de2fed6152
The unrolling code was previously inserting new cloned blocks at the end of the function. The result of this with typical loop structures is that the new iterations are placed far from the initial iteration. With unrolling, the general assumption is that the a) the loop is reasonable hot, and b) the first Count-1 copies of the loop are rarely (if ever) loop exiting. As such, placing Count-1 copies out of line is a fairly poor code placement choice. We'd much rather fall through into the hot (non-exiting) path. For code with branch profiles, later layout would fix this, but this may have a positive impact on non-PGO compiled code. However, the real motivation for this change isn't performance. Its readability and human understanding. Having to jump around long distances in an IR file to trace an unrolled loop structure is error prone and tedious.
161 lines
7.9 KiB
LLVM
161 lines
7.9 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -loop-unroll -simplifycfg -instcombine -simplifycfg -S -mtriple arm-none-eabi -mcpu=cortex-m7 %s | FileCheck %s
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; This test is meant to check that this loop is unrolled into three iterations.
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define void @test(i32* %x, i32 %n) {
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; CHECK-LABEL: @test(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[SUB:%.*]] = add nsw i32 [[N:%.*]], -1
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; CHECK-NEXT: [[REM:%.*]] = srem i32 [[SUB]], 4
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; CHECK-NEXT: [[CMP7:%.*]] = icmp sgt i32 [[REM]], 0
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; CHECK-NEXT: br i1 [[CMP7]], label [[WHILE_BODY:%.*]], label [[WHILE_END:%.*]]
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; CHECK: while.body:
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; CHECK-NEXT: [[TMP0:%.*]] = load i32, i32* [[X:%.*]], align 4
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; CHECK-NEXT: [[CMP1:%.*]] = icmp slt i32 [[TMP0]], 10
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; CHECK-NEXT: br i1 [[CMP1]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
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; CHECK: if.then:
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; CHECK-NEXT: store i32 0, i32* [[X]], align 4
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; CHECK-NEXT: br label [[IF_END]]
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; CHECK: if.end:
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; CHECK-NEXT: [[INCDEC_PTR:%.*]] = getelementptr inbounds i32, i32* [[X]], i64 1
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; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[REM]], 1
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; CHECK-NEXT: br i1 [[CMP]], label [[WHILE_BODY_1:%.*]], label [[WHILE_END]]
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; CHECK: while.body.1:
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; CHECK-NEXT: [[TMP1:%.*]] = load i32, i32* [[INCDEC_PTR]], align 4
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; CHECK-NEXT: [[CMP1_1:%.*]] = icmp slt i32 [[TMP1]], 10
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; CHECK-NEXT: br i1 [[CMP1_1]], label [[IF_THEN_1:%.*]], label [[IF_END_1:%.*]]
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; CHECK: if.then.1:
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; CHECK-NEXT: store i32 0, i32* [[INCDEC_PTR]], align 4
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; CHECK-NEXT: br label [[IF_END_1]]
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; CHECK: if.end.1:
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; CHECK-NEXT: [[INCDEC_PTR_1:%.*]] = getelementptr inbounds i32, i32* [[X]], i64 2
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; CHECK-NEXT: [[CMP_1:%.*]] = icmp sgt i32 [[REM]], 2
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; CHECK-NEXT: br i1 [[CMP_1]], label [[WHILE_BODY_2:%.*]], label [[WHILE_END]]
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; CHECK: while.body.2:
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; CHECK-NEXT: [[TMP2:%.*]] = load i32, i32* [[INCDEC_PTR_1]], align 4
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; CHECK-NEXT: [[CMP1_2:%.*]] = icmp slt i32 [[TMP2]], 10
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; CHECK-NEXT: br i1 [[CMP1_2]], label [[IF_THEN_2:%.*]], label [[WHILE_END]]
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; CHECK: if.then.2:
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; CHECK-NEXT: store i32 0, i32* [[INCDEC_PTR_1]], align 4
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; CHECK-NEXT: br label [[WHILE_END]]
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; CHECK: while.end:
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; CHECK-NEXT: ret void
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;
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entry:
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%sub = add nsw i32 %n, -1
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%rem = srem i32 %sub, 4
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%cmp7 = icmp sgt i32 %rem, 0
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br i1 %cmp7, label %while.body, label %while.end
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while.body: ; preds = %entry, %if.end
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%x.addr.09 = phi i32* [ %incdec.ptr, %if.end ], [ %x, %entry ]
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%n.addr.08 = phi i32 [ %dec, %if.end ], [ %rem, %entry ]
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%0 = load i32, i32* %x.addr.09, align 4
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%cmp1 = icmp slt i32 %0, 10
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br i1 %cmp1, label %if.then, label %if.end
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if.then: ; preds = %while.body
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store i32 0, i32* %x.addr.09, align 4
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br label %if.end
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if.end: ; preds = %if.then, %while.body
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%incdec.ptr = getelementptr inbounds i32, i32* %x.addr.09, i32 1
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%dec = add nsw i32 %n.addr.08, -1
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%cmp = icmp sgt i32 %dec, 0
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br i1 %cmp, label %while.body, label %while.end
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while.end: ; preds = %if.end, %entry
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ret void
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}
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; Larger test that is still fully unrolled, thanks in part to the constant data and the max upper bound.
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@data = internal constant [50 x i32] [i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15, i32 16, i32 17, i32 18, i32 19, i32 20, i32 21, i32 22, i32 23, i32 24, i32 25, i32 26, i32 27, i32 28, i32 29, i32 30, i32 31, i32 32, i32 33, i32 34, i32 35, i32 36, i32 37, i32 38, i32 39, i32 40, i32 41, i32 42, i32 43, i32 44, i32 45, i32 46, i32 47, i32 48, i32 49, i32 50], align 4
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define i32 @test2(i32 %l86) {
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; CHECK-LABEL: @test2(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[L86_OFF:%.*]] = add i32 [[L86:%.*]], -1
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; CHECK-NEXT: [[SWITCH:%.*]] = icmp ult i32 [[L86_OFF]], 24
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; CHECK-NEXT: [[DOTNOT30:%.*]] = icmp ne i32 [[L86]], 25
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; CHECK-NEXT: [[SPEC_SELECT:%.*]] = zext i1 [[DOTNOT30]] to i32
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; CHECK-NEXT: [[COMMON_RET_OP:%.*]] = select i1 [[SWITCH]], i32 0, i32 [[SPEC_SELECT]]
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; CHECK-NEXT: ret i32 [[COMMON_RET_OP]]
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;
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entry:
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br label %for.body.i.i
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for.body.i.i: ; preds = %for.body.i.i.preheader, %for.inc.i.3.i
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%i.0137.i.i = phi i32 [ %add.i.3.i, %for.inc.i.3.i ], [ 0, %entry ]
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%add.i.i = or i32 %i.0137.i.i, 1
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%arrayidx.i.i = getelementptr inbounds i32, i32* getelementptr inbounds ([50 x i32], [50 x i32]* @data, i32 0, i32 0), i32 %add.i.i
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%l93 = load i32, i32* %arrayidx.i.i, align 4
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%cmp1.i.i = icmp sgt i32 %l93, %l86
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br i1 %cmp1.i.i, label %land.lhs.true.i.i, label %for.inc.i.i
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land.lhs.true.i.i: ; preds = %for.body.i.i
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%arrayidx2.i.i = getelementptr inbounds i32, i32* getelementptr inbounds ([50 x i32], [50 x i32]* @data, i32 0, i32 0), i32 %i.0137.i.i
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%l94 = load i32, i32* %arrayidx2.i.i, align 4
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%cmp3.not.i.i = icmp sgt i32 %l94, %l86
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br i1 %cmp3.not.i.i, label %for.inc.i.i, label %for.end.i.if.end8.i_crit_edge.i.loopexit
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for.inc.i.i: ; preds = %land.lhs.true.i.i, %for.body.i.i
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%exitcond.not.i.i = icmp eq i32 %add.i.i, 25
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br i1 %exitcond.not.i.i, label %if.then6.i.i.loopexitsplit, label %for.body.i.1.i
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for.body.i.1.i: ; preds = %for.inc.i.i
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%add.i.1.i = or i32 %i.0137.i.i, 2
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%arrayidx.i.1.i = getelementptr inbounds i32, i32* getelementptr inbounds ([50 x i32], [50 x i32]* @data, i32 0, i32 0), i32 %add.i.1.i
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%l345 = load i32, i32* %arrayidx.i.1.i, align 4
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%cmp1.i.1.i = icmp sgt i32 %l345, %l86
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br i1 %cmp1.i.1.i, label %land.lhs.true.i.1.i, label %for.inc.i.1.i
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land.lhs.true.i.1.i: ; preds = %for.body.i.1.i
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br i1 %cmp1.i.i, label %for.inc.i.1.i, label %for.end.i.i
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for.inc.i.1.i: ; preds = %land.lhs.true.i.1.i, %for.body.i.1.i
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%add.i.2.i = or i32 %i.0137.i.i, 3
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%arrayidx.i.2.i = getelementptr inbounds i32, i32* getelementptr inbounds ([50 x i32], [50 x i32]* @data, i32 0, i32 0), i32 %add.i.2.i
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%l346 = load i32, i32* %arrayidx.i.2.i, align 4
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%cmp1.i.2.i = icmp sgt i32 %l346, %l86
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br i1 %cmp1.i.2.i, label %land.lhs.true.i.2.i, label %for.inc.i.2.i
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land.lhs.true.i.2.i: ; preds = %for.inc.i.1.i
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br i1 %cmp1.i.1.i, label %for.inc.i.2.i, label %for.end.i.if.end8.i_crit_edge.i.loopexit
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for.inc.i.2.i: ; preds = %land.lhs.true.i.2.i, %for.inc.i.1.i
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br label %for.body.i.3.i
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for.body.i.3.i: ; preds = %for.inc.i.2.i
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%add.i.3.i = add nuw nsw i32 %i.0137.i.i, 4
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%arrayidx.i.3.i = getelementptr inbounds i32, i32* getelementptr inbounds ([50 x i32], [50 x i32]* @data, i32 0, i32 0), i32 %add.i.3.i
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%l347 = load i32, i32* %arrayidx.i.3.i, align 4
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%cmp1.i.3.i = icmp sgt i32 %l347, %l86
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br i1 %cmp1.i.3.i, label %land.lhs.true.i.3.i, label %for.inc.i.3.i
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land.lhs.true.i.3.i: ; preds = %for.body.i.3.i
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br i1 %cmp1.i.2.i, label %for.inc.i.3.i, label %for.end.i.i
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for.inc.i.3.i: ; preds = %land.lhs.true.i.3.i, %for.body.i.3.i
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br label %for.body.i.i
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for.end.i.if.end8.i_crit_edge.i.loopexit: ; preds = %land.lhs.true.i.i, %land.lhs.true.i.2.i
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%i.0.lcssa.i.i3.ph = phi i32 [ %i.0137.i.i, %land.lhs.true.i.i ], [ %add.i.1.i, %land.lhs.true.i.2.i ]
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br label %for.end.i.if.end8.i_crit_edge.i
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if.then6.i.i.loopexitsplit: ; preds = %for.inc.i.i
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br label %if.then6.i.i.loopexit
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for.end.i.i: ; preds = %land.lhs.true.i.3.i, %land.lhs.true.i.1.i
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%i.0.lcssa.i.i = phi i32 [ %add.i.i, %land.lhs.true.i.1.i ], [ %add.i.2.i, %land.lhs.true.i.3.i ]
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%cmp5.i.i = icmp eq i32 %i.0.lcssa.i.i, 25
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br i1 %cmp5.i.i, label %if.then6.i.i, label %for.end.i.if.end8.i_crit_edge.i
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for.end.i.if.end8.i_crit_edge.i:
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ret i32 0
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if.then6.i.i.loopexit:
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ret i32 1
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if.then6.i.i:
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ret i32 2
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}
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