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1; RUN: opt -passes='loop(simple-loop-unswitch),verify<loops>' -S < %s | FileCheck %s2; RUN: opt -verify-memoryssa -passes='loop-mssa(simple-loop-unswitch),verify<loops>' -S < %s | FileCheck %s3 4declare void @unknown()5declare void @unknown2()6 7@y = global i64 0, align 88 9; The following is approximately:10; void f(bool *x) {11; for (int i = 0; i < 1; ++i) {12; if (*x) {13; if (y)14; unknown();15; else16; break;17; }18; }19; }20; With MemorySanitizer, the loop can not be unswitched on "y", because "y" could21; be uninitialized when x == false.22; Test that the branch on "y" is inside the loop (after the first unconditional23; branch).24 25define void @may_not_execute_trivial(ptr %x) sanitize_memory {26; CHECK-LABEL: @may_not_execute_trivial(27entry:28 %y = load i64, ptr @y, align 829 %y.cmp = icmp eq i64 %y, 030 br label %for.body31; CHECK: %[[Y:.*]] = load i64, ptr @y32; CHECK: %[[YCMP:.*]] = icmp eq i64 %[[Y]], 033; CHECK-NOT: br i134; CHECK: br label %for.body35 36for.body:37 %i = phi i32 [ 0, %entry ], [ %inc, %for.inc ]38 %x.load = load i1, ptr %x39 br i1 %x.load, label %for.inc, label %if.then40; CHECK: %[[XLOAD:.*]] = load i1, ptr %x41; CHECK: br i1 %[[XLOAD]]42 43if.then:44 br i1 %y.cmp, label %for.end, label %if.then445; CHECK: br i1 %[[YCMP]]46 47if.then4:48 call void @unknown()49 br label %for.inc50 51for.inc:52 %inc = add nsw i32 %i, 153 %cmp = icmp slt i32 %inc, 154 br i1 %cmp, label %for.body, label %for.end55 56for.end:57 ret void58}59 60 61; The same as above, but "y" is a function parameter instead of a global.62; This shows that it is not enough to suppress hoisting of load instructions,63; the actual problem is in the speculative branching.64 65define void @may_not_execute2_trivial(ptr %x, i1 %y) sanitize_memory {66; CHECK-LABEL: @may_not_execute2_trivial(67entry:68 br label %for.body69; CHECK-NOT: br i170; CHECK: br label %for.body71 72for.body:73 %i = phi i32 [ 0, %entry ], [ %inc, %for.inc ]74 %x.load = load i1, ptr %x75 br i1 %x.load, label %for.inc, label %if.then76; CHECK: %[[XLOAD:.*]] = load i1, ptr %x77; CHECK: br i1 %[[XLOAD]]78 79if.then:80 br i1 %y, label %for.end, label %if.then481; CHECK: br i1 %y82 83if.then4:84 call void @unknown()85 br label %for.inc86 87for.inc:88 %inc = add nsw i32 %i, 189 %cmp = icmp slt i32 %inc, 190 br i1 %cmp, label %for.body, label %for.end91 92for.end:93 ret void94}95 96 97; The following is approximately:98; void f() {99; for (int i = 0; i < 1; ++i) {100; if (y)101; unknown();102; else103; break;104; }105; }106; "if (y)" is guaranteed to execute; the loop can be unswitched.107 108define void @must_execute_trivial() sanitize_memory {109; CHECK-LABEL: @must_execute_trivial(110entry:111 %y = load i64, ptr @y, align 8112 %y.cmp = icmp eq i64 %y, 0113 br label %for.body114; CHECK: %[[Y:.*]] = load i64, ptr @y115; CHECK: %[[YCMP:.*]] = icmp eq i64 %[[Y]], 0116; CHECK: br i1 %[[YCMP]], label %[[EXIT_SPLIT:.*]], label %[[PH:.*]]117;118; CHECK: [[PH]]:119; CHECK: br label %for.body120 121for.body:122 %i = phi i32 [ 0, %entry ], [ %inc, %for.inc ]123 br i1 %y.cmp, label %for.end, label %if.then4124; CHECK: br label %if.then4125 126if.then4:127 call void @unknown()128 br label %for.inc129 130for.inc:131 %inc = add nsw i32 %i, 1132 %cmp = icmp slt i32 %inc, 1133 br i1 %cmp, label %for.body, label %for.end134 135for.end:136 ret void137; CHECK: for.end:138; CHECK: br label %[[EXIT_SPLIT]]139;140; CHECK: [[EXIT_SPLIT]]:141; CHECK: ret void142}143