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[Test] Add some tests showing room for optimization exploiting undef and UB
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‎llvm/test/Transforms/LoopDeletion/eval_first_iteration.ll

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Original file line numberDiff line numberDiff line change
@@ -731,6 +731,228 @@ failure:
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unreachable
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}
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; TODO: We can break the backedge here by assuming that undef = sub.
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define i32 @test_multiple_pred_undef_1() {
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; CHECK-LABEL: @test_multiple_pred_undef_1(
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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 4, [[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 [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
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; CHECK: if.true:
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; CHECK-NEXT: br i1 undef, label [[IF_TRUE_1:%.*]], label [[IF_TRUE_2:%.*]]
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; CHECK: if.true.1:
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; CHECK-NEXT: br label [[BACKEDGE]]
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; CHECK: if.true.2:
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; CHECK-NEXT: br label [[BACKEDGE]]
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; CHECK: if.false:
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; CHECK-NEXT: br i1 undef, label [[IF_FALSE_1:%.*]], label [[IF_FALSE_2:%.*]]
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; CHECK: if.false.1:
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; CHECK-NEXT: br label [[BACKEDGE]]
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; CHECK: if.false.2:
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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_1]] ], [ 0, [[IF_FALSE_2]] ], [ [[SUB]], [[IF_TRUE_1]] ], [ undef, [[IF_TRUE_2]] ]
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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]], 4
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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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; CHECK: failure:
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; CHECK-NEXT: unreachable
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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 4, %sum
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%is.positive = icmp sgt i32 %sub, 0
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br i1 %is.positive, label %if.true, label %if.false
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if.true:
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br i1 undef, label %if.true.1, label %if.true.2
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if.true.1:
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br label %backedge
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if.true.2:
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br label %backedge
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if.false: ; preds = %loop
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br i1 undef, label %if.false.1, label %if.false.2
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if.false.1:
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br label %backedge
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if.false.2:
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br label %backedge
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backedge:
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%merge.phi = phi i32 [ 0, %if.false.1 ], [ 0, %if.false.2 ], [ %sub, %if.true.1 ], [ undef, %if.true.2 ]
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%sum.next = add i32 %sum, %merge.phi
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%loop.cond = icmp ne i32 %sum.next, 4
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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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failure:
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unreachable
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}
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; TODO: We can break the backedge here by assuming that undef = sub.
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define i32 @test_multiple_pred_undef_2() {
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; CHECK-LABEL: @test_multiple_pred_undef_2(
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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 4, [[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 [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
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; CHECK: if.true:
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; CHECK-NEXT: br i1 undef, label [[IF_TRUE_1:%.*]], label [[IF_TRUE_2:%.*]]
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; CHECK: if.true.1:
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; CHECK-NEXT: br label [[BACKEDGE]]
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; CHECK: if.true.2:
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; CHECK-NEXT: br label [[BACKEDGE]]
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; CHECK: if.false:
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; CHECK-NEXT: br i1 undef, label [[IF_FALSE_1:%.*]], label [[IF_FALSE_2:%.*]]
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; CHECK: if.false.1:
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; CHECK-NEXT: br label [[BACKEDGE]]
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; CHECK: if.false.2:
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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_1]] ], [ 0, [[IF_FALSE_2]] ], [ undef, [[IF_TRUE_1]] ], [ [[SUB]], [[IF_TRUE_2]] ]
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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]], 4
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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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; CHECK: failure:
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; CHECK-NEXT: unreachable
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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 4, %sum
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%is.positive = icmp sgt i32 %sub, 0
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br i1 %is.positive, label %if.true, label %if.false
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if.true:
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br i1 undef, label %if.true.1, label %if.true.2
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if.true.1:
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br label %backedge
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if.true.2:
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br label %backedge
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if.false: ; preds = %loop
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br i1 undef, label %if.false.1, label %if.false.2
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if.false.1:
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br label %backedge
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if.false.2:
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br label %backedge
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backedge:
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%merge.phi = phi i32 [ 0, %if.false.1 ], [ 0, %if.false.2 ], [ undef, %if.true.1 ], [ %sub, %if.true.2 ]
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%sum.next = add i32 %sum, %merge.phi
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%loop.cond = icmp ne i32 %sum.next, 4
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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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failure:
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unreachable
880+
}
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; TODO: We can break the backedge here by exploiting undef.
883+
define i32 @test_multiple_pred_undef_3() {
884+
; CHECK-LABEL: @test_multiple_pred_undef_3(
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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 4, [[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 [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
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; CHECK: if.true:
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; CHECK-NEXT: br i1 undef, label [[IF_TRUE_1:%.*]], label [[IF_TRUE_2:%.*]]
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; CHECK: if.true.1:
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; CHECK-NEXT: br label [[BACKEDGE]]
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; CHECK: if.true.2:
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; CHECK-NEXT: br label [[BACKEDGE]]
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; CHECK: if.false:
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; CHECK-NEXT: br i1 undef, label [[IF_FALSE_1:%.*]], label [[IF_FALSE_2:%.*]]
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; CHECK: if.false.1:
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; CHECK-NEXT: br label [[BACKEDGE]]
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; CHECK: if.false.2:
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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_1]] ], [ 0, [[IF_FALSE_2]] ], [ undef, [[IF_TRUE_1]] ], [ undef, [[IF_TRUE_2]] ]
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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]], 4
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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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; CHECK: failure:
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; CHECK-NEXT: unreachable
914+
;
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entry:
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br label %loop
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loop: ; preds = %backedge, %entry
919+
%sum = phi i32 [ 0, %entry ], [ %sum.next, %backedge ]
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%sub = sub i32 4, %sum
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%is.positive = icmp sgt i32 %sub, 0
922+
br i1 %is.positive, label %if.true, label %if.false
923+
924+
if.true:
925+
br i1 undef, label %if.true.1, label %if.true.2
926+
927+
if.true.1:
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br label %backedge
929+
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if.true.2:
931+
br label %backedge
932+
933+
if.false: ; preds = %loop
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br i1 undef, label %if.false.1, label %if.false.2
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936+
if.false.1:
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br label %backedge
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if.false.2:
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br label %backedge
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942+
backedge:
943+
%merge.phi = phi i32 [ 0, %if.false.1 ], [ 0, %if.false.2 ], [ undef, %if.true.1 ], [ undef, %if.true.2 ]
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%sum.next = add i32 %sum, %merge.phi
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%loop.cond = icmp ne i32 %sum.next, 4
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br i1 %loop.cond, label %loop, label %done
947+
948+
done: ; preds = %backedge
949+
%sum.next.lcssa = phi i32 [ %sum.next, %backedge ]
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ret i32 %sum.next.lcssa
951+
952+
failure:
953+
unreachable
954+
}
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734956
; TODO: We can break the backedge here.
735957
define i32 @test_select(i32 %limit) {
736958
; CHECK-LABEL: @test_select(

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