; RUN: opt < %s -loop-unswitch -enable-new-pm=0 -verify-loop-info -S < %s 2>&1 | FileCheck %s ; RUN: opt < %s -loop-unswitch -enable-new-pm=0 -verify-loop-info -enable-mssa-loop-dependency=true -verify-memoryssa -S < %s 2>&1 | FileCheck %s @sink = global i32 0, align 4 @y = global i64 0, align 8 ; The following is approximately: ; void f(bool x, int p, int q) { ; volatile bool x2 = x; ; for (int i = 0; i < 1; ++i) { ; if (x2) { ; if (y) ; sink = p; ; else ; sink = q; ; } ; } ; } ; With MemorySanitizer, the loop can not be unswitched on "y", because "y" could ; be uninitialized when x == false. ; Test that the branch on "y" is inside the loop (after the first unconditional ; branch). define void @may_not_execute(i1 zeroext %x, i32 %p, i32 %q) sanitize_memory { ; CHECK-LABEL: @may_not_execute( entry: ; CHECK: %[[Y:.*]] = load i64, i64* @y, align 8 ; CHECK: %[[YB:.*]] = icmp eq i64 %[[Y]], 0 ; CHECK-NOT: br i1 ; CHECK: br label ; CHECK: br i1 %[[YB]] %x2 = alloca i8, align 1 %frombool1 = zext i1 %x to i8 store volatile i8 %frombool1, i8* %x2, align 1 %0 = load i64, i64* @y, align 8 %tobool3 = icmp eq i64 %0, 0 br label %for.body for.body: %i.01 = phi i32 [ 0, %entry ], [ %inc, %for.inc ] %x2.0. = load volatile i8, i8* %x2, align 1 %tobool2 = icmp eq i8 %x2.0., 0 br i1 %tobool2, label %for.inc, label %if.then if.then: br i1 %tobool3, label %if.else, label %if.then4 if.then4: store volatile i32 %p, i32* @sink, align 4 br label %for.inc if.else: store volatile i32 %q, i32* @sink, align 4 br label %for.inc for.inc: %inc = add nsw i32 %i.01, 1 %cmp = icmp slt i32 %inc, 1 br i1 %cmp, label %for.body, label %for.end for.end: ret void } ; The same as above, but "y" is a function parameter instead of a global. ; This shows that it is not enough to suppress hoisting of load instructions, ; the actual problem is in the speculative branching. define void @may_not_execute2(i1 zeroext %x, i1 zeroext %y, i32 %p, i32 %q) sanitize_memory { ; CHECK-LABEL: @may_not_execute2( entry: ; CHECK-NOT: br i1 ; CHECK: br label ; CHECK: br i1 %y, %x2 = alloca i8, align 1 %frombool2 = zext i1 %x to i8 store volatile i8 %frombool2, i8* %x2, align 1 br label %for.body for.body: %i.01 = phi i32 [ 0, %entry ], [ %inc, %for.inc ] %x2.0. = load volatile i8, i8* %x2, align 1 %tobool3 = icmp eq i8 %x2.0., 0 br i1 %tobool3, label %for.inc, label %if.then if.then: br i1 %y, label %if.then5, label %if.else if.then5: store volatile i32 %p, i32* @sink, align 4 br label %for.inc if.else: store volatile i32 %q, i32* @sink, align 4 br label %for.inc for.inc: %inc = add nsw i32 %i.01, 1 %cmp = icmp slt i32 %inc, 1 br i1 %cmp, label %for.body, label %for.end for.end: ret void } ; The following is approximately: ; void f(bool x, int p, int q) { ; volatile bool x2 = x; ; for (int i = 0; i < 1; ++i) { ; if (y) ; sink = p; ; else ; sink = q; ; } ; } ; "if (y)" is guaranteed to execute; the loop can be unswitched. define void @must_execute(i1 zeroext %x, i32 %p, i32 %q) sanitize_memory { ; CHECK-LABEL: @must_execute( entry: ; CHECK: %[[Y:.*]] = load i64, i64* @y, align 8 ; CHECK-NEXT: %[[YB:.*]] = icmp eq i64 %[[Y]], 0 ; CHECK-NEXT: br i1 %[[YB]], %x2 = alloca i8, align 1 %frombool1 = zext i1 %x to i8 store volatile i8 %frombool1, i8* %x2, align 1 %0 = load i64, i64* @y, align 8 %tobool2 = icmp eq i64 %0, 0 br label %for.body for.body: %i.01 = phi i32 [ 0, %entry ], [ %inc, %for.inc ] br i1 %tobool2, label %if.else, label %if.then if.then: store volatile i32 %p, i32* @sink, align 4 br label %for.inc if.else: store volatile i32 %q, i32* @sink, align 4 br label %for.inc for.inc: %inc = add nsw i32 %i.01, 1 %cmp = icmp slt i32 %inc, 1 br i1 %cmp, label %for.body, label %for.end for.end: ret void }