next = add nuw nsw i64 %j, 1
-  %exitcond = icmp ne i64 %0, %j
-  br i1 %exitcond, label %for2, label %for1.inc10
-
-for1.inc10:
-  %i.next = add nuw nsw i64 %i, 1
-  %exitcond26 = icmp eq i64 %i, 99
-  br i1 %exitcond26, label %for.end12, label %for1.header
-
-for.end12:
-  ret void
-}


        


More information about the llvm-commits mailing list