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[Test] Add test on missing opportunity in Loop Deletion
We can break the backedge in some cases when we can evaluate some of the values and conditions on the 1st iteration.
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‎llvm/test/Transforms/LoopDeletion/eval_first_iteration.ll

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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -loop-deletion -S | FileCheck %s
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; RUN: opt < %s -passes='loop(loop-deletion)' -S | FileCheck %s
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; The idea is that we know that %is.positive is true on the 1st iteration,
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; it means that we can evaluate %merge.phi = %sub on the 1st iteration,
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; and therefore prove that %sum.next = %sum + %sub = %sum + %limit - %sum = %limit,
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; and predicate is false.
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; TODO: We can break the backedge here.
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define i32 @test_ne(i32 %limit) {
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; CHECK-LABEL: @test_ne(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[LOOP:%.*]]
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; CHECK: loop:
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; CHECK-NEXT: [[SUM:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[SUM_NEXT:%.*]], [[BACKEDGE:%.*]] ]
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; CHECK-NEXT: [[SUB:%.*]] = sub i32 [[LIMIT:%.*]], [[SUM]]
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; CHECK-NEXT: [[IS_POSITIVE:%.*]] = icmp sgt i32 [[SUB]], 0
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; CHECK-NEXT: br i1 [[IS_POSITIVE]], label [[BACKEDGE]], label [[IF_FALSE:%.*]]
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; CHECK: if.false:
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; CHECK-NEXT: br label [[BACKEDGE]]
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; CHECK: backedge:
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; CHECK-NEXT: [[MERGE_PHI:%.*]] = phi i32 [ 0, [[IF_FALSE]] ], [ [[SUB]], [[LOOP]] ]
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; CHECK-NEXT: [[SUM_NEXT]] = add i32 [[SUM]], [[MERGE_PHI]]
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; CHECK-NEXT: [[LOOP_COND:%.*]] = icmp ne i32 [[SUM_NEXT]], [[LIMIT]]
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; CHECK-NEXT: br i1 [[LOOP_COND]], label [[LOOP]], label [[DONE:%.*]]
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; CHECK: done:
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; CHECK-NEXT: [[SUM_NEXT_LCSSA:%.*]] = phi i32 [ [[SUM_NEXT]], [[BACKEDGE]] ]
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; CHECK-NEXT: ret i32 [[SUM_NEXT_LCSSA]]
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;
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entry:
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br label %loop
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loop: ; preds = %backedge, %entry
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%sum = phi i32 [ 0, %entry ], [ %sum.next, %backedge ]
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%sub = sub i32 %limit, %sum
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%is.positive = icmp sgt i32 %sub, 0
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br i1 %is.positive, label %backedge, label %if.false
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if.false: ; preds = %loop
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br label %backedge
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backedge: ; preds = %if.false, %loop
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%merge.phi = phi i32 [ 0, %if.false ], [ %sub, %loop ]
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%sum.next = add i32 %sum, %merge.phi
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%loop.cond = icmp ne i32 %sum.next, %limit
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br i1 %loop.cond, label %loop, label %done
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done: ; preds = %backedge
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%sum.next.lcssa = phi i32 [ %sum.next, %backedge ]
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ret i32 %sum.next.lcssa
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}
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; TODO: We can break the backedge here.
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define i32 @test_slt(i32 %limit) {
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; CHECK-LABEL: @test_slt(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[LOOP:%.*]]
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; CHECK: loop:
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; CHECK-NEXT: [[SUM:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[SUM_NEXT:%.*]], [[BACKEDGE:%.*]] ]
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; CHECK-NEXT: [[SUB:%.*]] = sub i32 [[LIMIT:%.*]], [[SUM]]
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; CHECK-NEXT: [[IS_POSITIVE:%.*]] = icmp sgt i32 [[SUB]], 0
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; CHECK-NEXT: br i1 [[IS_POSITIVE]], label [[BACKEDGE]], label [[IF_FALSE:%.*]]
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; CHECK: if.false:
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; CHECK-NEXT: br label [[BACKEDGE]]
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; CHECK: backedge:
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; CHECK-NEXT: [[MERGE_PHI:%.*]] = phi i32 [ 0, [[IF_FALSE]] ], [ [[SUB]], [[LOOP]] ]
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; CHECK-NEXT: [[SUM_NEXT]] = add i32 [[SUM]], [[MERGE_PHI]]
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; CHECK-NEXT: [[LOOP_COND:%.*]] = icmp slt i32 [[SUM_NEXT]], [[LIMIT]]
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; CHECK-NEXT: br i1 [[LOOP_COND]], label [[LOOP]], label [[DONE:%.*]]
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; CHECK: done:
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; CHECK-NEXT: [[SUM_NEXT_LCSSA:%.*]] = phi i32 [ [[SUM_NEXT]], [[BACKEDGE]] ]
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; CHECK-NEXT: ret i32 [[SUM_NEXT_LCSSA]]
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;
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entry:
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br label %loop
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loop: ; preds = %backedge, %entry
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%sum = phi i32 [ 0, %entry ], [ %sum.next, %backedge ]
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%sub = sub i32 %limit, %sum
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%is.positive = icmp sgt i32 %sub, 0
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br i1 %is.positive, label %backedge, label %if.false
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if.false: ; preds = %loop
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br label %backedge
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backedge: ; preds = %if.false, %loop
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%merge.phi = phi i32 [ 0, %if.false ], [ %sub, %loop ]
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%sum.next = add i32 %sum, %merge.phi
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%loop.cond = icmp slt i32 %sum.next, %limit
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br i1 %loop.cond, label %loop, label %done
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done: ; preds = %backedge
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%sum.next.lcssa = phi i32 [ %sum.next, %backedge ]
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ret i32 %sum.next.lcssa
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}
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; TODO: We can break the backedge here.
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define i32 @test_ult(i32 %limit) {
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; CHECK-LABEL: @test_ult(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[LOOP:%.*]]
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; CHECK: loop:
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; CHECK-NEXT: [[SUM:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[SUM_NEXT:%.*]], [[BACKEDGE:%.*]] ]
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; CHECK-NEXT: [[SUB:%.*]] = sub i32 [[LIMIT:%.*]], [[SUM]]
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; CHECK-NEXT: [[IS_POSITIVE:%.*]] = icmp sgt i32 [[SUB]], 0
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; CHECK-NEXT: br i1 [[IS_POSITIVE]], label [[BACKEDGE]], label [[IF_FALSE:%.*]]
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; CHECK: if.false:
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; CHECK-NEXT: br label [[BACKEDGE]]
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; CHECK: backedge:
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; CHECK-NEXT: [[MERGE_PHI:%.*]] = phi i32 [ 0, [[IF_FALSE]] ], [ [[SUB]], [[LOOP]] ]
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; CHECK-NEXT: [[SUM_NEXT]] = add i32 [[SUM]], [[MERGE_PHI]]
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; CHECK-NEXT: [[LOOP_COND:%.*]] = icmp ult i32 [[SUM_NEXT]], [[LIMIT]]
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; CHECK-NEXT: br i1 [[LOOP_COND]], label [[LOOP]], label [[DONE:%.*]]
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; CHECK: done:
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; CHECK-NEXT: [[SUM_NEXT_LCSSA:%.*]] = phi i32 [ [[SUM_NEXT]], [[BACKEDGE]] ]
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; CHECK-NEXT: ret i32 [[SUM_NEXT_LCSSA]]
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;
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entry:
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br label %loop
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loop: ; preds = %backedge, %entry
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%sum = phi i32 [ 0, %entry ], [ %sum.next, %backedge ]
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%sub = sub i32 %limit, %sum
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%is.positive = icmp sgt i32 %sub, 0
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br i1 %is.positive, label %backedge, label %if.false
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if.false: ; preds = %loop
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br label %backedge
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backedge: ; preds = %if.false, %loop
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%merge.phi = phi i32 [ 0, %if.false ], [ %sub, %loop ]
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%sum.next = add i32 %sum, %merge.phi
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%loop.cond = icmp ult i32 %sum.next, %limit
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br i1 %loop.cond, label %loop, label %done
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done: ; preds = %backedge
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%sum.next.lcssa = phi i32 [ %sum.next, %backedge ]
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ret i32 %sum.next.lcssa
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}
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; TODO: We can break the backedge here.
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define i32 @test_sgt(i32 %limit) {
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; CHECK-LABEL: @test_sgt(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[LOOP:%.*]]
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; CHECK: loop:
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; CHECK-NEXT: [[SUM:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[SUM_NEXT:%.*]], [[BACKEDGE:%.*]] ]
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; CHECK-NEXT: [[SUB:%.*]] = sub i32 [[LIMIT:%.*]], [[SUM]]
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; CHECK-NEXT: [[IS_POSITIVE:%.*]] = icmp sgt i32 [[SUB]], 0
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; CHECK-NEXT: br i1 [[IS_POSITIVE]], label [[BACKEDGE]], label [[IF_FALSE:%.*]]
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; CHECK: if.false:
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; CHECK-NEXT: br label [[BACKEDGE]]
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; CHECK: backedge:
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; CHECK-NEXT: [[MERGE_PHI:%.*]] = phi i32 [ 0, [[IF_FALSE]] ], [ [[SUB]], [[LOOP]] ]
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; CHECK-NEXT: [[SUM_NEXT]] = add i32 [[SUM]], [[MERGE_PHI]]
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; CHECK-NEXT: [[LOOP_COND:%.*]] = icmp sgt i32 [[SUM_NEXT]], [[LIMIT]]
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; CHECK-NEXT: br i1 [[LOOP_COND]], label [[LOOP]], label [[DONE:%.*]]
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; CHECK: done:
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; CHECK-NEXT: [[SUM_NEXT_LCSSA:%.*]] = phi i32 [ [[SUM_NEXT]], [[BACKEDGE]] ]
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; CHECK-NEXT: ret i32 [[SUM_NEXT_LCSSA]]
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;
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entry:
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br label %loop
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loop: ; preds = %backedge, %entry
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%sum = phi i32 [ 0, %entry ], [ %sum.next, %backedge ]
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%sub = sub i32 %limit, %sum
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%is.positive = icmp sgt i32 %sub, 0
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br i1 %is.positive, label %backedge, label %if.false
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if.false: ; preds = %loop
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br label %backedge
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backedge: ; preds = %if.false, %loop
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%merge.phi = phi i32 [ 0, %if.false ], [ %sub, %loop ]
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%sum.next = add i32 %sum, %merge.phi
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%loop.cond = icmp sgt i32 %sum.next, %limit
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br i1 %loop.cond, label %loop, label %done
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done: ; preds = %backedge
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%sum.next.lcssa = phi i32 [ %sum.next, %backedge ]
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ret i32 %sum.next.lcssa
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}
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; TODO: We can break the backedge here.
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define i32 @test_ugt(i32 %limit) {
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; CHECK-LABEL: @test_ugt(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[LOOP:%.*]]
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; CHECK: loop:
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; CHECK-NEXT: [[SUM:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[SUM_NEXT:%.*]], [[BACKEDGE:%.*]] ]
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; CHECK-NEXT: [[SUB:%.*]] = sub i32 [[LIMIT:%.*]], [[SUM]]
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; CHECK-NEXT: [[IS_POSITIVE:%.*]] = icmp sgt i32 [[SUB]], 0
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; CHECK-NEXT: br i1 [[IS_POSITIVE]], label [[BACKEDGE]], label [[IF_FALSE:%.*]]
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; CHECK: if.false:
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; CHECK-NEXT: br label [[BACKEDGE]]
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; CHECK: backedge:
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; CHECK-NEXT: [[MERGE_PHI:%.*]] = phi i32 [ 0, [[IF_FALSE]] ], [ [[SUB]], [[LOOP]] ]
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; CHECK-NEXT: [[SUM_NEXT]] = add i32 [[SUM]], [[MERGE_PHI]]
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; CHECK-NEXT: [[LOOP_COND:%.*]] = icmp ugt i32 [[SUM_NEXT]], [[LIMIT]]
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; CHECK-NEXT: br i1 [[LOOP_COND]], label [[LOOP]], label [[DONE:%.*]]
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; CHECK: done:
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; CHECK-NEXT: [[SUM_NEXT_LCSSA:%.*]] = phi i32 [ [[SUM_NEXT]], [[BACKEDGE]] ]
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; CHECK-NEXT: ret i32 [[SUM_NEXT_LCSSA]]
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;
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entry:
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br label %loop
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loop: ; preds = %backedge, %entry
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%sum = phi i32 [ 0, %entry ], [ %sum.next, %backedge ]
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%sub = sub i32 %limit, %sum
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%is.positive = icmp sgt i32 %sub, 0
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br i1 %is.positive, label %backedge, label %if.false
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if.false: ; preds = %loop
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br label %backedge
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backedge: ; preds = %if.false, %loop
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%merge.phi = phi i32 [ 0, %if.false ], [ %sub, %loop ]
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%sum.next = add i32 %sum, %merge.phi
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%loop.cond = icmp ugt i32 %sum.next, %limit
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br i1 %loop.cond, label %loop, label %done
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done: ; preds = %backedge
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%sum.next.lcssa = phi i32 [ %sum.next, %backedge ]
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ret i32 %sum.next.lcssa
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}

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