1 ; RUN: opt < %s -loop-unswitch -verify-loop-info -S < %s 2>&1 | FileCheck %s 2 3 @sink = global i32 0, align 4 4 @y = global i64 0, align 8 5 6 ; The following is approximately: 7 ; void f(bool x, int p, int q) { 8 ; volatile bool x2 = x; 9 ; for (int i = 0; i < 1; ++i) { 10 ; if (x2) { 11 ; if (y) 12 ; sink = p; 13 ; else 14 ; sink = q; 15 ; } 16 ; } 17 ; } 18 ; With MemorySanitizer, the loop can not be unswitched on "y", because "y" could 19 ; be uninitialized when x == false. 20 ; Test that the branch on "y" is inside the loop (after the first unconditional 21 ; branch). 22 23 define void @may_not_execute(i1 zeroext %x, i32 %p, i32 %q) sanitize_memory { 24 ; CHECK-LABEL: @may_not_execute( 25 entry: 26 ; CHECK: %[[Y:.*]] = load i64, i64* @y, align 8 27 ; CHECK: %[[YB:.*]] = icmp eq i64 %[[Y]], 0 28 ; CHECK-NOT: br i1 29 ; CHECK: br label 30 ; CHECK: br i1 %[[YB]] 31 32 %x2 = alloca i8, align 1 33 %frombool1 = zext i1 %x to i8 34 store volatile i8 %frombool1, i8* %x2, align 1 35 %0 = load i64, i64* @y, align 8 36 %tobool3 = icmp eq i64 %0, 0 37 br label %for.body 38 39 for.body: 40 %i.01 = phi i32 [ 0, %entry ], [ %inc, %for.inc ] 41 %x2.0. = load volatile i8, i8* %x2, align 1 42 %tobool2 = icmp eq i8 %x2.0., 0 43 br i1 %tobool2, label %for.inc, label %if.then 44 45 if.then: 46 br i1 %tobool3, label %if.else, label %if.then4 47 48 if.then4: 49 store volatile i32 %p, i32* @sink, align 4 50 br label %for.inc 51 52 if.else: 53 store volatile i32 %q, i32* @sink, align 4 54 br label %for.inc 55 56 for.inc: 57 %inc = add nsw i32 %i.01, 1 58 %cmp = icmp slt i32 %inc, 1 59 br i1 %cmp, label %for.body, label %for.end 60 61 for.end: 62 ret void 63 } 64 65 66 ; The same as above, but "y" is a function parameter instead of a global. 67 ; This shows that it is not enough to suppress hoisting of load instructions, 68 ; the actual problem is in the speculative branching. 69 70 define void @may_not_execute2(i1 zeroext %x, i1 zeroext %y, i32 %p, i32 %q) sanitize_memory { 71 ; CHECK-LABEL: @may_not_execute2( 72 entry: 73 ; CHECK-NOT: br i1 74 ; CHECK: br label 75 ; CHECK: br i1 %y, 76 %x2 = alloca i8, align 1 77 %frombool2 = zext i1 %x to i8 78 store volatile i8 %frombool2, i8* %x2, align 1 79 br label %for.body 80 81 for.body: 82 %i.01 = phi i32 [ 0, %entry ], [ %inc, %for.inc ] 83 %x2.0. = load volatile i8, i8* %x2, align 1 84 %tobool3 = icmp eq i8 %x2.0., 0 85 br i1 %tobool3, label %for.inc, label %if.then 86 87 if.then: 88 br i1 %y, label %if.then5, label %if.else 89 90 if.then5: 91 store volatile i32 %p, i32* @sink, align 4 92 br label %for.inc 93 94 if.else: 95 store volatile i32 %q, i32* @sink, align 4 96 br label %for.inc 97 98 for.inc: 99 %inc = add nsw i32 %i.01, 1 100 %cmp = icmp slt i32 %inc, 1 101 br i1 %cmp, label %for.body, label %for.end 102 103 for.end: 104 ret void 105 } 106 107 108 ; The following is approximately: 109 ; void f(bool x, int p, int q) { 110 ; volatile bool x2 = x; 111 ; for (int i = 0; i < 1; ++i) { 112 ; if (y) 113 ; sink = p; 114 ; else 115 ; sink = q; 116 ; } 117 ; } 118 ; "if (y)" is guaranteed to execute; the loop can be unswitched. 119 120 define void @must_execute(i1 zeroext %x, i32 %p, i32 %q) sanitize_memory { 121 ; CHECK-LABEL: @must_execute( 122 entry: 123 ; CHECK: %[[Y:.*]] = load i64, i64* @y, align 8 124 ; CHECK-NEXT: %[[YB:.*]] = icmp eq i64 %[[Y]], 0 125 ; CHECK-NEXT: br i1 %[[YB]], 126 127 %x2 = alloca i8, align 1 128 %frombool1 = zext i1 %x to i8 129 store volatile i8 %frombool1, i8* %x2, align 1 130 %0 = load i64, i64* @y, align 8 131 %tobool2 = icmp eq i64 %0, 0 132 br label %for.body 133 134 for.body: 135 %i.01 = phi i32 [ 0, %entry ], [ %inc, %for.inc ] 136 br i1 %tobool2, label %if.else, label %if.then 137 138 if.then: 139 store volatile i32 %p, i32* @sink, align 4 140 br label %for.inc 141 142 if.else: 143 store volatile i32 %q, i32* @sink, align 4 144 br label %for.inc 145 146 for.inc: 147 %inc = add nsw i32 %i.01, 1 148 %cmp = icmp slt i32 %inc, 1 149 br i1 %cmp, label %for.body, label %for.end 150 151 for.end: 152 ret void 153 } 154
