1; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-threshold=10 -unroll-percent-dynamic-cost-saved-threshold=70 -unroll-dynamic-cost-savings-discount=90 | FileCheck %s 2target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" 3 4@unknown_global = internal unnamed_addr global [9 x i32] [i32 0, i32 -1, i32 0, i32 -1, i32 5, i32 -1, i32 0, i32 -1, i32 0], align 16 5@weak_constant = weak unnamed_addr constant [9 x i32] [i32 0, i32 -1, i32 0, i32 -1, i32 5, i32 -1, i32 0, i32 -1, i32 0], align 16 6 7; Though @unknown_global is initialized with constant values, we can't consider 8; it as a constant, so we shouldn't unroll the loop. 9; CHECK-LABEL: @foo 10; CHECK: %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @unknown_global, i64 0, i64 %iv 11define i32 @foo(i32* noalias nocapture readonly %src) { 12entry: 13 br label %loop 14 15loop: ; preds = %loop, %entry 16 %iv = phi i64 [ 0, %entry ], [ %inc, %loop ] 17 %r = phi i32 [ 0, %entry ], [ %add, %loop ] 18 %arrayidx = getelementptr inbounds i32, i32* %src, i64 %iv 19 %src_element = load i32, i32* %arrayidx, align 4 20 %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @unknown_global, i64 0, i64 %iv 21 %const_array_element = load i32, i32* %array_const_idx, align 4 22 %mul = mul nsw i32 %src_element, %const_array_element 23 %add = add nsw i32 %mul, %r 24 %inc = add nuw nsw i64 %iv, 1 25 %exitcond86.i = icmp eq i64 %inc, 9 26 br i1 %exitcond86.i, label %loop.end, label %loop 27 28loop.end: ; preds = %loop 29 %r.lcssa = phi i32 [ %r, %loop ] 30 ret i32 %r.lcssa 31} 32 33; Similarly, we can't consider 'weak' symbols as a known constant value, so we 34; shouldn't unroll the loop. 35; CHECK-LABEL: @foo2 36; CHECK: %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @weak_constant, i64 0, i64 %iv 37define i32 @foo2(i32* noalias nocapture readonly %src) { 38entry: 39 br label %loop 40 41loop: ; preds = %loop, %entry 42 %iv = phi i64 [ 0, %entry ], [ %inc, %loop ] 43 %r = phi i32 [ 0, %entry ], [ %add, %loop ] 44 %arrayidx = getelementptr inbounds i32, i32* %src, i64 %iv 45 %src_element = load i32, i32* %arrayidx, align 4 46 %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @weak_constant, i64 0, i64 %iv 47 %const_array_element = load i32, i32* %array_const_idx, align 4 48 %mul = mul nsw i32 %src_element, %const_array_element 49 %add = add nsw i32 %mul, %r 50 %inc = add nuw nsw i64 %iv, 1 51 %exitcond86.i = icmp eq i64 %inc, 9 52 br i1 %exitcond86.i, label %loop.end, label %loop 53 54loop.end: ; preds = %loop 55 %r.lcssa = phi i32 [ %r, %loop ] 56 ret i32 %r.lcssa 57} 58 59; In this case the loaded value is used only to control branch. 60; If we missed that, we could've thought that it's unused and unrolling would 61; clean up almost entire loop. Make sure that we do not unroll such loop. 62; CHECK-LABEL: @foo3 63; CHECK: br i1 %exitcond, label %loop.end, label %loop.header 64define i32 @foo3(i32* noalias nocapture readonly %src) { 65entry: 66 br label %loop.header 67 68loop.header: 69 %iv = phi i64 [ 0, %entry ], [ %inc, %loop.latch ] 70 %r1 = phi i32 [ 0, %entry ], [ %r3, %loop.latch ] 71 %arrayidx = getelementptr inbounds i32, i32* %src, i64 %iv 72 %src_element = load i32, i32* %arrayidx, align 4 73 %cmp = icmp eq i32 0, %src_element 74 br i1 %cmp, label %loop.if, label %loop.latch 75 76loop.if: 77 %r2 = add i32 %r1, 1 78 br label %loop.latch 79 80loop.latch: 81 %r3 = phi i32 [%r1, %loop.header], [%r2, %loop.if] 82 %inc = add nuw nsw i64 %iv, 1 83 %exitcond = icmp eq i64 %inc, 9 84 br i1 %exitcond, label %loop.end, label %loop.header 85 86loop.end: 87 %r.lcssa = phi i32 [ %r3, %loop.latch ] 88 ret i32 %r.lcssa 89} 90