Add a missing test.

This is a test for r272421: Disable MSan-hostile loop unswitching.

llvm-svn: 272713

llvm/test/Transforms/LoopUnswitch/msan.ll

@@ -0,0 +1,153 @@
+; RUN: opt < %s -loop-unswitch -verify-loop-info -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
+}