1 ; RUN: opt < %s -S -indvars -loop-unroll -verify-loop-info | FileCheck %s
3 ; Unit tests for loop unrolling using ScalarEvolution to compute trip counts.
5 ; Indvars is run first to generate an "old" SCEV result. Some unit
6 ; tests may check that SCEV is properly invalidated between passes.
8 ; Completely unroll loops without a canonical IV.
10 ; CHECK-LABEL: @sansCanonical(
14 define i32 @sansCanonical(i32* %base) nounwind {
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, i32* %base, i64 %iv.next
23 %tmp = load i32, 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
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
38 ; CHECK-LABEL: @earlyLoopTest(
41 ; CHECK: br i1 %cmp2, label %loop, label %exit2
42 define i64 @earlyLoopTest(i64* %base) nounwind {
47 %iv = phi i64 [ 0, %entry ], [ %inc, %tail ]
48 %s = phi i64 [ 0, %entry ], [ %s.next, %tail ]
49 %adr = getelementptr i64, i64* %base, i64 %iv
50 %val = load i64, i64* %adr
51 %s.next = add i64 %s, %val
53 %cmp = icmp ne i64 %inc, 4
54 br i1 %cmp, label %tail, label %exit1
57 %cmp2 = icmp ne i64 %val, 0
58 br i1 %cmp2, label %loop, label %exit2
67 ; SCEV properly unrolls multi-exit loops.
69 ; CHECK-LABEL: @multiExit(
70 ; CHECK: getelementptr i32, i32* %base, i32 10
71 ; CHECK-NEXT: load i32, i32*
72 ; CHECK: br i1 false, label %l2.10, label %exit1
76 define i32 @multiExit(i32* %base) nounwind {
80 %iv1 = phi i32 [ 0, %entry ], [ %inc1, %l2 ]
81 %iv2 = phi i32 [ 0, %entry ], [ %inc2, %l2 ]
82 %inc1 = add i32 %iv1, 1
83 %inc2 = add i32 %iv2, 1
84 %adr = getelementptr i32, i32* %base, i32 %iv1
85 %val = load i32, i32* %adr
86 %cmp1 = icmp slt i32 %iv1, 5
87 br i1 %cmp1, label %l2, label %exit1
89 %cmp2 = icmp slt i32 %iv2, 10
90 br i1 %cmp2, label %l1, label %exit2
98 ; SCEV should not unroll a multi-exit loops unless the latch block has
99 ; a known trip count, regardless of the early exit trip counts. The
100 ; LoopUnroll utility uses this assumption to optimize the latch
103 ; CHECK-LABEL: @multiExitIncomplete(
106 ; CHECK: br i1 %cmp3, label %l1, label %exit3
107 define i32 @multiExitIncomplete(i32* %base) nounwind {
111 %iv1 = phi i32 [ 0, %entry ], [ %inc1, %l3 ]
112 %iv2 = phi i32 [ 0, %entry ], [ %inc2, %l3 ]
113 %inc1 = add i32 %iv1, 1
114 %inc2 = add i32 %iv2, 1
115 %adr = getelementptr i32, i32* %base, i32 %iv1
116 %val = load i32, i32* %adr
117 %cmp1 = icmp slt i32 %iv1, 5
118 br i1 %cmp1, label %l2, label %exit1
120 %cmp2 = icmp slt i32 %iv2, 10
121 br i1 %cmp2, label %l3, label %exit2
123 %cmp3 = icmp ne i32 %val, 0
124 br i1 %cmp3, label %l1, label %exit3
134 ; When loop unroll merges a loop exit with one of its parent loop's
135 ; exits, SCEV must forget its ExitNotTaken info.
137 ; CHECK-LABEL: @nestedUnroll(
140 define void @nestedUnroll() nounwind {
145 br i1 false, label %for.inc, label %for.body38.preheader
147 for.body38.preheader:
151 %i.113 = phi i32 [ %inc76, %for.inc74 ], [ 0, %for.body38.preheader ]
152 %mul48 = mul nsw i32 %i.113, 6
156 %j.011 = phi i32 [ 0, %for.body38 ], [ %inc72, %for.body43 ]
157 %add49 = add nsw i32 %j.011, %mul48
158 %sh_prom50 = zext i32 %add49 to i64
159 %inc72 = add nsw i32 %j.011, 1
160 br i1 false, label %for.body43, label %for.inc74
163 %inc76 = add nsw i32 %i.113, 1
164 br i1 false, label %for.body38, label %for.body87.preheader
166 for.body87.preheader:
173 ; PR16130: clang produces incorrect code with loop/expression at -O2
174 ; rdar:14036816 loop-unroll makes assumptions about undefined behavior
176 ; The loop latch is assumed to exit after the first iteration because
177 ; of the induction variable's NSW flag. However, the loop latch's
178 ; equality test is skipped and the loop exits after the second
179 ; iteration via the early exit. So loop unrolling cannot assume that
180 ; the loop latch's exit count of zero is an upper bound on the number
183 ; CHECK-LABEL: @nsw_latch(
185 ; CHECK: %b.03 = phi i32 [ 0, %entry ], [ %add, %for.cond ]
187 ; CHECK: %b.03.lcssa = phi i32 [ 8, %for.body ], [ 0, %for.cond ]
188 define void @nsw_latch(i32* %a) nounwind {
192 for.body: ; preds = %for.cond, %entry
193 %b.03 = phi i32 [ 0, %entry ], [ %add, %for.cond ]
194 %tobool = icmp eq i32 %b.03, 0
195 %add = add nsw i32 %b.03, 8
196 br i1 %tobool, label %for.cond, label %return
198 for.cond: ; preds = %for.body
199 %cmp = icmp eq i32 %add, 13
200 br i1 %cmp, label %return, label %for.body
202 return: ; preds = %for.body, %for.cond
203 %b.03.lcssa = phi i32 [ %b.03, %for.body ], [ %b.03, %for.cond ]
204 %retval.0 = phi i32 [ 1, %for.body ], [ 0, %for.cond ]
205 store i32 %b.03.lcssa, i32* %a, align 4