1; RUN: opt < %s -S -indvars -loop-unroll -verify-loop-info | FileCheck %s 2; 3; Unit tests for loop unrolling using ScalarEvolution to compute trip counts. 4; 5; Indvars is run first to generate an "old" SCEV result. Some unit 6; tests may check that SCEV is properly invalidated between passes. 7 8; Completely unroll loops without a canonical IV. 9; 10; CHECK-LABEL: @sansCanonical( 11; CHECK-NOT: phi 12; CHECK-NOT: icmp 13; CHECK: ret 14define i32 @sansCanonical(i32* %base) nounwind { 15entry: 16 br label %while.body 17 18while.body: 19 %iv = phi i64 [ 10, %entry ], [ %iv.next, %while.body ] 20 %sum = phi i32 [ 0, %entry ], [ %sum.next, %while.body ] 21 %iv.next = add i64 %iv, -1 22 %adr = getelementptr inbounds i32* %base, i64 %iv.next 23 %tmp = load i32* %adr, align 8 24 %sum.next = add i32 %sum, %tmp 25 %iv.narrow = trunc i64 %iv.next to i32 26 %cmp.i65 = icmp sgt i32 %iv.narrow, 0 27 br i1 %cmp.i65, label %while.body, label %exit 28 29exit: 30 ret i32 %sum 31} 32 33; SCEV unrolling properly handles loops with multiple exits. In this 34; case, the computed trip count based on a canonical IV is *not* for a 35; latch block. Canonical unrolling incorrectly unrolls it, but SCEV 36; unrolling does not. 37; 38; CHECK-LABEL: @earlyLoopTest( 39; CHECK: tail: 40; CHECK-NOT: br 41; CHECK: br i1 %cmp2, label %loop, label %exit2 42define i64 @earlyLoopTest(i64* %base) nounwind { 43entry: 44 br label %loop 45 46loop: 47 %iv = phi i64 [ 0, %entry ], [ %inc, %tail ] 48 %s = phi i64 [ 0, %entry ], [ %s.next, %tail ] 49 %adr = getelementptr i64* %base, i64 %iv 50 %val = load i64* %adr 51 %s.next = add i64 %s, %val 52 %inc = add i64 %iv, 1 53 %cmp = icmp ne i64 %inc, 4 54 br i1 %cmp, label %tail, label %exit1 55 56tail: 57 %cmp2 = icmp ne i64 %val, 0 58 br i1 %cmp2, label %loop, label %exit2 59 60exit1: 61 ret i64 %s 62 63exit2: 64 ret i64 %s.next 65} 66 67; SCEV properly unrolls multi-exit loops. 68; 69; SCEV cannot currently unroll this loop. 70; It should ideally detect a trip count of 5. 71; rdar:14038809 [SCEV]: Optimize trip count computation for multi-exit loops. 72; CHECK-LABEL: @multiExit( 73; CHECKFIXME: getelementptr i32* %base, i32 10 74; CHECKFIXME-NEXT: load i32* 75; CHECKFIXME: br i1 false, label %l2.10, label %exit1 76; CHECKFIXME: l2.10: 77; CHECKFIXME-NOT: br 78; CHECKFIXME: ret i32 79define i32 @multiExit(i32* %base) nounwind { 80entry: 81 br label %l1 82l1: 83 %iv1 = phi i32 [ 0, %entry ], [ %inc1, %l2 ] 84 %iv2 = phi i32 [ 0, %entry ], [ %inc2, %l2 ] 85 %inc1 = add i32 %iv1, 1 86 %inc2 = add i32 %iv2, 1 87 %adr = getelementptr i32* %base, i32 %iv1 88 %val = load i32* %adr 89 %cmp1 = icmp slt i32 %iv1, 5 90 br i1 %cmp1, label %l2, label %exit1 91l2: 92 %cmp2 = icmp slt i32 %iv2, 10 93 br i1 %cmp2, label %l1, label %exit2 94exit1: 95 ret i32 1 96exit2: 97 ret i32 %val 98} 99 100 101; SCEV should not unroll a multi-exit loops unless the latch block has 102; a known trip count, regardless of the early exit trip counts. The 103; LoopUnroll utility uses this assumption to optimize the latch 104; block's branch. 105; 106; CHECK-LABEL: @multiExitIncomplete( 107; CHECK: l3: 108; CHECK-NOT: br 109; CHECK: br i1 %cmp3, label %l1, label %exit3 110define i32 @multiExitIncomplete(i32* %base) nounwind { 111entry: 112 br label %l1 113l1: 114 %iv1 = phi i32 [ 0, %entry ], [ %inc1, %l3 ] 115 %iv2 = phi i32 [ 0, %entry ], [ %inc2, %l3 ] 116 %inc1 = add i32 %iv1, 1 117 %inc2 = add i32 %iv2, 1 118 %adr = getelementptr i32* %base, i32 %iv1 119 %val = load i32* %adr 120 %cmp1 = icmp slt i32 %iv1, 5 121 br i1 %cmp1, label %l2, label %exit1 122l2: 123 %cmp2 = icmp slt i32 %iv2, 10 124 br i1 %cmp2, label %l3, label %exit2 125l3: 126 %cmp3 = icmp ne i32 %val, 0 127 br i1 %cmp3, label %l1, label %exit3 128 129exit1: 130 ret i32 1 131exit2: 132 ret i32 2 133exit3: 134 ret i32 3 135} 136 137; When loop unroll merges a loop exit with one of its parent loop's 138; exits, SCEV must forget its ExitNotTaken info. 139; 140; CHECK-LABEL: @nestedUnroll( 141; CHECK-NOT: br i1 142; CHECK: for.body87: 143define void @nestedUnroll() nounwind { 144entry: 145 br label %for.inc 146 147for.inc: 148 br i1 false, label %for.inc, label %for.body38.preheader 149 150for.body38.preheader: 151 br label %for.body38 152 153for.body38: 154 %i.113 = phi i32 [ %inc76, %for.inc74 ], [ 0, %for.body38.preheader ] 155 %mul48 = mul nsw i32 %i.113, 6 156 br label %for.body43 157 158for.body43: 159 %j.011 = phi i32 [ 0, %for.body38 ], [ %inc72, %for.body43 ] 160 %add49 = add nsw i32 %j.011, %mul48 161 %sh_prom50 = zext i32 %add49 to i64 162 %inc72 = add nsw i32 %j.011, 1 163 br i1 false, label %for.body43, label %for.inc74 164 165for.inc74: 166 %inc76 = add nsw i32 %i.113, 1 167 br i1 false, label %for.body38, label %for.body87.preheader 168 169for.body87.preheader: 170 br label %for.body87 171 172for.body87: 173 br label %for.body87 174} 175 176; PR16130: clang produces incorrect code with loop/expression at -O2 177; rdar:14036816 loop-unroll makes assumptions about undefined behavior 178; 179; The loop latch is assumed to exit after the first iteration because 180; of the induction variable's NSW flag. However, the loop latch's 181; equality test is skipped and the loop exits after the second 182; iteration via the early exit. So loop unrolling cannot assume that 183; the loop latch's exit count of zero is an upper bound on the number 184; of iterations. 185; 186; CHECK-LABEL: @nsw_latch( 187; CHECK: for.body: 188; CHECK: %b.03 = phi i32 [ 0, %entry ], [ %add, %for.cond ] 189; CHECK: return: 190; CHECK: %b.03.lcssa = phi i32 [ %b.03, %for.body ], [ %b.03, %for.cond ] 191define void @nsw_latch(i32* %a) nounwind { 192entry: 193 br label %for.body 194 195for.body: ; preds = %for.cond, %entry 196 %b.03 = phi i32 [ 0, %entry ], [ %add, %for.cond ] 197 %tobool = icmp eq i32 %b.03, 0 198 %add = add nsw i32 %b.03, 8 199 br i1 %tobool, label %for.cond, label %return 200 201for.cond: ; preds = %for.body 202 %cmp = icmp eq i32 %add, 13 203 br i1 %cmp, label %return, label %for.body 204 205return: ; preds = %for.body, %for.cond 206 %b.03.lcssa = phi i32 [ %b.03, %for.body ], [ %b.03, %for.cond ] 207 %retval.0 = phi i32 [ 1, %for.body ], [ 0, %for.cond ] 208 store i32 %b.03.lcssa, i32* %a, align 4 209 ret void 210} 211