1 ; RUN: opt -passes='loop(unswitch),verify<loops>' -S < %s | FileCheck %s 2 3 declare void @unknown() 4 declare void @unknown2() 5 6 @y = global i64 0, align 8 7 8 ; The following is approximately: 9 ; void f(bool *x) { 10 ; for (int i = 0; i < 1; ++i) { 11 ; if (*x) { 12 ; if (y) 13 ; unknown(); 14 ; else 15 ; break; 16 ; } 17 ; } 18 ; } 19 ; With MemorySanitizer, the loop can not be unswitched on "y", because "y" could 20 ; be uninitialized when x == false. 21 ; Test that the branch on "y" is inside the loop (after the first unconditional 22 ; branch). 23 24 define void @may_not_execute_trivial(i1* %x) sanitize_memory { 25 ; CHECK-LABEL: @may_not_execute_trivial( 26 entry: 27 %y = load i64, i64* @y, align 8 28 %y.cmp = icmp eq i64 %y, 0 29 br label %for.body 30 ; CHECK: %[[Y:.*]] = load i64, i64* @y 31 ; CHECK: %[[YCMP:.*]] = icmp eq i64 %[[Y]], 0 32 ; CHECK-NOT: br i1 33 ; CHECK: br label %for.body 34 35 for.body: 36 %i = phi i32 [ 0, %entry ], [ %inc, %for.inc ] 37 %x.load = load i1, i1* %x 38 br i1 %x.load, label %for.inc, label %if.then 39 ; CHECK: %[[XLOAD:.*]] = load i1, i1* %x 40 ; CHECK: br i1 %[[XLOAD]] 41 42 if.then: 43 br i1 %y.cmp, label %for.end, label %if.then4 44 ; CHECK: br i1 %[[YCMP]] 45 46 if.then4: 47 call void @unknown() 48 br label %for.inc 49 50 for.inc: 51 %inc = add nsw i32 %i, 1 52 %cmp = icmp slt i32 %inc, 1 53 br i1 %cmp, label %for.body, label %for.end 54 55 for.end: 56 ret void 57 } 58 59 60 ; The same as above, but "y" is a function parameter instead of a global. 61 ; This shows that it is not enough to suppress hoisting of load instructions, 62 ; the actual problem is in the speculative branching. 63 64 define void @may_not_execute2_trivial(i1* %x, i1 %y) sanitize_memory { 65 ; CHECK-LABEL: @may_not_execute2_trivial( 66 entry: 67 br label %for.body 68 ; CHECK-NOT: br i1 69 ; CHECK: br label %for.body 70 71 for.body: 72 %i = phi i32 [ 0, %entry ], [ %inc, %for.inc ] 73 %x.load = load i1, i1* %x 74 br i1 %x.load, label %for.inc, label %if.then 75 ; CHECK: %[[XLOAD:.*]] = load i1, i1* %x 76 ; CHECK: br i1 %[[XLOAD]] 77 78 if.then: 79 br i1 %y, label %for.end, label %if.then4 80 ; CHECK: br i1 %y 81 82 if.then4: 83 call void @unknown() 84 br label %for.inc 85 86 for.inc: 87 %inc = add nsw i32 %i, 1 88 %cmp = icmp slt i32 %inc, 1 89 br i1 %cmp, label %for.body, label %for.end 90 91 for.end: 92 ret void 93 } 94 95 96 ; The following is approximately: 97 ; void f() { 98 ; for (int i = 0; i < 1; ++i) { 99 ; if (y) 100 ; unknown(); 101 ; else 102 ; break; 103 ; } 104 ; } 105 ; "if (y)" is guaranteed to execute; the loop can be unswitched. 106 107 define void @must_execute_trivial() sanitize_memory { 108 ; CHECK-LABEL: @must_execute_trivial( 109 entry: 110 %y = load i64, i64* @y, align 8 111 %y.cmp = icmp eq i64 %y, 0 112 br label %for.body 113 ; CHECK: %[[Y:.*]] = load i64, i64* @y 114 ; CHECK: %[[YCMP:.*]] = icmp eq i64 %[[Y]], 0 115 ; CHECK: br i1 %[[YCMP]], label %[[EXIT_SPLIT:.*]], label %[[PH:.*]] 116 ; 117 ; CHECK: [[PH]]: 118 ; CHECK: br label %for.body 119 120 for.body: 121 %i = phi i32 [ 0, %entry ], [ %inc, %for.inc ] 122 br i1 %y.cmp, label %for.end, label %if.then4 123 ; CHECK: br label %if.then4 124 125 if.then4: 126 call void @unknown() 127 br label %for.inc 128 129 for.inc: 130 %inc = add nsw i32 %i, 1 131 %cmp = icmp slt i32 %inc, 1 132 br i1 %cmp, label %for.body, label %for.end 133 134 for.end: 135 ret void 136 ; CHECK: for.end: 137 ; CHECK: br label %[[EXIT_SPLIT]] 138 ; 139 ; CHECK: [[EXIT_SPLIT]]: 140 ; CHECK: ret void 141 } 142
