[llvm] [LoopInterchange] Reject interchange if non-reassociative reduction exists (PR #148612)
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Mon Jul 14 04:38:52 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: Ryotaro Kasuga (kasuga-fj)
<details>
<summary>Changes</summary>
---
Patch is 29.52 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/148612.diff
3 Files Affected:
- (modified) llvm/lib/Transforms/Scalar/LoopInterchange.cpp (+56-1)
- (modified) llvm/test/Transforms/LoopInterchange/pr48212.ll (+1-1)
- (added) llvm/test/Transforms/LoopInterchange/reductions-kind.ll (+864)
``````````diff
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...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/148612
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