[llvm] [LoopInterchange] Reject interchange if non-reassociative reduction exists (PR #148612)

Ryotaro Kasuga via llvm-commits llvm-commits at lists.llvm.org
Mon Jul 14 04:38:22 PDT 2025


https://github.com/kasuga-fj created https://github.com/llvm/llvm-project/pull/148612

None

>From 34ce36c9bb657f1cb3ea93af33f387efd497adf8 Mon Sep 17 00:00:00 2001
From: Ryotaro Kasuga <kasuga.ryotaro at fujitsu.com>
Date: Mon, 14 Jul 2025 00:15:42 +0000
Subject: [PATCH] [LoopInterchange] Reject interchange if non-reassociative
 reduction exists

---
 .../lib/Transforms/Scalar/LoopInterchange.cpp |  57 +-
 .../Transforms/LoopInterchange/pr48212.ll     |   2 +-
 .../LoopInterchange/reductions-kind.ll        | 864 ++++++++++++++++++
 3 files changed, 921 insertions(+), 2 deletions(-)
 create mode 100644 llvm/test/Transforms/LoopInterchange/reductions-kind.ll

diff --git a/llvm/lib/Transforms/Scalar/LoopInterchange.cpp b/llvm/lib/Transforms/Scalar/LoopInterchange.cpp
index a5008907b9014..a2aa72e1a01f2 100644
--- a/llvm/lib/Transforms/Scalar/LoopInterchange.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopInterchange.cpp
@@ -812,7 +812,62 @@ static PHINode *findInnerReductionPhi(Loop *L, Value *V) {
         // Detect floating point reduction only when it can be reordered.
         if (RD.getExactFPMathInst() != nullptr)
           return nullptr;
-        return PHI;
+
+        RecurKind RK = RD.getRecurrenceKind();
+        switch (RK) {
+        case RecurKind::Or:
+        case RecurKind::And:
+        case RecurKind::Xor:
+        case RecurKind::SMin:
+        case RecurKind::SMax:
+        case RecurKind::UMin:
+        case RecurKind::UMax:
+        case RecurKind::FAdd:
+        case RecurKind::FMul:
+        case RecurKind::FMin:
+        case RecurKind::FMax:
+        case RecurKind::FMinimum:
+        case RecurKind::FMaximum:
+        case RecurKind::FMinimumNum:
+        case RecurKind::FMaximumNum:
+        case RecurKind::FMulAdd:
+        case RecurKind::AnyOf:
+          return PHI;
+
+        // Change the order of integer addition/multiplication may change the
+        // semantics. Consider the following case:
+        //
+        //  int A[2][2] = {{ INT_MAX, INT_MAX }, { INT_MIN, INT_MIN }};
+        //  int sum = 0;
+        //  for (int i = 0; i < 2; i++)
+        //    for (int j = 0; j < 2; j++)
+        //      sum += A[j][i];
+        //
+        // If the above loops are exchanged, the addition will cause an
+        // overflow. To prove the legality, we must ensure that all reduction
+        // operations don't have nuw/nsw flags.
+        case RecurKind::Add:
+        case RecurKind::Mul: {
+          unsigned OpCode = RecurrenceDescriptor::getOpcode(RK);
+          SmallVector<Instruction *, 4> Ops = RD.getReductionOpChain(PHI, L);
+
+          // FIXME: Is this check necessary?
+          if (Ops.empty())
+            return nullptr;
+          for (Instruction *I : Ops) {
+            // FIXME: Is this check necessary?
+            if (I->getOpcode() != OpCode)
+              return nullptr;
+
+            // Reject if the reduction operation has nuw/nsw flags.
+            if (I->hasNoSignedWrap() || I->hasNoUnsignedWrap())
+              return nullptr;
+          }
+          return PHI;
+        }
+        default:
+          return nullptr;
+        }
       }
       return nullptr;
     }
diff --git a/llvm/test/Transforms/LoopInterchange/pr48212.ll b/llvm/test/Transforms/LoopInterchange/pr48212.ll
index 936c53e217540..cb1300846cf0f 100644
--- a/llvm/test/Transforms/LoopInterchange/pr48212.ll
+++ b/llvm/test/Transforms/LoopInterchange/pr48212.ll
@@ -38,7 +38,7 @@ for.body3:                                        ; preds = %L2, %for.inc
   %idxprom4 = sext i32 %k1.03 to i64
   %arrayidx5 = getelementptr inbounds [5 x i32], ptr %arrayidx, i64 0, i64 %idxprom4
   %0 = load i32, ptr %arrayidx5
-  %add = add nsw i32 %temp.12, %0
+  %add = add i32 %temp.12, %0
   br label %for.inc
 
 for.inc:                                          ; preds = %for.body3
diff --git a/llvm/test/Transforms/LoopInterchange/reductions-kind.ll b/llvm/test/Transforms/LoopInterchange/reductions-kind.ll
new file mode 100644
index 0000000000000..d9e4d58a1780e
--- /dev/null
+++ b/llvm/test/Transforms/LoopInterchange/reductions-kind.ll
@@ -0,0 +1,864 @@
+; RUN: opt < %s -passes=loop-interchange -cache-line-size=64 -pass-remarks-output=%t -disable-output \
+; RUN:     -verify-dom-info -verify-loop-info -verify-loop-lcssa
+; RUN: FileCheck -input-file=%t %s
+
+; int sum = 0;
+; for (int i = 0; i < 2; i++)
+;   for (int j = 0; j < 2; j++)
+;     sum += A[j][i];
+
+; CHECK:      --- !Missed
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            UnsupportedPHIOuter
+; CHECK-NEXT: Function:        reduction_add
+define void @reduction_add(ptr %A) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %sum.i = phi i32 [ 0, %entry ], [ %sum.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %sum.j = phi i32 [ %sum.i, %for.i.header ], [ %sum.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load i32, ptr %idx, align 4
+  %sum.j.next = add nsw i32 %sum.j, %a
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %sum.i.lcssa = phi i32 [ %sum.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_wrap_add
+define void @reduction_wrap_add(ptr %A) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %sum.i = phi i32 [ 0, %entry ], [ %sum.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %sum.j = phi i32 [ %sum.i, %for.i.header ], [ %sum.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load i32, ptr %idx, align 4
+  %sum.j.next = add i32 %sum.j, %a
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %sum.i.lcssa = phi i32 [ %sum.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+; CHECK:      --- !Missed
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            UnsupportedPHIOuter
+; CHECK-NEXT: Function:        reduction_cast_add
+define void @reduction_cast_add(ptr %A) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %sum.i = phi i32 [ 0, %entry ], [ %sum.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %sum.j = phi i32 [ %sum.i, %for.i.header ], [ %sum.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load i32, ptr %idx, align 4
+  %sum.j.trunc = trunc i32 %sum.j to i16
+  %sum.j.ext = zext i16 %sum.j.trunc to i32
+  %sum.j.next = add nsw i32 %sum.j.ext, %a
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %sum.i.lcssa = phi i32 [ %sum.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+
+; int prod = 1;
+; for (int i = 0; i < 2; i++)
+;   for (int j = 0; j < 2; j++)
+;     prod *= A[j][i];
+
+; CHECK:      --- !Missed
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            UnsupportedPHIOuter
+; CHECK-NEXT: Function:        reduction_mul
+define void @reduction_mul(ptr %A) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %prod.i = phi i32 [ 1, %entry ], [ %prod.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %prod.j = phi i32 [ %prod.i, %for.i.header ], [ %prod.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load i32, ptr %idx, align 4
+  %prod.j.next = mul nsw i32 %prod.j, %a
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %prod.i.lcssa = phi i32 [ %prod.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_wrap_mul
+define void @reduction_wrap_mul(ptr %A) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %prod.i = phi i32 [ 1, %entry ], [ %prod.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %prod.j = phi i32 [ %prod.i, %for.i.header ], [ %prod.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load i32, ptr %idx, align 4
+  %prod.j.next = mul i32 %prod.j, %a
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %prod.i.lcssa = phi i32 [ %prod.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+
+; int b_or = 0;
+; for (int i = 0; i < 2; i++)
+;   for (int j = 0; j < 2; j++)
+;     b_or |= A[j][i];
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_or
+define void @reduction_or(ptr %A) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %or.i = phi i32 [ 0, %entry ], [ %or.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %or.j = phi i32 [ %or.i, %for.i.header ], [ %or.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load i32, ptr %idx, align 4
+  %or.j.next = or i32 %or.j, %a
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %or.i.lcssa = phi i32 [ %or.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+
+; int b_and = -1;
+; for (int i = 0; i < 2; i++)
+;   for (int j = 0; j < 2; j++)
+;     b_and &= A[j][i];
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_and
+define void @reduction_and(ptr %A) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %and.i = phi i32 [ -1, %entry ], [ %and.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %and.j = phi i32 [ %and.i, %for.i.header ], [ %and.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load i32, ptr %idx, align 4
+  %and.j.next = and i32 %and.j, %a
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %and.i.lcssa = phi i32 [ %and.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+
+; int b_xor = 0;
+; for (int i = 0; i < 2; i++)
+;   for (int j = 0; j < 2; j++)
+;     b_xor ^= A[j][i];
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_xor
+define void @reduction_xor(ptr %A) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %xor.i = phi i32 [ 0, %entry ], [ %xor.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %xor.j = phi i32 [ %xor.i, %for.i.header ], [ %xor.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load i32, ptr %idx, align 4
+  %xor.j.next = xor i32 %xor.j, %a
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %xor.i.lcssa = phi i32 [ %xor.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+
+; int smin = init;
+; for (int i = 0; i < 2; i++)
+;   for (int j = 0; j < 2; j++)
+;     smin = (A[j][i] < smin) ? A[j][i] : smin;
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_smin
+define void @reduction_smin(ptr %A, i32 %init) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %smin.i = phi i32 [ %init, %entry ], [ %smin.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %smin.j = phi i32 [ %smin.i, %for.i.header ], [ %smin.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load i32, ptr %idx, align 4
+  %cmp = icmp slt i32 %a, %smin.j
+  %smin.j.next = select i1 %cmp, i32 %a, i32 %smin.j
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %smin.i.lcssa = phi i32 [ %smin.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+
+; int smax = init;
+; for (int i = 0; i < 2; i++)
+;   for (int j = 0; j < 2; j++)
+;     smax = (A[j][i] > smax) ? A[j][i] : smax;
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_smax
+define void @reduction_smax(ptr %A, i32 %init) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %smax.i = phi i32 [ %init, %entry ], [ %smax.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %smax.j = phi i32 [ %smax.i, %for.i.header ], [ %smax.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load i32, ptr %idx, align 4
+  %cmp = icmp sgt i32 %a, %smax.j
+  %smax.j.next = select i1 %cmp, i32 %a, i32 %smax.j
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %smax.i.lcssa = phi i32 [ %smax.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+
+; unsigned umin = init;
+; for (int i = 0; i < 2; i++)
+;   for (int j = 0; j < 2; j++)
+;     umin = (A[j][i] < umin) ? A[j][i] : umin;
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_umin
+define void @reduction_umin(ptr %A, i32 %init) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %umin.i = phi i32 [ %init, %entry ], [ %umin.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %umin.j = phi i32 [ %umin.i, %for.i.header ], [ %umin.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load i32, ptr %idx, align 4
+  %cmp = icmp ult i32 %a, %umin.j
+  %umin.j.next = select i1 %cmp, i32 %a, i32 %umin.j
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %umin.i.lcssa = phi i32 [ %umin.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+
+; unsigned umax = 0;
+; for (int i = 0; i < 2; i++)
+;   for (int j = 0; j < 2; j++)
+;     smax = (A[j][i] > smax) ? A[j][i] : smax;
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_umax
+define void @reduction_umax(ptr %A) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %umax.i = phi i32 [ 0, %entry ], [ %umax.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %umax.j = phi i32 [ %umax.i, %for.i.header ], [ %umax.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load i32, ptr %idx, align 4
+  %cmp = icmp ugt i32 %a, %umax.j
+  %umax.j.next = select i1 %cmp, i32 %a, i32 %umax.j
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %umax.i.lcssa = phi i32 [ %umax.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+
+; int any_of = 0;
+; for (int i = 0; i < 2; i++)
+;   for (int j = 0; j < 2; j++)
+;     any_of = (A[j][i] == 42) ? 1 : any_of;
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_anyof
+define void @reduction_anyof(ptr %A) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %anyof.i = phi i32 [ 0, %entry ], [ %anyof.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %anyof.j = phi i32 [ %anyof.i, %for.i.header ], [ %anyof.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load i32, ptr %idx, align 4
+  %cmp = icmp eq i32 %a, 42
+  %anyof.j.next = select i1 %cmp, i32 1, i32 %anyof.j
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %anyof.i.lcssa = phi i32 [ %anyof.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+; float sum = 0;
+; for (int i = 0; i < 2; i++)
+;   for (int j = 0; j < 2; j++)
+;     sum += A[j][i];
+
+; CHECK:      --- !Missed
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            UnsupportedPHIOuter
+; CHECK-NEXT: Function:        reduction_fadd
+define void @reduction_fadd(ptr %A) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %sum.i = phi float [ 0.0, %entry ], [ %sum.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %sum.j = phi float [ %sum.i, %for.i.header ], [ %sum.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load float, ptr %idx, align 4
+  %sum.j.next = fadd float %sum.j, %a
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %sum.i.lcssa = phi float [ %sum.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_reassoc_fadd
+define void @reduction_reassoc_fadd(ptr %A) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %sum.i = phi float [ 0.0, %entry ], [ %sum.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %sum.j = phi float [ %sum.i, %for.i.header ], [ %sum.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load float, ptr %idx, align 4
+  %sum.j.next = fadd reassoc float %sum.j, %a
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %sum.i.lcssa = phi float [ %sum.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+; float prod = 1;
+; for (int i = 0; i < 2; i++)
+;   for (int j = 0; j < 2; j++)
+;     prod *= A[j][i];
+
+; CHECK:      --- !Missed
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            UnsupportedPHIOuter
+; CHECK-NEXT: Function:        reduction_fmul
+define void @reduction_fmul(ptr %A) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %prod.i = phi float [ 1.0, %entry ], [ %prod.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %prod.j = phi float [ %prod.i, %for.i.header ], [ %prod.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load float, ptr %idx, align 4
+  %prod.j.next = fmul float %prod.j, %a
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %prod.i.lcssa = phi float [ %prod.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_reassoc_fmul
+define void @reduction_reassoc_fmul(ptr %A) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %prod.i = phi float [ 1.0, %entry ], [ %prod.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %prod.j = phi float [ %prod.i, %for.i.header ], [ %prod.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load float, ptr %idx, align 4
+  %prod.j.next = fmul reassoc float %prod.j, %a
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %prod.i.lcssa = phi float [ %prod.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+; float fmuladd = 0;
+; for (int i = 0; i < 2; i++)
+;   for (int j = 0; j < 2; j++)
+;     fmuladd += A[j][i] * B[j][i];
+
+; CHECK:      --- !Missed
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            UnsupportedPHIOuter
+; CHECK-NEXT: Function:        reduction_fmuladd
+define void @reduction_fmuladd(ptr %A, ptr %B) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %fmuladd.i = phi float [ 1.0, %entry ], [ %fmuladd.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %fmuladd.j = phi float [ %fmuladd.i, %for.i.header ], [ %fmuladd.j.next, %for.j ]
+  %idx.a = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %idx.b = getelementptr inbounds [2 x [2 x i32]], ptr %B, i32 0, i32 %j, i32 %i
+  %a = load float, ptr %idx.a, align 4
+  %b = load float, ptr %idx.b, align 4
+  %fmuladd.j.next = call float @llvm.fmuladd.f32(float %a, float %b, float %fmuladd.j)
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %fmuladd.i.lcssa = phi float [ %fmuladd.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_reassoc_fmuladd
+define void @reduction_reassoc_fmuladd(ptr %A, ptr %B) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %fmuladd.i = phi float [ 1.0, %entry ], [ %fmuladd.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %fmuladd.j = phi float [ %fmuladd.i, %for.i.header ], [ %fmuladd.j.next, %for.j ]
+  %idx.a = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %idx.b = getelementptr inbounds [2 x [2 x i32]], ptr %B, i32 0, i32 %j, i32 %i
+  %a = load float, ptr %idx.a, align 4
+  %b = load float, ptr %idx.b, align 4
+  %fmuladd.j.next = call reassoc float @llvm.fmuladd.f32(float %a, float %b, float %fmuladd.j)
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %fmuladd.i.lcssa = phi float [ %fmuladd.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+; float fmin = init;
+; for (int i = 0; i < 2; i++)
+;   for (int j = 0; j < 2; j++)
+;     fmin = (A[j][i] < fmin) ? A[j][i] : fmin;
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_fmin
+define void @reduction_fmin(ptr %A, float %init) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %fmin.i = phi float [ %init, %entry ], [ %fmin.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %fmin.j = phi float [ %fmin.i, %for.i.header ], [ %fmin.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load float, ptr %idx, align 4
+  %cmp = fcmp nnan nsz olt float %a, %fmin.j
+  %fmin.j.next = select nnan nsz i1 %cmp, float %a, float %fmin.j
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %fmin.i.lcssa = phi float [ %fmin.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_fmininumnum
+define void @reduction_fmininumnum(ptr %A, float %init) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %fmin.i = phi float [ %init, %entry ], [ %fmin.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %fmin.j = phi float [ %fmin.i, %for.i.header ], [ %fmin.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load float, ptr %idx, align 4
+  %fmin.j.next = call float @llvm.minimumnum.f32(float %a, float %fmin.j)
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %fmin.i.lcssa = phi float [ %fmin.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+; float fmax = init;
+; for (int i = 0; i < 2; i++)
+;   for (int j = 0; j < 2; j++)
+;     fmax = (A[j][i] > fmax) ? A[j][i] : fmax;
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_fmax
+define void @reduction_fmax(ptr %A, float %init) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %fmax.i = phi float [ %init, %entry ], [ %fmax.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %fmax.j = phi float [ %fmax.i, %for.i.header ], [ %fmax.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load float, ptr %idx, align 4
+  %cmp = fcmp nnan nsz ogt float %a, %fmax.j
+  %fmax.j.next = select nnan nsz i1 %cmp, float %a, float %fmax.j
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %fmax.i.lcssa = phi float [ %fmax.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+; CHECK:      --- !Pass
+; CHECK-NEXT: Pass:            loop-interchange
+; CHECK-NEXT: Name:            Interchanged
+; CHECK-NEXT: Function:        reduction_fmaxinumnum
+define void @reduction_fmaxinumnum(ptr %A, float %init) {
+entry:
+  br label %for.i.header
+
+for.i.header:
+  %i = phi i32 [ 0, %entry ], [ %i.inc, %for.i.latch ]
+  %fmax.i = phi float [ %init, %entry ], [ %fmax.i.lcssa, %for.i.latch ]
+  br label %for.j
+
+for.j:
+  %j = phi i32 [ 0, %for.i.header ], [ %j.inc, %for.j ]
+  %fmax.j = phi float [ %fmax.i, %for.i.header ], [ %fmax.j.next, %for.j ]
+  %idx = getelementptr inbounds [2 x [2 x i32]], ptr %A, i32 0, i32 %j, i32 %i
+  %a = load float, ptr %idx, align 4
+  %fmax.j.next = call float @llvm.maximumnum.f32(float %a, float %fmax.j)
+  %j.inc = add i32 %j, 1
+  %cmp.j = icmp slt i32 %j.inc, 2
+  br i1 %cmp.j, label %for.j, label %for.i.latch
+
+for.i.latch:
+  %fmax.i.lcssa = phi float [ %fmax.j.next, %for.j ]
+  %i.inc = add i32 %i, 1
+  %cmp.i = icmp slt i32 %i.inc, 2
+  br i1 %cmp.i, label %for.i.header, label %exit
+
+exit:
+  ret void
+}
+
+declare float @llvm.fmuladd.f32(float %a, float %b, float %c)
+declare float @llvm.minimumnum.f32(float %a, float %b)
+declare float @llvm.maximumnum.f32(float %a, float %b)



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